CHAPTER 1 - FLIGHT THEORY & AIRCRAFT

Standard Rate Turn – The aircraft moves through three degrees of turn per second. Therefore, a turn of 180o would take
one minute, and a complete 360o circle would take two minutes. This is also known as a “rate one” turn.
Attitude (Pitch) plus Power (Throttle) = Performance. This formula is very important!
Fuselage – Houses passengers, pilots, cargo. Does not include the engine cowling, which houses the aircraft’s engine.
The Attitude Indicator is sometimes called the Artificial Horizon.
The Altimeter must always be set to the proper barometric pressure in order to give accurate and useful readings.
However, in some areas such as all high level airspace, and in Northern Domestic Airspace (which are SPR’s or Standard
Pressure Regions), all altimeters are set to 29.92, the international standard.
The Heading Indicator is sometimes called the Directional Gyro.
The VHF Omnidirectional Range (VOR) is the primary system used to define airways.
Instrument Landing System (ILS) – A very sensitive VOR that also includes vertical and glide slope info. Useful for
precision approaches when landing in poor weather conditions.
Automatic Direction Finder (ADF) – Sometimes referred to as the Radio Compass. Mode C Transponders can send
back altitude info to ATC (not all transponders can).
Types of Airframes:
- Truss - Steel tubes covered with metal, fabric, or composite materials for aerodynamic purposes. The primary
tubes used are called longerons. Shorter cross-bracing tubes can be called struts and can be run horizontally,
vertically, or diagonally. Stringers can run along the top.
- Semi-Monocoque - A series of formers or bulkheads held together by stringers (360o orientation). The frame is
then wrapped with a stressed skin. This skin takes some of the load.
Monocoque – Similar to semi-monocoque but does not have stringers. Less rivets, less skin friction.
- Composite - – Make use of materials like fiberglass or kevlar. Stronger and lighter than metal and do not have
fatiguing problems.
- Bulkhead – A partition within an airframe used as a divider or barrier.
Advantages of Tricycle Gear:
- Does not nose over as easily. - Better visibility over the nose while taxiing.
- Better directional stability on the ground. - Better ground handling.
Advantages of Conventional Gear:
- More propeller clearance. - Better on rough and unimproved runways.
- Less parasite drag from landing gear. - Less damage to the plane if the wheel gives out.
Retractable Landing Gear:
- Huge reduction in parasite drag and noise.
- More complicated, and risky that you could be distracted and land with it retracted.
- Operated by electrics, hydraulics, or manually (always has a manual backup).
Types of Main Gear:
- Split Axle: Bungie or oleo.
- Spring Steel Cantilever: Steel or composite, flexes.
- Single Strut: Oleo (almost vertical).
Differential Braking – Brakes can be operated independently (more control, tighter turns).
Heels on floor! Never land with brakes on!!
Flaps:
- Increase the lift and drag of the wing by increasing the camber.
- Can be electric, hydraulic, or manual.
- Types include: Plain, split, slotted, fowler, or combinations thereof.
Tires that are either low pressure and/or large are better on soft or rough airstrips.
Flaperon – Combination aileron and flaps. The pilot has separate controls and mechanical devices to make it work.
Although slightly more complex, it can reduce the weight of an aircraft.
Cowling Flaps – Control the amount of air circulating around the engine for cooling. They are partially or fully closed
during cruise/descent or when less air is needed.
Horizontally Opposed Engine – This is the most common type of reciprocating, air-cooled, four-stroke piston engine
used in GA aircraft.
The ring gear is not what makes your propeller spin. It is only connected to the starter when cranking the engine. The
prop is spun because it is connected to the pistons via the camshaft.
Each cylinder in an aviation piston engine has two spark plugs for redundancy.
Radial Piston Engine:
- Round shaped, air cooled with an odd number - Economical to buy, but maintenance intensive.
of cylinders (per bank). - Guzzles oil, using a dry sump
- High power-to-weight ratio.
Most aviation (and automotive) engines are four-stroke, as opposed to something like a chainsaw or lawn mower, which
are only two-stroke.
Four Stroke Cycle:
1. Intake: The intake valve is open and the exhaust valve is closed, which creates a vacuum. Vacuum pulls the
fuel/air mixture into the cylinder through the open intake valve. At this point, the piston is only moving due to
inertia. The camshaft is what opens the intake valve.
2. Compression: Both valves are closed. Compression of the fuel & air allows the mixture to reach its maximum
potency.
3. Power: Both valves are still closed. Prior to the piston reaching the top dead center, the spark plug fires. As the
mixture burns (not explodes) it forces the piston back down.
4. Exhaust: The piston is coming back up. The exhaust valve is open to allow exhaust to leave the cylinder.
Most piston engines are air cooled, although a few are liquid cooled. But liquid cooling is heavier and more
complex, although there is less drag in liquid-cooled.
Magneto – Provides electrical current to the spark plugs (not supplied by the battery). Magnetos are always alive
and are designed to continue operating even after a magneto ground wire failure. Modern aviation piston engines
have two magnetos, cross-wired to each cylinder, as a redundant fail-safe.
A shroud is often placed around the muffler to provide cabin heat. However, leaks are possible, which can lead to
carbon monoxide poisoning. If you smell exhaust in the cabin, turn off the cabin heat.
Mixture Control:
- Rich means that it is heavy to fuel.
- The proper ratio of fuel to air is 1:14 or 1:15 by weight, not by volume.
- A lean mix increases engine efficiency and saves fuel. Also runs cleaner (avoids spark plug fouling and
pre-ignition).
The Throttle and Mixture can have varying settings, from all the way “in” to all the way “out,” like a light on a
dimmer switch. Although carb heat has a similar type of “plunger” control, you should only ever do “all the way in”
or “all the way out” for carb heat. Carb heat is either On or Off.
Be aware that when the carb heat is on, your aircraft is ingesting unfiltered air. Turbochargers and Superchargers
compress and increase the density of air. As we climb, the air becomes less dense, so compressing it makes the
engine perform the same way as if it was at a lower altitude.
Turbocharger:
- Powered by the engine exhaust turning the - Hot, expensive, maintenance intensive.
turbine. - Compresses air prior to entering the carb.
- Lightweight, does not rob power from the engine. - Engine is not turbocharged when the waste-gate
is open
Supercharger:
- Powered directly by the engine (gear driven off the crankshaft).
- Reliable, not expensive.
- Compresses fuel/air downstream of the carb.
Density altitude is the altitude that the aircraft thinks it is operating at.
A “chop and drop” where you have a large power reduction and descend quickly, is hard on the engine due to shock
cooling.
Engines with temperature gauges should generally not be allowed to cool more than 30oC per minute. Do a partial block
of the engine intake in sub-zero temperatures.
Optional Gauges that you might see on some aircraft include:
- Cylinder head temperature. - Carb temperature.
- Exhaust gas temperature (EGT). - Fuel flow/pressure.
Brake Horsepower – The power available after friction and other losses have been accounted for. A landing is nothing
more than a controlled crash. And if you’re worried about landing with the engines out, remember that glider pilots do it
every single time. The camshaft only rotates once for every two rotations of the crankshaft.
Know the difference between a piston and a turbine engine. The piston engine is also known as a reciprocating engine
because the mechanism (piston) moves back and forth. A turbine is based upon a rotary or circular design. A piston
engine can move a large amount of air fairly quickly. A turbine can move a smaller amount of air extremely quickly.
A turboprop is what results when you put a prop onto a turbine engine instead of onto a piston. It is a hybrid
design which gives some advantages to each type of engine. Turbochargers are not associated with turbine
engines, despite the similarity in the names.
The carburetor (carb) has two purposes. It mixes the fuel and air in the proper ratio, and it regulates the amount
of that fuel/air mix that enters the engine.
Updraft Float Carburetor:
- Mounted under the engine. - Has a small chamber with fuel and a float valve to
- Outside air routed through ducts in the carb. regulate fuel demands.
- Fuel/air mix sucked up into the engine. - As fuel leaves the carb, it is vaporized going into
the piston intake.
Accelerator Pump – Provides additional fuel for sudden engine acceleration.
Economizer Valve (Idle Jet) – Allows the engine to idle when the throttle is closed.
A rich mixture will lower the engine temperature somewhat.
As an aircraft climbs, the mixture automatically gets richer due to the decreasing density of the intake air.
The EGT gauge, on aircraft that have them, is great for adjusting the fuel/air mixture very accurately. The gauge focuses
on relative temperatures rather than absolute.
Peak EGT Temperature = Maximum Economy
Best Power = Maximum Tach = Maximum Airspeed
(This is usually about a 1:12.5 fuel/air ratio, and about 100oF cooler on the rich side).
It is definitely not good for the engine to be running “lean of peak.” You really need a fuel injected engine, and should
have an engine analyzer gauge, if you’re going to do this.
Induction Icing – Impact ice can form on the air induction port when the air temperature is below 0oC. This is most
prevalent around -4oC in air with lots of precipitation or moisture.
Carb Icing – Occurs inside the carb itself. Carb heat comes from air inside the cowling, which passes through a heat
box. In the event of impact ice on the induction port or air filter, carb heat can be used as an alternate air source.
Any time you see a decrease in RPM’s (or a drop in the manifold pressure gauge in a constant speed prop) and you don’t
know why, always apply carb heat immediately. The engine performance may become even more rough, but don’t take
the carb heat off! That’s the carb ice melting.
MOGAS is more susceptible to carb icing than AVGAS.
Throttle Valve Ice occurs most often with a partially closed throttle, and at low power. Most fixed pitch aircraft should
almost always use carb heat below 2100 rpm.
Understand the differences between carb icing, throttle icing and fuel vaporization icing. Throttle icing is one
type/component of carb icing, and fuel icing is the other component. Carb icing, overall, is caused by a
temperature drops inside the carburetor, which can happen even in conditions where other forms of icing cannot occur
on the exterior of the aircraft. The causes of this temperature drop are two-fold. Fuel vaporization icing is due to the
evaporation of fuel inside the carb, and this fuel icing is generally responsible for about 70% of the temperature drop
inside the carburetor. This icing forms on the walls inside the carb. Throttle icing relates to the temperature loss caused
by the acceleration of air and consequent temperature drop specifically around the throttle valve, with ice forming from
water vapor condensing into the throttle valve. Fuel vaporization icing and throttle icing generally occur at the same
time, and they are known collectively as carb icing.
Variable Pitch Propeller Aircraft:
- Throttle controls manifold pressure and therefore engine power.
- Propeller control regulates both the engine RPM and the propeller RPM.
- Setting the power of the engine requires adjustment of both of the above controls. When taking off from an
airport at a high elevation, make sure you lean out to the best power for takeoff!
Fuel Injection Systems:
Only subject to throttle icing. No risk of carb icing (fuel vaporization icing) since fuel is not introduced into the venturi
section of the regulator unit. Fuel is vaporized by nozzles, as it is discharged into the air stream entering the intake
manifold. Throttle is connected to a fuel metering valve. More uniform distribution of fuel to each cylinder. Each cylinder
gets its own supply. - More power since it doesn’t need to heat carb air. Carb icing is not possible. Better fuel economy.
Easier starting in cold weather (but harder in hot).
Vapor Lock – Bubbles of vaporized fuel in the fuel line of a fuel injected engine.
Unlike a carb, you’ll probably want to start a fuel injected engine as rich-lean-rich.
Aircraft can have either 12v or 24v batteries.
Alternators can create current with a fairly low RPM, but generators require a high RPM. Piston engines usually use
alternators, while turbine based engines use generators.
The master switch is a linked switch:
- Battery can be on or off, the position of the alternator doesn’t matter.
- Alternator can only be on if the battery is also on. If the battery is off, the alternator also turns off, regardless of
the position of the switch.
Piston aircraft battery types:
1. Lead Acid Flooded Cell.
2. Acid/Absorbed Glass Mat (AGM). This is a sealed battery. Try not to ever let an AGM get below a 50%
charge.
A negative charge/deflection on the ammeter may indicate that the alternator is not charging the system, and the
battery is carrying the load.
The alternator often puts out 28v (at 60 amps) even though the battery is only 24v, and this output is regulated
appropriately.
A load meter shows the number of amps being drawn.
A very high positive reading on an ammeter possibly indicates that the battery was heavily discharged, and will go away
after a few minutes as the battery takes up a charge. A positive deflection means that the alternator is providing power, a
negative deflection means that the battery is providing power, and zero means no flow.
Voltage Regulator:
- Prevents the alternator from overloading the electrical system.
- Prevents the battery from being overcharged.
Transports (large commercial aircraft) usually use NiCd nickel cadmium batteries.
Reasons for having oil in the engine:
Lubricating, Cooling, Sealing, and Cleaning
Viscosity – The thickness or resistance to flow of a fluid.
Detergent Oil – Normal motor oil, which has additives to keep the engine clean and to keep sludge from forming.
Mineral Oil – A non-detergent oil, normally used to break in a new engine. Often only used during the first fifty hours of
operation.
Oil distribution systems in an engine can either be forced-feed or splash (gravity). If using forced-feed, there are two
types:
- Dry Sump: Uses a separate tank of oil that is forced into and through the crankcase and back by a pump.
- Wet Sump: Oil is contained in the bottom of the crankcase where it is fed through the engine by a pump.
Blow By – A vent for excess oil to be expelled from the engine if it is overfilled or expands too much on heating.
Oil Filters – Only fitted to forced-feed systems. Usually located on the outside of the engine, downstream of the oil
pump.
Pressure Relief – A force fed dry sump has a valve used to help regulate oil pressure in the engine.
A non-congealing oil cooler will prevent overheating by a by-pass that allows the viscous oil to flow and warm up,
then warm up the remaining oil.
Octane Rating Fuel Colors:
Blue: 100LL – low lead. A type of AVGAS.
Green: 100/130 – high lead, rare. A type of AVGAS.
Clear: Jet A. Jet Fuel.
Yellow: Automobile gasoline. MOGAS.
Octane Ratings – When you see two numbers, the first is the octane rating at the lean mixture, and the second is at rich.
Using a lower grade fuel gives you more heptane and less octane, and may lead to detonation.
Octane doesn’t tend to explode, it burns slowly. Heptane, however, is extremely explosive.
AVGAS at 15oC is 6 pounds/US gallon. Jet fuel at that temperature is 7 pounds/US gallon. Fuel gets denser and
heavier as temperature decreases.
Possible additives:
1. Ethylene Dibromide: A cleaning agent, minimizes oxidation on spark plugs.
2. Anti-Icing: Delays the formation of ice crystals.
3. Lead Tetra-Ethylene: Slows combustion.
Baffles in the fuel tanks keep it from sloshing around too much.
Fuel tank vents allow air to come in slowly to prevent a vacuum situation, but also can act as an overflow.
Drain Valves – Allow checking for water, ice, or other contaminants in fuel, and also to drain such contaminants.
Detonation can be caused by leaning too much, or by low octane fuel.
Primer – Vaporizes fuel and sprays it directly into the entrance of the cylinder. Minimizes wear and tear on the starter,
and less battery drain.
Never trust fuel gauges. Do a visual check before every flight.
MOGAS can only be used if the engine has been specifically modified to use it.
You should usually fly with fuel tanks set to “both” unless you’re trying to balance the weight in the aircraft.
In the event of an engine failure, one of the first things you should reach for and change is the position of the fuel
selector.
Fuel pumps can be driven to provide fuel pressure during the start. Electric pumps may be used as a backup on low
winged aircraft.
Supplemental oxygen is used in non-pressurized aircraft that go above 10,000 feet. Rebreather masks are simple but
not very efficient. Used in drop-down systems.
Demand O2 Systems:
- O2 flows into the mask only when inhaled.
- Efficient, non rebreather bag.
- Mask must be firmly seated on the face.
In a pressurized piston airplane, the pressurization is provided by the turbocharger. In a turbine aircraft, bleed air from the
compressor is used to pressurize the cabin.
There is usually an outflow valve and also an emergency dump valve in a plane with a pressurization system.
The differential from sea level to 10,000 feet is 4.6 PSI. From sea level to 35,000 feet is 11.2 PSI. Most planes will have
a maximum pressure differential level, ie. King Air is 4.0 PSI, Airbus is 8.0 PSI. The aircraft has an “internal altimeter”
that you set to the desired cabin pressure.
Differential Pressure – Difference in PSI from the inside to the outside of the airplane.
Cabin Altitude – The equivalent altitude that the cabin is pressurized to. Most transport aircraft set the cabin to 8,000
feet.
Vacuum System – Powers the gyros. Usually engine driven, although classic/heritage aircraft may have a venturi. Often
only has a shelf life of 500 hours. Be prepared, because you’ll lose some of your instruments when this happens (ie.
attitude and heading indicators).
De-Icing Systems – These systems remove ice from critical surfaces during flight. Reactive.
Anti-Icing Systems – Prevent ice from forming in the first place. Proactive. Systems can be fluid, electrical, heating
devices, etc.
Control Riggings – Cable (in most small GA aircraft), pushrods, or “fly by wire.”
THE PITOT-STATIC SYSTEM AND ASSOCIATED INSTRUMENTS
There are two major parts of the pitot-static system: (1) impact pressure chamber and lines; and (2) static pressure
chamber and lines, which provides the source of ambient air pressure for the operation of the altimeter, vertical speed
indicator (vertical velocity indicator), and the airspeed indicator.
Impact Pressure Chamber and Lines
In this system, the impact air pressure (air striking the airplane because of its forward motion) is taken from a pitot tube,
which is mounted either on the leading edge of the wing or on the nose, and aligned to the relative wind. On certain
aircraft, the pitot tube is located on the vertical stabilizer. These locations provide minimum disturbance or turbulence
caused by the motion of the airplane through the air. The static pressure (pressure of the still air) is usually taken from
the static line attached to a vent or vents mounted flush with the side of the fuselage. Airplanes using a flush-type static
source, with two vents, have one vent on each side of the fuselage. This compensates for any possible variation in static
pressure due to erratic changes in airplane attitude.
The openings of both the pitot tube and the static vent should be checked during the preflight inspection to assure that
they are free from obstructions. Clogged or partially clogged openings should be cleaned by a certificated mechanic.
Blowing into these openings is not recommended because this could damage any of the three instruments.
As the airplane moves through the air, the impact pressure on the open pitot tube affects the pressure in the pitot
chamber. Any change of pressure in the pitot chamber is transmitted through a line connected to the airspeed indicator
which utilizes impact pressure for its operation.
Static Pressure Chamber and Lines
The static chamber is vented through small holes to the free undisturbed air, and as the atmospheric pressure increases or
decreases, the pressure in the static chamber changes accordingly. Again, this pressure change is transmitted through lines
to the instruments which utilize static pressure.
Manifold Pressure Gauge – Found on aircraft with a variable pitch propeller (and therefore a fixed RPM). Measures
how much air is allowed to enter the engine for the purpose of combustion. This indicates how much power the engine
might produce, not what it is producing. And it is actually measuring suction, not pressure, because a higher manifold is
lower suction.
To check the Manifold Pressure Gauge:
1. Set an altimeter.
2. Subtract 1 inch Hg (mercury) per 1000 feet AGL.
3. The Manifold Pressure gauge should show close to this value (ie. manifold pressure is lower than altimeter).
Static Manifold Pressure – The pressure before startup. On takeoff, you should see about one inch less of
manifold pressure than static manifold pressure, due to the resistance of the air filter and various bends in the
ductwork.
An engine at full throttle can now draw as much air as it is capable of mixing with fuel and burning, but it will
usually not reach the static manifold pressure value due to intake filter, throttle plate, and ducting bends, etc.
However, it is possible to exceed ambient manifold pressure due to ram air effect.
As long as the engine is running/windmilling, it is sucking air, which is measured as manifold pressure. Manifold
pressure on a dead engine will not drop.
Manifold pressure depends on:
1. Ambient pressure.
2. Position of the throttle plate.
3. Speed of the pistons.
How to detect an induction system leak:
- Engine roughness during ground idle.
- Whistling noise during idle.
- Abnormally high manifold pressure for throttle position.
Bernoulli was concerned with conserving the overall energy of the system (fluid).
Newton was concerned with conserving the overall momentum of the system.
Newton’s law as applied to flight would suggest that since the wing is at an angle to the airflow, the airflow pushes the
wing up by reflecting and bouncing off the bottom, thus the wing is reacting by moving in the opposite direction.
A plane rises because it has excess thrust, not lift (technically speaking).
Lift – The component of aerodynamic force that is perpendicular to the relative airflow.
Aerofoil – The shape of a wing. The bottom is usually flat and the top is usually curved.
Camber – The bend/curve of the top of the wing.
Lift Equation: L = (CL x p x V 2 x S) /2
CL – determined experimentally based on airfoil and angle of attack
p – air density
V – velocity
S – surface area
The drag equation is exactly the same, substituting CD for CL and Drag (D) for Lift (L). An increase in lift always results
in an increase in drag.
Parasitic Drag:
- Caused by parts of the aircraft that do not contribute to lift (antenna, fuselage, struts, landing gear). - Unwanted
resistance.
- Broken down into form drag, skin friction, and interference drag.
Induced Drag – Generated by lift.
Form Drag – Created by the shape of a body.
Skin Friction – Air flowing over a body, which tends to cling to its surface.
Interference Drag – Resistance caused by the effect of one part on another.
To control power in an aircraft with a variable pitch propeller, this means adjusting both the throttle and the propeller
pitch control.
Lift is approximately equal to the angle of attack multiplied by the velocity.
Minimum drag is L/D'MAX = Best Glide Speed or Maximum Range. In the event of a power failure to the engines, you
need to set the aircraft up for this configuration immediately. Parasite drag increases with speed.
Induced drag decreases with speed.
Equilibrium is when lift balances weight and thrust balances drag, and the aircraft is not at rest. A plane is never at
equilibrium in a turn, when accelerating or decelerating, or ascending/descending at a varying speed.
 Load Factor – The total load supported by the wings, divided by the total weight of the airplane. In turn, the weight
of an airplane increases due to centrifugal force.
Resultant Load – The load on the wings when the downward weight of the aircraft is mathematically resolved with
the centrifugal force.
Load factor chart:
15o turn = 1.04 G’s 60o turn = 2.00 G’s
45o turn = 1.41 G’s 75o turn = 4.00 G’s
An aircraft will descend in a turn unless you pull up and increase the angle of attack.
Relative airflow – Always the direction opposite that of the wing’s movement (or aircraft’s movement).
Angle of Attack – Angle between relative airflow and chord line.
Angle of Incidence – Angle at which the wing is mounted to the fuselage.
The Center of Gravity (CoG) is typically located ahead of the Center of Pressure (CoP). The horizontal difference
between where these two forces act through the aircraft is important.
As your angle of attack increases, the center of pressure moves forward. When you stall, the center of pressure moves
back behind the center of gravity, and the plane pitches forward.
Downwash – When the air passes over an airfoil, the air is directed downward. It is an upwash going up in front of the
wing.
Stagnation Points – Calm areas for air at the front of the wing and back of the wing. The stagnation point is what
allows a straight or symmetrical wing/airfoil to generate lift, because it pushes airflow in a way that creates camber.
Airflow below the wings is generally diverted out from the center of the aircraft, and airflow above the wings is
generally diverted inward.
The worst wake turbulence is encountered behind a slow, clean, and heavy aircraft.
Size of wake vortices:
-Two wings span wide and one wing span deep. - Level off about a thousand feet down.
- Settle below and behind at 300-500 feet/minute. - Can often trail by 10-16 nautical miles (NM).
A stalled wing is still generating some lift.
Ground effect:
Downwash deflects more parallel to the surface with Wingtip vortices reduced. Induced drag is reduced, therefore more
thrust, Smaller angle of attack required to generate lift. Within a half wingspan of ground. A heavily loaded airplane may
be unable to “push through” the ground effect. Higher density altitude makes the danger greater of not getting out of
ground effect.
Laminar wings are more susceptible to the effects of icing.
When flying at glide speed:
- Increase speed slightly when flying into a headwind to increase glide range.
- Decrease speed slightly when flying into a tailwind to increase glide range. If you are flying at the best glide speed
and feel that you’re coming in short on landing, pulling up will increase the chance of crashing short. You must fly
at best L/D'MAX speed and/or add throttle.
Force Couples – Equal in magnitude but opposite in direction, ie. thrust and drag in equal amounts, or lift and weight in
equal amounts.
Points of Action:
- Lift – through the center of pressure.
- Weight – through the center of gravity.
- Thrust – through the propulsion system.
- Drag – through the center of pressure and parallel to the relative airflow.
A coarse angle in a fixed-pitch propeller is one that has the prop blades almost horizontal to the ground.
The number of propeller blades is typically between two and six (two on a Cessna). Twin engine aircraft usually have
three or more blades, which are generally shorter.
Multi-Blade Propellers:
-Higher and less objectionable sound frequency. - Greater flywheel effect.
- Reduced vibration. - Improved aircraft performance.
Propeller Twist – Change in blade angle from hub to tip, produces even thrust, because prop speed varies across
diameter. There is a direct relationship, in that twice as far out the prop is twice the rotational velocity of that point.
Propeller Slip – Difference between geometric and effective pitch.
Geometric Pitch – The theoretical distance that a propeller should advance in one rotation.
Effective Pitch – The actual distance that a propeller will advance in one rotation.
Prop Efficiency – Ratio of thrust horsepower to brake horsepower.
Fixed Pitch Propellers:
One piece props with two blades at an unchangeable angle the Pitch must be high enough for good cruising
performance, but low enough for acceptable takeoff and climb; props are economical and lightweight. WHich is
Designed to produce maximum thrust near maximum torque from the engine.
Fine Pitch – Good for takeoff/landing.
Coarse Pitch – Good for cruising. Variable Pitch Propellers are less common than fixed pitch. They have a hub to allow
the blades to change angles.
Effects of a prop:
1. Torque: The prop in a Cessna spins clockwise from the pilot’s perspective. This causes a left yaw during the
takeoff roll. In flight, helical prop-wash strikes the left side of the tail, which again causes a left yaw.
2. Asymmetric Thrust: In level flight, both blades have the same initial angle of attack. If you pitch the nose up,
the right descending blade pitch angle increases, and the left ascending blade pitch angle decreases. Increase
the angle of attack and you increase thrust.
3. Slipstream: The vertical fin and rudder have been installed at a slight angle to align with the airflow, not with the
axis of the aircraft.
4. Gyroscopic Precession: Prop acts like a gyro. Pitching of the nose causes yaw, and yawing of the nose causes
pitching.
A power-off descent will need the left rudder, and the initial takeoff roll or slow flight will need the right rudder.
These are especially applicable in tail-draggers.
Always try to minimize high RPM’s when on the ground, for the sake of the propeller. Do not push or pull on
propellers (90o to the disc of rotation) because it can hurt actuating components. Try to clean props by wiping with
oil if operating near salt water.
Blades should be non-reflective flat black on the side facing the pilot, and color-visible on the front.
Variable Pitch Propeller – The pitch is changed hydraulically with engine oil.
1. Constant Speed: Pitch increases with oil pressure. Usually on a single engine.
2. Constant Speed Full Feathering: Pitch decreases with oil pressure.
3. Manifold Pressure plus RPM setting gives power. A coarse pitch is called a low RPM setting, used for cruising,
and has a big bite. A fine pitch is called a high RPM setting, used for takeoff, and has a small bite.
Feather – A pitch used for eliminating propeller drag during an engine failure (essentially horizontally/flat). Beta –
Neutral thrust.
Reversing – Reverse blade angle. Pushes you backwards, good for landing.
Constant Speed (Non Feathered) permits the pilot to select the propeller pitch and engine speed for any situation, to
automatically maintain the RPM. For economy cruising, the pilot can throttle back to the desired manifold pressure for
cruise conditions, which decreases the pitch of the propeller while maintaining the pilot-selected RPM.
The pilot’s prop valve position directs oil flow to govern the propeller pitch.
On Speed – The RPM automatically stays constant because of oil flow in changing flight conditions.
An overspeed condition results in airspeed increases when the aircraft begins a descent, or when engine power is
increased. If the aircraft begins to climb or engine power is decreased, an underspeed condition results.
Feathering – Achieved through a mechanical linkage that overrides the flyweights and speeder spring.
Unfeathering Accumulator – Permits a feathered propeller to be unfeathered in flight, for air-starting the engine.
Uses compressed nitrogen to keep oil under high pressure during normal flight.
Types of fixed pitch props include cruise, climb, and power (takeoff). With a fixed pitch prop, the RPM will change
in a climb or dive with the initial given power setting:
- Large blade angles will impose a greater load on the engine, slowing it down.
- Small blade angles will unload the engine, allowing it to speed up.
Technically, constant speed and variable pitch are not exactly the same because there are non constant speed props that
can be adjusted in pitch on the ground by hand. But we normally talk about fixed pitch vs. constant speed.
The constant speed prop is now the most common and most efficient prop used in aviation. The pilot will choose a
manifold pressure and prop speed or RPM, the combination of which will give a known power setting. They will then set
it, and let the automation keep it for them.
Flat pitch = Fine pitch = High RPM
Coarse pitch = High pitch = Lower RPM
Governor Failures:
- Single Engine: Moves toward fine pitch.
- Multi Engine: A governor failure or loss of oil pressure causes props to move to feather due to spring and
centrifugal counterweight forces.
When a full feathering prop shuts down, centrifugal latch pins lock the blades in a medium pitch position when RPM’s
drop off, otherwise, it would be hard to start.
Prop Positions when Sitting On Ramp:
1. Single Engine: Full flat pitch, driven by the spring.
2. Twin Engine: Full coarse, but pinned to keep from completely feathering.
3. Free Turbine: Full feather.
Startup:
1. Single Engine: Oil pressure comes up but prop remains in the flat position (prop level fully forward).
2. Twin Engine: Oil pressure comes up and prop blades will be moved to the low-pitch mechanical stops. RPM is
controlled by power.
Run-up:
- Prop lever fully forward.
- RPM 1700-2000.
- Blades will be in full fine (on low pitch stops).
- Prop angle remains constant until prop control is moved back enough to request less than run-up RPM.
- This allows us to check magnetos (mags) without the governor keeping RPM constant. -
RPM will fall when the prop lever is pulled back, due to greater load on the engine.
- Cycling the props allows the governor to be tested, and to circulate fresh oil.
Takeoff:
-Power to full. flat (fine pitch).
- RPM, manifold pressure, and fuel flow checked - Airflow will eventually take load off the engine
on roll. and RPM will increase.
- Initially, RPM near the redline and blades fully - Blades will come off low pitch stops and maintain
selected RPM for takeoff.
Engine Failure in a Twin Engine:
- RPM on a failed engine stays the same as the running engine.
- Most gauges (manifold pressure, RPM, oil pressure, oil temp) except for the EGT will show few changes.
- The windmilling prop is enough to power the governor.
Wing Planform – The shape of the wing when viewed from above.
Chord – Imaginary line from the leading edge to the trailing edge.
Aspect Ratio = Span divided by chord.
- High ratio: Low induced drag, high parasite drag.
- Low Ratio: High induced drag, low parasite drag.
Camber – The curve of an airfoil. If the lower surface of the airfoil is curved downward, then we would refer to it as
negative camber.
Laminar Flow – Smooth airflow over the wing.
Laminar Flow Wing – A design that moves the transition point further aft, which reduces the drag of the wing (and lift).
Maximum camber is located further back. During a stall, a laminar flow wing won’t pitch forward as well as a regular
wing.
Sweepback Wing – Designed for high speed operations to delay the onset of supersonic shock waves. Performs poorly
at low speeds. Swept wings may get slats, slots, and extra flaps.
Dihedral – The “V” look of wings when viewed from the back of the aircraft, ie. the upward angle from the wing root
to the wing tip. Higher dihedral increases lateral stability by helping prevent roll.
Anhedral – Opposite of dihedral, wings are droopy.
Washout – A twisted wing. The angle of incidence at the wingtip is less than it is at the wing root.
Slats – Small airfoils that open in the front of the wing, to smooth airflow over the wing.
Slots – Openings built into the leading edge of the wing that allow the high pressure air to pass through it at a high
angle of attack and increase the lift.
Spoiler – Destroys lift by causing the airflow to separate from the top of the wing. Can assist with braking. Spoilerons
– Spoilers that assist with aileron control.
Reasons for Flaps:
-Increase lift and drag by increasing camber. airspeed.
- Steeper approach angle without increasing - Reduces stall speed.
- Increase in forward visibility.
Vortex Generators – Placed along the span approximately ten percent aft of the leading edge of the wing to create a tiny
vortex in the air stream over the airfoil. This vortex energizes the normally stagnant boundary layer of air on the wing’s
upper surface. Surprisingly, an energized boundary layer is more resistant to flow
separation than a stagnant boundary layer, so airflow sticks to the wing longer, permitting flight at lower airspeeds
and a higher angle of attack, and improving control authority.
Winglets – Vertical tabs at wingtips that increase the effective wing span of an airplane by reducing induced drag.
Canard – An aerofoil mounted in front of the wing that produces lift upwards, whereas stabilizers produce a
negative lift. Can be fixed or controllable. An airplane with a canard will not enter a full stall.
Load Factor – What our aircraft thinks it weighs.
Some maneuvers increase a plane’s stalling speed, especially those that somehow accelerate the aircraft.
The best (most efficient) way to increase lift in a turn (to prevent losing altitude) is to pitch up, rather than to add
throttle. Be careful though, because it increases your angle of attack. So add a tiny bit of power in a steeper turn.
Considering and accounting for turns is a critical skill for a pilot. The most important time to do this is in the
circuit.
A late turn to the final, coupled with increased rudder and aileron, can lead to a spin. This is one of the biggest
dangers for private/recreational and other pilots! These accidents occur with a greater frequency with a crosswind
that pushes you past the runway on a turn from base to final.
If you’re slow, especially in slow flight with flaps on, the wind will probably be coming up at you with a high angle
of attack.
Stall speed in turns: V S(turn) = V S x square root of Load Factor (VST)
Negative Load Factor – Caused by upward centrifugal force that decreases the G load to less than one.
Maneuvering Speed (VA) – The maximum speed at which the aircraft can be safely stalled. It will be greater for
increased weights. This is a simple multiplier formula. V A = V S x 1.7
Make sure you memorize this for maximum weight and also for a couple of lower weights.
A combination of flight controls or gust loads created by turbulence should not create an excessive load factor if the
airplane is operated below V A. The aircraft will stall before the acceleration can produce a damaging load.
Load Limit – The load factor that the pilot must keep the aircraft within. Above this load, the aircraft will sustain
damage or failure.
Ultimate Load – The aircraft is designed and certified to withstand 1.5x the load limit.
Load Limit Chart:
Normal, + load limit = 3.8G Utility, - load limit = 1.76G
Normal, - load limit = 1.52G Aerobatic, + load limit = 6.0G
Utility, + load limit = 4.4G Aerobatic, - load limit = 3.0G
Types of Operations:
- Standard: Few restrictions, but cannot be used for airline or commuter operations.
- Restricted: One purpose only, no passengers, need a “restricted” and “no passenger” sign, an example
would be an aerial application aircraft.
- Experimental: Used for testing, or homebuilt. Passengers allowed. Need a placard to state that the aircraft has not
gone through a certification process.
Stability – The ability of an aircraft to remain in a position or attitude during flight and then return to a given position
or attitude following a disturbance.
Types of Stability:
- Positive Stability: Like a ball in a bowl. Always returns to its original position following a
displacement or disturbance.
- Neutral Stability: When displaced, it remains in its new position.
- Negative Stability: Like a ball on an upside down bowl. The slightest displacement will cause it to continue to
move in that direction, sometimes at an accelerating rate.
Static Stability – Initial tendency of an aircraft to return to its original position directly.
Dynamic Stability – The overall tendency of the aircraft to return to its original position following a series of
oscillations.
Stability Around an Axis :
-This is a bit confusing, so memorize it. - Lateral stability is around the longitudinal axis.
- Longitudinal stability is around the lateral axis. - Directional stability is around the normal axis.
Longitudinal Stability:
- Affected by the size and position of the horizontal stabilizer and the position of the center of gravity. - An aircraft
that is nose-heavy is more stable.
- This is also known as pitch stability (because it is around the lateral axis).
Lateral Stability:
- Trainers are positive, aerobatic planes are neutral or negative.
- Best lateral stability is achieved by dihedral, sweepback, keel effect, and proper distribution of weight.
- Also known as roll stability (because it is around the longitudinal axis).
Directional Stability:
- Stability around the vertical axis.
- Achieved by tail surfaces, fin and rudder, keel effect, and sweepback.
- Also known as yaw stability (because it is around the normal axis).
Stabilator – When the entire stabilizer moves in response to elevator control pressure.
Aileron Drag – Created because of the greater drag of the down-going aileron causing yaw in the direction opposite of
roll. This is one type of adverse yaw.
Frise Aileron – Has an offset hinge, is used to reduce aileron drag. The leading edge of the up-going ailerons moves into
the oncoming airflow below the wing. The lower lip catches the airflow. It also forms a slot, making it effective at low
airspeeds.
Differential Ailerons – The up-going aileron is moved higher than the down-going aileron. It is used to reduce
aileron drag.
Dynamic Balance Controls – Allow the pilot to move the controls more easily.
Mass Balance – Used to counteract flutter by positioning a weight ahead of the hinge. Mounted either internally
or externally on the airplane’s control surface.
Static Balance – When, in a situation with no airflow, the control surface’s center of gravity is in the
manufacturer’s specified location.
When flaps go down, the nose goes up!
The more a pilot uses trim, the better the pilot. All airplanes have elevator trim, but some also have rudder and
aileron trim.
Balancing Tab – Similar to a trim tab, coupled to the control surface. When the control surface is moved, the
balancing tab is automatically moved in the opposite direction. Servo Tab – Used on large airplanes. The tab is
moved directly by the pilot, then the force of the airflow on the servo tab moves the control surface.
The Pilot-In-Command (PIC) is basically responsible for everything, including:
-Airworthiness of the aircraft. - Briefing of passengers.
- Knowing the forecast weather. - Avoiding restricted airspace, following all CARS.
- Up-to-date charts and safety equipment.
Clean Aircraft Concept – Takeoff is prohibited when frost, ice, or snow is adhering to any critical surface of the
aircraft.
Cold Soaking – Occurs when an aircraft travels from warm to cold to warm, which might cause condensation and ice to
build up on the aircraft’s skin.
In-Flight Airframe Contamination:
- Occurs when you have visible moisture and a sub-zero temperature.
- Ice on Wing: Loss of lift.
- Ice on Prop: Vibration.
- Ice on Windshield: Loss of vision.
A high reliance must be placed on flight instruments during whiteout conditions. You are essentially IFR.
Severe turbulence can extend 20NM from a storm. Also, getting hit by lightning is not great. Avoid thunderstorms.
Mountain Flying:
- Rapidly changing and unpredictable weather.
- Downdrafts are most common on the shaded side, and updrafts are most common on the sunny side.
- Be able to complete a “maximum rate with minimum radius” turn at all times.
- Remember that ceilings and performance figures are all based on density altitudes.
Don’t use strobe lights while taxiing or during flight in clouds.
Canadian Runway Friction Index (CRFI):
- CRFI of 1.0 is the maximum runway coefficient, ie. bare and dry. Perfect braking. - A low
CRFI of 0.1 to 0.3 would probably indicate an ice-covered, slippery runway. - Obtained from
ATIS, NOTAMs, FSS.
- The “increase in landing distance” chart can be very useful.
VASIS – Visual Approach Slope Indicator System.
PAPI – Precision Approach Path Indicator.
A good approach slope is three degrees.
There are three main types of runway lighting:
- Two bar VASI: Good when you have red over white.
- Three bar VASI: “White over white, fly all night … red over red, you’re dead.”
- PAPI: The better modern system.
If you’re looking at a three-bar VASI system and you’re in a small GA aircraft, ignore the top row of lights and pretend
that the bottom two rows are a standard two-bar VASI system. Only large jets use all three (or use just the top two rows).
PAPI System – Uses four bars, horizontally. The same rhyme works as for 3-bar VASI. A perfect approach is two white
and two red bars, side by side. This system is currently replacing VASI systems.
Minimum runway requirements at night:
- White X’s on a runway mean that it is closed (white for visibility, instead of red). - Yellow
chevrons on a runway indicate that it is non load-bearing, do not use.
- White arrows mean displaced threshold, land further up past the threshold.

Towers (not ATC Control) affecting cross-country navigation:

- Under 1000 feet have steady red lights.
- Above 1000 feet have white strobes.
- Check NOTAMs and the flight planning section in the CFS.
Memorize your marshaling signals. Can probably be found in “From The Ground Up.”
Wheelbarrowing – Landing on the nose wheel because you’re coming in too fast.
Porpoising – Aircraft bounces alternatively off main wheels then nose/tailwheel. Use back pressure to get a proper
landing attitude.
Rotating tires hydroplane at up to 9x the square root of the tire pressure in PSI.
Non-rotating tires hydroplane at up to 7.7x the square root of the tire pressure in PSI.
To recover from wind shear, prompt action is required. Use full power, and pitch up to maximum angle of attack.
High density altitude probably means low pressure.
Four factors affecting the density of air include:
-Barometric pressure. - Temperature.
- Altitude. - Humidity.
Humidity is not good for air density (lighter) because the molecular weight of vaporized H2O is less than that of O2 or
N2. Air density decreases with barometric pressure decrease, but also
with increases in air temperature, altitude, or humidity.
Service ceilings, absolute ceilings, and leaning settings for aircraft are all given in terms of density altitudes.
Lower air density causes:
- Less engine power.
- Less propeller thrust.
- Less lift produced by wings.
Ground effect reduces the amount of induced drag.
VX is the Best Angle of Climbing:
- Best used for takeoffs over obstacles.
- This speed changes with altitude, and increases as the altitude increases.
- Equal to L/D at the aircraft’s ceiling.
VY is the Best Rate of Climbing:
- Changes with altitude, becoming smaller (IAS) as we climb.
- At the aircraft’s ceiling, it is the same as the L/D speed.
When an aircraft is at its absolute ceiling, then:
Best L/D = V X = V Y = VG
VA is the Maneuvering speed. This is the maximum speed at which it is safe to use full deflection of the controls. The
aircraft will sustain structural damage if operated at speeds above V A, due to increased load factor. This speed varies with
weight; it is higher when the aircraft is heavier. Always operate below VA during turbulence.
VNE – Never exceed this speed. If you do, your aircraft automatically becomes non-airworthy until inspected by an AME.
VFE – Maximum flaps extended speed. Indicated by the top of the white arc on the airspeed indicator. V SO – Stalling speed
with flaps fully extended. This is the bottom of the white arc on the airspeed indicator.
Indicated vs. True stalling speed:
- Indicated stalling speed always stays the same.
- True stalling speed increases with altitude.
- Indicated and true stalling speeds are equivalent at sea level.
Although you don’t have to do a spin dive recovery on your flight test, you may have to verbalize how to recover.
The faster the speed of the aircraft, the steeper the bank angle required to maintain a standard rate turn.
Nose-heavy center of gravity:
- Needs more trim. stabilizer.
- Is more stable. - An aft-heavy center of gravity would be the
- Flies slightly slower. opposite of all of the above.
- More drag, due to more tail pressure on the
A few millimeters of ice can increase the stalling speed by as much as 20%.
Ice accumulation with the thickness/coarseness of medium/coarse sandpaper will:
1.Decrease lift by up to 30%.
2. Decrease drag by up to 40%.
The Coefficient of Lift (CL) is based upon the angle of attack and the shape of the airfoil. Performance charts are obtained
by pilots in brand new aircraft.
Types of chart
1.Takeoff distance.
2. Cruise.
3. Fuel burn.
4. Climb.
5. Wind component and CRFI.
Always remember to read conditions/notes and to apply corrections in order. Takeoff distances are longer than landing
distances. Getting in safely is fine, but getting back out is what is ultimately most important.
Short Field Technique – Use full throttle prior to releasing your brakes.
Almost all performance charts require using pressure altitude equivalents.
Pressure altitude is extremely important. It is used to determine density altitude, true altitude, and true airspeed. One
method of calculating the pressure altitude is to physically set the altimeter to 29.92 and then read the pressure altitude
right off the dial. The second method, which would be useful during an exam when you don’t have access to an altimeter,
is:
1. Subtract the current altimeter setting from 29.92.
2. Multiply by 1000.
3. If positive, add the number to the actual elevation. If negative, subtract the absolute value from the elevation.
Problems with an overloaded aircraft include:
-Higher takeoff speed, longer takeoff run. - Reduced maneuverability.
- Reduced rate of climb. - Higher stalling speed.
- Decreased range. - Higher approach/landing speed.
- Reduced cruising speed. - Longer landing roll/stopping.
Standard Empty Weight – The weight of the airplane plus oil and unusable fuel, without equipment.
Basic Empty Weight – The standard empty weight plus equipment.
Maximum Takeoff Weight – The heaviest that a fully loaded plane can weigh, including fuel, cargo, pilot and
passengers, and equipment.
Useful Load – Maximum takeoff weight less basic empty weight.
Maximum Ramp Weight – This might be a few pounds heavier than the maximum takeoff weight, to allow for an extra
gallon or so of fuel that will be burned off by taxiing before takeoff.
Important Fuel Weights:
- AVGAS is 6 pounds per US gallon.
- OIL(65) is 7.5 pounds per US gallon.
A US gallon is 3.785 liters.
Zero Fuel Weight – Basic empty weight, crew, passengers, cargo, oil, and unusable fuel. But no usable fuel.
Maximum Zero Fuel Weight – Max weight before the rest must be fuel.
Datum Line – An arbitrarily selected point (set by the manufacturer) from which all horizontal distances are measured
for weight and balance reports. This point is not the same as the fulcrum.
Moment = Weight x Arm (inch-pounds).
The moment is often listed in the 1000's on charts, including on Cessna charts.
Mean Aerodynamic Chord (MAC) – The center of gravity is often expressed as a percentage of the average chord of
the wing. Usually used for large commercial aircraft.
Methods of Determining Weight & Balance:
-Center of Gravity calculations. - Center of Gravity charts.
- Center of Gravity graphs. - Loading Schedules (placards).
For center of gravity calculations, add up all the weights and moments, then divide moments by weights.
Arms that are “aft” of (behind) the datum point are considered positive, and if they are “fore” (ahead) of the datum point
they are negative.
Moment Loading Envelope – A graphical depiction to see if the moment arm falls within acceptable limits.
Center of Gravity Envelope – A graphical representation which shows the center of gravity in terms of inches aft of the
datum line. Anything outside of the limits on the left side of the graph means that the center of gravity is too far forward,
and outside on the right is too far aft. Do not fly with your center of gravity outside of the envelope. It is very risky and
potentially fatal.
If the aircraft is tail heavy:
You’ll need a nose-down trim, It will be less stable More susceptible to gusts. It will cruise faster.
Always calculate two weight and balance reports for each flight, one for takeoff and one for landing. You’ll burn fuel
during the flight, which will slowly shift the location of the center of gravity. As a pilot, you should know whether the
center of gravity moves forward or aft as the fuel is burned.
LEMAC – Leading Edge MAC
TEMAC – Trailing Edge MAC
A percentage MAC position is the distance that the center of gravity is located behind the LEMAC in comparison to the
TEMAC. Usually between about 10% to 30%, and 25% is a common measurement.
The fulcrum is located at the center of the lift.
Weight Turbulence Categories:
- Light is less than 15,500 pounds.
- Medium is 15,500 to 300,000 pounds.
- It weighs more than 300,000 pounds.
Search and Rescue Coordination Centers (REC) are located in Victoria, Trenton (Ontario), and Halifax.
SAR puts an airplane in the air at one hour past the end of the ETA in your flight plan. However, the investigation starts
only a few minutes after your ETA has been exceeded. Always remember to amend your flight plan in-air if you think
you’re going to be delayed, even if you’re only going to be a few minutes late.
Aiding Persons in Distress:
- Keep the distressed craft in sight as long as possible.
- Report the following to ATC: Time of observation, position of craft, general description of the scene, possible
medical/triage info.
Radar Alerting:
- Squawk 7700 on the transponder.
- Monitor emergency frequencies.
- If you don’t have two-way radio communication, and can only communicate through a transponder location,
signal by flying two triangles, resume course, repeat at five minute intervals. - If your radio only has receive (RX)
functions but ATC cannot hear you, fly to the right on your two triangles.
- If your radio has neither transmit (TX) nor receive, fly to the left on your two triangles. - Fly two minute legs
for the sides of your triangles when your airspeed is less than 300 KTS, or one minute legs for speeds
exceeding 300 KTS.
Although SAR is launched very quickly, the average SAR response time (for successful arrival at distressed aircraft)
is twenty-four hours. Be prepared!
Three fires arranged in a triangle is the standard distress signal.
Three instruments are connected to the
Pitot-Static System:
- Altimeter (ALT)
- Vertical Speed Indicator (VSI)
- Airspeed Indicator (ASI)
Pitot Tube – Uses ram air, and is usually heated. This is to prevent icing, not specifically to heat the air. The ASI is the
only instrument directly linked to this tube. The pitot tube must be heated for IFR flight.
Static Port – Needs normal (not forced) air. Attached to ALT, VSI, ASI. If the static port becomes blocked, the ALT and
VSI will freeze. The ASI will read incorrectly. Airspeed will under-read in a climb and over-read in a descent.
If the pitot tube becomes blocked, the effect depends on whether the blockage is partial or complete.
Complete pitot blockage:
- Airspeed reads high in a climb.
- Airspeed reads low in a descent.
- ASI acts like an altimeter.
Partial pitot blockage:
- ASI will decrease to zero.
Indicated Airspeed (IAS) – Speed through the air. The airplane knows this, not how fast the ground is going underneath.
Variations include MIAS for mph, and KIAS for knots/hour.
Ground Speed – Indicated airspeed plus a wind component.
Airspeed Indicator – Measures the difference between the dynamic (pitot) and static pressure. This is read as indicated
airspeed on the instrument. Contains a diaphragm which is connected to the IAS needle through a system of pulleys and
levers.
Possible airspeed indicator errors:
-Positional error. - Ice or water blocking the pitot tube.
- Compressibility error.
- Density error.
Calibrated Airspeed (CAS) – Accounts for positional error.
Equivalent Airspeed (EAS) – Takes into account compressibility. Only encountered in aircraft that travel at very high
airspeeds, over 250 knots.
True Airspeed (TAS) – Accounts for density errors, which are caused by changes in air density (affected by altitude and
temperature). A rule of thumb is to add 2% to IAS for every thousand feet of pressure altitude. Involves using a flight
computer, rule of thumb, or true airspeed indicator.
Positional Error:
-Caused by the position of the pitot. - Angle of air hitting the pitot leads to additional
- Pitot needs to be placed as far as possible ahead pitot error.
of the wing’s leading edge. - When the IAS is corrected for positional error, we
get the CAS.
Cruise Standard – Having the aircraft at “cruise” altitude, plus the throttle set at 2200 RPM’s, probably gives you about
90 knots in a Cessna 172.
Approach Standard – Having the aircraft at the “approach” attitude plus 1500 RPM is probably going to give you about
65 knots in a Cessna 172 descending at 500 feet/minute.
Airspeed Indicator Markings:
The “top” of any arc means the fastest recommended or permitted airspeed, and the “bottom” of an arc means the
slowest. The white arc is associated with flaps usage.
- V SO is the stall speed with flaps fully extended.
- V S1 is the stall speed with no flaps.
- V FE is the maximum speed with flaps extended.
- The green arc is the recommended safe airspeed range.
- The yellow arc is the caution range for velocity, which you should only use if absolutely necessary, and only in
calm, non-turbulent conditions.
- V NO is the maximum recommended IAS for normal operations.
- V NE is the “never exceed” speed (the red line).
- Blue lines are found on multi-engine aircraft. Associated with the best single-engine rate of climb speed
(VYSE) which should be maintained in the event of an engine failure.
Airspeed can be in MPH, km/hr, or Knots. Probably MPH in a Cessna. Metrics (km/hr) are very uncommon.
Think of “iced tea” when moving between airspeed conversions: I-C-E-T
 Indicated Airspeed 🡪 Calibrated (POH) 🡪 Equivalent (if >250KT) 🡪 True Airspeed
Our true airspeed at the stall is always higher at high altitudes or high temperatures. It only matches the IAS at sea
level and at standard temperature.
Tape Type Airspeed Indicator (TAA) – Found on more advanced Garmin or Avidine flight panels. On a TAA, “G”
stands for general cruising speed and “R” stands for rotation speed. If you see a pink vector bar on the side, it shows
what your speed will be in six seconds. MFD – Multi Function Display.
Other important velocities:
- V R – Rotation speed.
- VA – Maneuvering speed. Changes with weight! Increases as weight increases. This is the maximum speed at
which we can exert full controls without damaging the airplane. You do not want to exceed your maximum
load factor.
- V DIVE – Speed at which things start to shake, and maybe fall apart. V NE = V DIVE x 0.9, V NE makes an aircraft
non-airworthy.
- V LE – Maximum speed with retractable flaps extended.
- V LO – Maximum speed at which you can extend or retract the gear. It is always slower than V LE by necessity.
- V S – This changes with changes in the center of gravity.
The “dirty” configuration means flaps are down/extended. Clean means flaps are up/retracted. Vertical Speed Indicator
(VSI) – Connected to the static port. Similar to the altimeter. Contains a small calibrated hole in the instrument case that
allows the pressure to slowly leak out. Possible errors in the VSI:
- Lag Error: Largest error. The VSI is a trend instrument, not an instantaneous one. It usually lags by about six to
eight seconds.
- Reversal Error: A sharp and sudden pitch change will temporarily show the opposite of what the airplane is
doing.
The ideal descent rate for approach on landing is 500 feet/minute in a small GA aircraft.
In an altimeter, the pressure in the sealed aneroid is at 29.92” Hg. This is “inches of mercury” and is known as
Standard Pressure. An altimeter is an aneroid barometer. It is connected only to the static port. The
A common type in a small GA aircraft has three hands, similar to the concept of hands on a clock, and is called a
Three Point Altimeter.
Drum Altimeter – Has an analogue dial rather than sweep hands, so it looks like an odometer.
Kollsman Window – The altimeter setting window on a pressure altimeter.
The altimeter only works correctly under these conditions:
-Must be at sea level. - Temperature must be 15oC.
- Air must be dry (no humidity). - Temperature decreases at 1.98oC per 1000 feet.
- Barometric Pressure must be 29.92”. - We lose 1” of pressure per 1000 feet.
If you don’t have an outside pressure reading, you can set the altimeter to whatever reading gives you the proper
elevation of the field.
ISA – Standard Atmosphere
If flying into a high or low pressure system, remember the following: “From high to low, look out below.”
If you’re doing cross-country, you need to keep getting local pressure setting and making adjustments to the altimeter.
An altimeter setting that is too high will give a reading that is too high.
Low systems have counter-clockwise flows.
The highest setting on most altimeters is 31.00” Hg. However, actual pressure can certainly be higher. Just set it to
31.00” Hg. You’ll be Ok because this error is in the “safe” direction, and you won’t fly into the ground accidentally. For
the same change in pressure, warm air will have a greater vertical depth (spread) than cold air.
Cold Correction Chart – Shows us how incorrect our indicated altitude can be in very cold conditions.
Mountain Effect – Due to Bernoulli’s Principle, air that is deflected around mountains will increase in speed and
decrease in local pressure. It will give an altitude reading that is too high! This is dangerous.
Mountain wave winds can extend for as much as 700 miles downwind of mountains. They can feature low pressure and
severe downdrafts! They are most severe near the summit of the mountain. Downdrafts can run at more than 5000
feet/minute vertically.
Any time you fly in the mountains, you should fly much higher than you think you need to be.
Indicated Altitude – What we see on the instrument. It depends on the accuracy of the Kollsman value.
Pressure Altitude – What is indicated when the Kollsman is set to 29.92, or Standard Atmosphere. This is
extremely important, and is used to determine things like density altitude and true airspeed.
True Altitude – The exact height above means sea level. True altitude corrections need to include a correction for
 non-standard temperatures, and true altitude is important when we are trying to figure out if we have enough
obstacle clearance. To calculate true altitude, use the left side of the E6B, then line up the outside air temperature
and pressure altitude.
Absolute Altitude – The actual height above ground surface (AGL) with the altimeter correctly set and non standard
variations in temperature taken into consideration. To calculate the absolute altitude, find the true altitude, then subtract
the height of the terrain below.
Density Altitude – Pressure altitude corrected for non-standard temperature. Our aircraft performs as if it is at this
level. Density altitude gives us the density of the air. Therefore, it tells us how the aircraft will perform. All service
ceilings and absolute ceilings are given in terms of density altitudes.
A lot of people get confused by Density Altitude, and think that a higher density altitude means that the air has a higher
density. However, when you think of the phrase “high density altitude,” don’t be tricked by the fact that “high” and
“density” are together. In a “high density altitude,” the “high” refers to the “altitude,” and of course at higher altitudes,
the air is thinner. Encoding Altimeter:
- Linked to transponder. - Known as Mode C.
- Allows ATC to know pressure altitude as well as - Controller sees a pressure altitude.
position.
The magnetic compass is the only basic instrument (ignoring GPS) that helps determine the direction of flight.
Cardinal Points – North, South, East, West.
The Magnetic Compass case is filled with white kerosene. This dampens vibrations or oscillations. The center of
buoyancy is above the center of gravity to minimize dip at higher latitudes. This dip occurs because magnetic lines of
force are fairly horizontal at the equator and fairly vertical at the poles.
Lubber Line – Direction marker line (vertical) on the magnetic compass.
Isogonic Lines – Lines of equal magnetic variation.
Agonic Line – The isogonic line of 0o variation. This currently passes in a north/south orientation just west of Thunder
Bay.
Deviation – Error for a compass installed in an aircraft versus what it would read if outside the aircraft, caused by metal
and RF instruments in the aircraft. Deviation errors are usually only a couple degrees, but you should still take them into
account for navigation.
Variation – The difference between magnetic north and true north. This is also sometimes called Magnetic Declination,
but be careful that you don’t confuse declination with deviation. It’s better for aviators to use variance instead of
declination.
The west side of Canada has an easterly variation, and the east side has a westerly variation. We need to correct for
variations in our navigation logs.
Converting from True to Magnetic – Subtract easterly from true to get magnetic, or add if westerly. Remember this
phrase, “East is least, west is best.”
To convert from True to Magnetic to Compass:
1. Start at True, and adjust for winds if necessary.
2. Come up with Magnetic by accounting for variation.
3. Come up with a Compass by accounting for deviation.
Remember that a magnetic compass reads “backwards,” ie. higher numbers on the left.
Northerly Turning Error – On turns from the north, the compass will lag, and on turns from the south, the compass will
lead. Also, from the north, the compass will initially turn in the wrong direction before correcting. This of it this way: A
compass normally “wants” to point north. That is also its tendency during the turn. This northerly turning error is caused
by magnetic dip.
Acceleration/Deceleration Errors – If flying east or west, accelerating the aircraft will cause the compass to register a
turn to the north. Deceleration registers a false turn to the south. Again, you can remember this by thinking about the
compass being “excited” by acceleration and wanting to turn north.
The magnetic compass only gives you a correct reading when in a wings-level attitude at a constant airspeed. Note that it
can be accurate in a constant speed wings-level climb or descent. The altitude does not have to remain constant, as long
as there is no acceleration or deceleration in the climb/descent.
Gyroscope – Any rotor, disc, or wheel spinning at high speed. Even automobile wheels are an example.
Gimbal – A universal mounting device for a gyro that allows its axis to be pointed in any direction.
When a gyro is rotating, it resists changes in direction. It has two predominant characteristics: rigidity in space, and
precession.
Rigidity in Space – Once set into motion and spinning, gyroscopes resist turning. When gimbaled (in one, two, or
 three dimensions) any surface such as an instrument dial attached to that gyro assembly will also remain “rigid” in
space.
Precession – The deflection of a spinning wheel 90o to the plane of rotation, when a deflective force is applied at
the rim.
Gyro instruments can be vacuum or electrically driven. They include:
- Turn coordinator: usually electric.
- Attitude indicator: usually vacuum.
- Heading indicator: usually vacuum.
Vacuum driven systems generally need 4-6 inches of mercury to operate. They can be engine or venturi driven.
There is probably a little red flag in the turn coordinator (and other instruments) that is visible only when there is no
power, so this acts as a warning if the electrical fails.
The attitude indicator is the primary instrument in instrument flying.
Heading Indicator (HDI):
Sometimes known as the Directional Gyro. Only valid when set by magnetic compass. Needs to be set at the start of
each flight, and approximately every fifteen minutes thereafter in regular, non-accelerated flights. Vacuum powered
gyroscope. Unaffected by acceleration, deceleration, or turns. Need to adjust for both apparent precession and frictional
precession. Check the HDI again the runway number as you line up. Frictional precession relates to friction in the gimbal
bearings. Apparent precession occurs because even though you might feel that you’re flying in a straight line, you’re
actually traveling in an arc over the earth’s surface. You may see an error of up to fifteen degrees per hour of flight.
Tumbling – When the HDI loses its gyroscopic characteristics after being subjected to severe maneuvers. Can often
happen after exceeding 55o of either pitch or bank.
Glass Panel HDI – Can show a 360o circle or a 140o arc. Options to show GPS, VOR, ADF, and ILS info are possible.
Relies on an AHRS system. Attitude and Heading Reference System (AHRS) – Gyroscope is replaced by lasers,
accelerometers, and magnetometers.
Attitude Indicator (ATT):
- Vacuum driven gyroscope.
- Can be electrically driven.
- Gimbal mounted on a vertical axis.
VY in a Cessna 152/172 is typically very close to eight degrees pitch.
Most descents in light GA aircraft are between 3o and 5o pitch down.
Pull To Cage – A setting that locks a gyro into place and prevents tumbling during aerobatics, etc.
Attitude Indicator errors:
- Acceleration will indicate a climb.
- Deceleration will indicate a descent.
Turn & Bank Indicator:
Older style of instrument, usually replaced nowadays with a Turn Coordinator. Uses an indicator needle with a
left/right deflection instead of the visual representation of a small airplane that you’d see in a turn coordinator. Can
only identify yaw, but not rolling.
- Lags slightly (by about one second).
- Two components: turn needle and doghouse.
- Doghouse has a mark on either side of the center that represents a standard rate turn.
Turn Coordinator:
Two parts, the visual silhouette of the aircraft, and the “ball” (inclinometer). The purpose is to indicate the rate of turn
and the quality of the turn. Can identify both yawing and rolling motions. (Usually electrically powered. ) No lag. Red
flag appears if it loses electrical power.
Inclinometer:
Glass level containing a black ball. Provides the pilot with a measure of the turn quality. The ball should stay centered
during both straight & level flight, and during turns! Otherwise, you are slipping or skidding.
Skid:
Too much rudder for a given bank angle. The tail end of the plane swings to the outside, The ball is on the opposite side
to the lowered wing. “Step on the ball” is the catchphrase, although you might need to release the opposite rudder.
Slip
A turn where insufficient rudder is being applied. The ball is on the same side as the lowered wing (or needle). Also too
much bank/aileron for the current amount of rudder. You can fix this by applying additional rudder OR reducing the bank
angle.
In a turn coordinator, the gyro spins up and away from you. The gyro spin axis is angled or canted 30o to the horizontal.
This makes it capable of responding to both yaw and roll.
Standard Rate Turn:
- If your airspeed is faster, your bank angle needs to be higher in order to complete the turn in time. - The rule
of thumb for bank angle is (KIAS/10) + 7, ie. 120 KTS = 19o bank.
- For MPH, use (MIAS/10) + 5, ie. 140 MPH = 19o bank.
While learning to fly, learn to fly by looking outside, and by knowing your attitudes. Pay some attention to the instrument
panel, but not too much!
The three fundamental skills are Scan, Interpret, and Control.
Scanning Instruments – Do continuous cross-checking. Common errors include fixation, omission, or over
emphasizing one instrument’s indication.
Partial Panel – When you’re flying without all six of your instruments. Usually, your vacuum system is the most
likely system to fail, so you’re probably flying without your attitude indicator and heading indicator when flying a
partial panel.
Unusual Attitudes – Any unexpected rate or instrument indication contrary to what you would have expected.
Nose Up AND Nose Down Recovery Considerations:
- Use ASI and TC as your primary instruments. - The ATT and HDI may have toppled, so they may
- Pay attention to the trend of the ASI. be unreliable.
- The ALT and VSI may be unreliable due to la

To effect a Nose Up recovery:

1. Go to full power.
2. Put the nose down until the ASI stops decreasing.
3. Level wings based on TC.
4. Reduce power to cruise.
5. Cross check the instruments.
To effect a Nose Down recovery:
1. Power off.
2. Level wings based on TC.
3. Nose up until the ASI stops increasing.
4. Add throttle to return to cruise power.
5. Cross check the instruments.
CHAPTER 2 - AIRPLANE & ENGINE
AIRPLANE STRUCTURE
the required structural strength is based on the intended use of the airplane. An airplane which is to be used for normal
flying does not need the strength of an airplane which is intended to be used for acrobatic flight or other special purposes,
some of which involve significant in-flight stresses.
Numerous wing designs have been developed in an effort to determine the best type for a specific purpose. Basically, all
wings are similar to those used by the Wright brothers and other pioneers. Modifications have been made, however, to
increase lifting capacity, reduce drag, increase structural strength, and generally improve flight characteristics. Wing
designs are subjected to thorough analysis before being approved for use on certificated airplanes. Strength tests
determine the effect of strains and stresses which might be encountered in flight.
Airplane strength is measured basically by the total load which the wings are capable of carrying without permanent
damage to the wing structure. The load imposed upon the wings depends upon the type of flight in which the airplane is
engaged. The wing must support not only the weight of the airplane, but the additional loads caused during certain flight
maneuvers such as turns and pullouts from dives. Turbulent air also creates additional loads and these loads increase as
the severity of the turbulence increases.
To permit the utmost efficiency of construction without sacrificing safety, the FAA has established several categories of
airplanes with minimum strength requirements for each. Limitations of each airplane are available to the pilot through
markings on instruments, placards on instrument panels, operating limitations attached to Airworthiness Certificates,
Aircraft Flight Manual, or Pilot’s Operating Handbook.
FLIGHT CONTROL SYSTEMS
The flight control systems in most general aviation airplanes consist of the cockpit controls, cables, pulleys, and linkages
connected to the movable control surfaces outside the airplane.
 There are three primary and two secondary flight control systems. The primary flight control systems consist of the
elevator, aileron, and rudder, which are essential in controlling the aircraft. The secondary control systems consist of the
trim tabs and wing flaps. The trim tabs enable the pilot to trim out control pressures, and the flaps enable the pilot to
change the lifting characteristics of the wing and also to decrease the speed at which the wing stalls. All of the flight
control systems, except the wing flaps, were discussed in Chapter 1, Principles of Flight. The flaps will be discussed at
this point.
Wing Flaps
Wing flaps are a movable part of the wing, normally hinged to the inboard trailing edge of each wing. Flaps are extended
or retracted by the pilot. Extending the flaps increases the wing camber, wing area (some types), and the angle of attack
of the wing. This increases wing lift and also increases induced drag. The increased lift enables the pilot to make steeper
approaches to a landing without an increase in airspeed. Their use at recommended settings also provides increased lift
under certain takeoff conditions. When the flaps are no longer needed, they can be retracted.
Pilots are cautioned to operate the flaps within the airspeed limitations set forth for the particular airplane being
flown. If the speed limitations are exceeded, the increased drag forces created by extending the flaps could result in
structural damage to the airplane.
Figure 2-1 shows the four types of flaps in general use. The plain or simple flap is a portion of the trailing edge of
the wing on a hinged pivot which allows the flap to be moved downward, thereby changing the chord line, angle of
attack, and the camber of the wing. The split flap is a hinged portion of the bottom surface of the wing only, which
when extended increases the angle of attack by changing the chord line. The Fowler flap, when extended, not only
tilts downward but also slides rearward on tracks. This increases angle of attack, wing camber, and wing area,
thereby providing added lift without significantly increasing drag. The slotted flap in addition to changing the
wing’s camber and chord line also lets a portion of high pressure air beneath the wing travel through a slot. This
increases the velocity of air and increases lift.
With all four types of flaps, the practical effect of the flap is to permit a steeper angle of descent without an
increase in airspeed. Extended flaps also permit a slower speed to be used on an approach and landing, thus
reducing the distance of the landing roll.
Landing Gear
The landing gear system supports the airplane during the takeoff run, landing, taxiing, and when parked. These
ground operations require that the landing gear be capable of steering, braking, and absorbing shock.
A steerable nose gear or tailwheel permits the airplane to be controlled by the pilot throughout all operations while
on the ground. Individual brakes installed on each main wheel permit the pilot to use either brake individually as an
aid to steering or, by applying both brakes simultaneously, the pilot can decelerate or stop the airplane. Hydraulic
shock struts or leaf springs are installed in the various types of landing gear systems to absorb the impact of
landings, or the shock of taxiing over rough ground.
There are two basic types of landing gear used on light airplanes. These are:
•Conventional Landing Gear
•Tricycle Landing Gear
Conventional Landing Gear
The conventional landing gear, which was used on most airplanes manufactured years ago, is still used on some
airplanes designed for operations on rough fields. This landing gear system consists of two main wheels and a tailwheel.
Shock absorption is usually provided on the main landing gear by inflated tires and shock absorbers while it is provided
on the tailwheel by a spring assembly to which the tailwheel is bolted. The tailwheel is usually steerable by the rudder
pedals through at least 15° on each side of a center point beyond which it becomes full swiveling.
Tricycle Landing Gear
The tricycle landing gear is used on most airplanes produced today. This gear has advantages over the conventional gear
because it provides easier ground handling characteristics. The main landing gear is constructed similar to the main
landing gear on the conventional system, but is located further rearward on the airplane. The nose gear is usually
steerable by the rudder pedals. Some airplanes are equipped with a retractable landing gear. Retracting the gear reduces
the drag, and increases the airspeed without
additional power.
The landing gear normally retracts into the wing or fuselage through an opening which is covered by doors after the
gear is retracted. This provides for the unrestricted flow of air across the opening which houses the gear. The retraction
or extension of the landing gear is accomplished either electrically or hydraulically by landing gear controls from
within the cockpit. Indicators are provided in the cockpit to indicate whether the wheels are extended and locked, or
retracted. In retractable landing gear installations, a system is provided for emergency gear extension in the event the
normal landing gear mechanism fails to lower the gear. ELECTRICAL SYSTEM
Electrical energy is required to operate navigation and communication radios, lights, and other airplane equipment.
Many airplanes in the past were not equipped with an electrical system. They were equipped with a magneto system
which supplied electrical energy to the engine ignition system only. Modern airplanes still use an independent magneto
system, but in addition are equipped with an electrical system. The magneto system does not depend upon the airplane
electrical system for operation. In other words, the airplane electrical system can be turned off in flight and the engine
will continue to operate efficiently, utilizing the electrical energy provided by the magnetos.
Most airplanes are equipped with a 14- or 28-volt direct-current electrical system. The 28-volt system provides an
electrical reserve capacity for more complex systems, including additional electrical energy for starting.
A basic airplane electrical system consists of the following components: Alternator, Battery, Master or battery switch,
Alternator switch, Bus bar, fuses, and circuit breakers, Voltage regulator, Ammeter, Starting motor, Associated
electrical wiring, and Accessories
Engine-driven alternators or generators supply electric current to the electrical system and also maintain a sufficient
electrical charge in the battery which is used primarily for starting.
There are several basic differences between alternators and generators. Most generators will not produce a sufficient
amount of electrical current at low engine revolutions per minute (RPM) to operate the entire electrical system.
Therefore, during operations at low engine RPM’s, the electrical needs must be drawn from the battery, which in a
short time may be depleted.
An alternator, however, produces a sufficient amount of electrical current at slower engine speeds by first producing
alternating current which is converted to direct current. Another advantage is that the electrical output of an alternator
is more constant throughout the ranges of engine speeds. Alternators are also lighter in weight, less expensive to
maintain, and less prone to become overloaded during conditions of heavy electrical loads.
Electrical energy stored in a battery provides a source of electricity for starting the engine and a limited supply of
electricity for use in the event the alternator fails.
Some airplanes are equipped with receptacles to which external auxiliary power units (APU) can be connected to
provide electrical energy for starting. These are very useful, especially during cold weather starting. Care must be
exercised in starting engines using an APU.
A master switch is installed on airplanes to provide a means for the pilot to turn the electrical system “on” and “off.”
Turning the master switch “on” provides electrical energy to all the electrical equipment circuits with the exception
of the ignition system. Although additional electrical equipment may be found in some airplanes, the following lists
the equipment most commonly found which uses the electrical system for its source of energy:
- External lights •Stall warning system
- Interior cabin lights •Instrument lights
- Radio equipment •Selected flight instruments
- Fuel gauges •Pitot heat Electric fuel pump
Some airplanes are equipped with a battery switch which controls the electrical power to the airplane in a manner similar
to the master switch. In addition, an alternator switch is installed which permits the pilot to exclude the alternator from
the electrical system in the event of alternator failure. With the alternator switch “off,” the entire electrical load is placed
on the battery. Therefore, all nonessential electrical equipment should be turned off to conserve the energy stored in the
battery.
A bus bar is used as a terminal in the airplane electrical system to connect the main electrical system to the equipment
using electricity as a source of power. This simplifies the wiring system and provides a common point from which
voltage can be distributed throughout the system. [See Figure 2-2]
Fuses or circuit breakers are used in the electrical system to protect the circuits and equipment from electrical overload.
Spare fuses of the proper amperage limit should be carried in the airplane to replace defective or blown fuses. Circuit
breakers have the same function as a fuse but can be manually reset, rather than replaced, if an overload condition
occurs in the electrical system. Placards at the fuse or circuit breaker location identify the circuit by name and show the
amperage limit. [See Figure 2-3]
An ammeter is an instrument used to monitor the performance of the airplane electrical system. Not all airplanes are
equipped with an ammeter. Some are equipped with a light which, when lighted, indicates a discharge in the system as a
generator/alternator malfunction.
An ammeter shows if the alternator/generator is producing an adequate supply of electrical power to the system by
measuring the amperes of electricity. This instrument also indicates whether the battery is receiving an electrical charge.
The face of some ammeters is designed with a zero point in the upper center of the dial and a plus value to the right of
center; a negative value is to the left. A vertical needle swings to the right or left, depending upon the performance of the
electrical system. If the needle indicates a plus value, it means that the battery is being charged. After power is drawn
from the battery for starting, the needle will indicate a noticeable plus charge value for a short period of time, and then
stabilize to a lower plus charge value. [See Figure 2-4]
If the needle indicates a minus value, it means that the generator or alternator output is inadequate and energy is being
drawn from the battery to supply the system. This could be caused by either a defective alternator/generator or by an
overload in the system, or both. Full scale ammeter discharge or rapid fluctuation of the needle usually means
generator/alternator malfunction. If this occurs, the pilot should cut the generator/alternator out of the system and
conserve battery power by reducing the load on the electrical system. The loadmeter type of ammeter shows the load
being placed on the alternator. [Figure 2-4]
A voltage regulator controls the rate of charge to the battery by stabilizing the generator or alternator electrical output.
The generator/alternator voltage output is usually slightly higher than the battery voltage. For example, a 12-volt
battery would be fed by a generator/alternator system of approximately 14 volts. The difference in voltage keeps the
battery charged.
ENGINE OPERATION
Knowledge of a few general principles of engine operation will help the pilot obtain increased dependability and
efficiency from the engine and, in many instances, this knowledge will help in avoiding engine failure.
In this short chapter, it is impractical to discuss in detail the various types of engines and the finer points of operation
which can be learned only through experience. Information from the manufacturer’s instruction manual; familiarity
with the operating limitations for the airplane engine; and specific advice from a flight instructor, combined with the
information contained within this section, should provide adequate information to operate an airplane engine
satisfactorily.
How an Engine Operates
Most light airplane engines are internal combustion of the reciprocating type which operate on the same principle as
automobile engines. They are called reciprocating engines because certain parts move back and forth in contrast to a
circular motion such as a turbine. Some smaller airplanes are equipped with turbine engines, but this type will not be
discussed in this handbook. As shown in figure 2-5, the reciprocating engine consists of cylinders, pistons, connecting
rods, and a crankshaft. One end of a connecting rod is attached to a piston and the other end to the crankshaft.
This connecting rod converts the straight-line motion of the piston to the rotary motion of the crankshaft, which turns
the propeller. At the closed end of the cylinder, there are normally two spark plugs which ignite the fuel, and two
openings over which valves open and close. One valve (the intake valve) when open admits the mixture of fuel and air,
and the other (the exhaust valve) when open permits the burned gases to escape. For the engine to complete one cycle,
the piston must complete four strokes. This requires two revolutions of the crankshaft. The four strokes are the intake,
compression, power, and exhaust. The following describes one cycle of engine
operation.
From this description, notice that each cylinder of the engine delivers power only once in every four strokes of the
piston or every two revolutions of the crankshaft. The momentum of the crankshaft carries the piston through the other
three strokes although the diagram shows the action of only one cylinder. To increase power and gain smoothness of
operation, other cylinders are added and the power strokes are timed to occur at successive intervals during the revolution
of the crankshaft.
Aircraft engines are classified by the various ways the cylinders are arranged around the central crankcase. Most general
aviation airplane engines are classed as the horizontally opposed, which have the cylinder banks arranged in two rows,
directly opposite to each other and using the same crankshaft.
Larger and more powerful reciprocating engines are classed as radial engines. In these engines, the cylinders are placed
in a circular pattern around the crankcase, which is placed in the center of the circle.
Other engine classifications are the in-line engine with the cylinders placed in one straight row, and the “vee” type
with the cylinders placed in two rows forming a “V” such as the V-8 and V-12 layouts.
Cooling System
The burning fuel within the cylinders produces intense heat, most of which is expelled through the exhaust. Much of
the remaining heat, however, must be removed to prevent the engine from overheating. In practically all automobile
engines, excess heat is carried away by a coolant circulating around the cylinder walls.
Most light airplane engines are air cooled. The cooling process is accomplished by cool air being forced into the
engine compartment through openings in front of the engine cowl. This ram air is routed by baffles over fins attached
to the engine cylinders, and other parts of the engine, where the air absorbs the engine heat. Expulsion of the hot air
takes place through one or two openings at the rear bottom of the engine cowling.
Some airplanes are equipped with a device known as cowl flaps which are used to control engine temperatures during
various flight operations. Cowl flaps are hinged covers which fit over the opening through which the hot air is
expelled. By adjusting the cowl flap opening, the pilot can regulate the engine temperature during flight. If the engine
temperature is low, the cowl flaps can be closed, thereby restricting the flow of expelled hot air and increasing engine
temperature. If the engine temperature is high, the cowl flaps can be opened to permit a greater flow of air through the
system, thereby decreasing the engine temperature. Usually during low airspeed and high power operations such as
takeoffs and climbs, the cowl flaps are opened. During higher speed and lower power operations such as cruising
flight and descents, the cowl flaps are closed.
Under normal operating conditions in airplanes not equipped with cowl flaps, the engine temperature can be
controlled by changing the airspeed or the power output of the engine. High engine temperatures can be decreased by
increasing the airspeed and/or reducing the power.
The oil temperature gauge indicates the temperature of the oil which is heated by the engine; therefore, this gauge
gives an indirect and delayed indication of rising engine temperature. However, the oil temperature gauge should be
used for determining engine temperature if this is the only means available.
Many airplanes are equipped with a cylinder-head temperature gauge. This is an additional instrument which will
indicate a direct and immediate cylinder temperature change. This instrument is calibrated in degrees Celsius or
Fahrenheit, and is usually color coded with a green arc to indicate the normal operating range. A red line on the
instrument indicates maximum allowable cylinder head temperature.
To avoid excessive cylinder head temperatures, a pilot can open the cowl flaps, increase airspeed, enrich the mixture,
or reduce power. Any of these procedures will aid in reducing the engine temperature.
When an airplane engine is operated on the ground, very little air flows past the cylinders (particularly if the engine is
closely cowled) and overheating is likely to occur. Overheating may also occur during a prolonged climb, because the
engine at this time is usually developing high power at relatively slow airspeed.
Operating the engine at higher than its designed temperature can cause loss of power, excessive oil consumption, and
detonation. It will also lead to serious permanent damage, such as, scoring the cylinder walls, damaging the pistons
and rings, and burning and warping the valves. To aid the pilot in avoiding excessive temperatures, engine
temperature instruments in the cockpit should be monitored in flight. Ignition System
The function of the ignition system is to provide a spark to ignite the fuel/air mixture in the cylinder. The magneto
ignition system is used on most aircraft engines because it does not depend on an external source of energy such as
the electrical system. Magnetos are self-contained engine driven units supplying ignition current. However, the
magneto must be actuated by rotating the engine before
current is supplied to the ignition system. The aircraft battery furnishes electrical power to operate the starter system; the
starter system actuates the rotating element of the magneto; and the magneto then furnishes the spark to each cylinder to
ignite the fuel/air mixture. After the engine starts, the starter system is disengaged, and the battery no longer has any
part in the actual operation of the engine. If the battery (or master) switch is turned “OFF,” the engine will continue to
run. However, this should not be done since battery power is necessary at low engine RPM to operate other electrical
equipment (radio, lights, etc.). When the generator or alternator is operating, the battery will be charging.
Most aircraft engines are equipped with a dual ignition system; that is, two magnetos to supply the electrical current to
two spark plugs for each combustion chamber. One magneto system supplies the current to one set of plugs; the second
magneto system supplies the current to the other set of plugs. This is the reason that the ignition switch has four
positions: “OFF,” “LEFT,” “RIGHT,” and “BOTH.” With the switch in the “L” or “R” position, only one magneto is
supplying current and only one set of spark plugs is firing. With the switch in the “BOTH” position, both magnetos are
supplying current and both sets of spark plugs are firing. The main advantages of the dual system are: increased safety,
in case one magneto system fails, the engine may be operated on the other system until a landing can be made; and
improved burning and combustion of the mixture, and consequently improved performance.
NOTE: To ensure that both ignition systems are operating properly, each system is checked during the engine runup prior
to flight. This check should be accomplished in accordance with the manufacturer’s recommendations in the Aircraft
Flight Manual or Pilot’s Operating Handbook.
It is important to turn the ignition switch to “BOTH” for flight and completely “OFF” when shutting down the engine
after flight. Even with the electrical master switch “OFF” and the ignition switch on either “BOTH” or “LEFT” or
“RIGHT” magnetos, the engine could fire if the propeller is moved from outside the airplane. Also, if the magneto
switch ground wire is disconnected or broken, the magneto is “ON” even though the ignition switch is in the “OFF”
position.
Fuel System
The function of the fuel system is to provide a means of storing fuel in the airplane and transferring this fuel to the
airplane engine. Fuel systems are classified according to the method used to furnish fuel to the engine from the fuel
tanks. The two classifications are the “gravity feed” and the “fuel pump system.”
The gravity feed system utilizes the force of gravity to transfer the fuel from the tanks to the engine. This system can be
used on high wing airplanes if the fuel tanks are installed in the wings. This places the fuel tanks above the carburetor
and the fuel is gravity fed through the system and into the carburetor.
If the design of the airplane is such that gravity cannot be used to transfer fuel, fuel pumps are installed. This is true on
low-wing airplanes where the fuel tanks in the wings are located below the carburetor.
Two fuel pump systems are used on most airplanes. The main pump system is engine driven and an auxiliary electric
driven pump is provided for use in the event the engine pump fails. The auxiliary pump, commonly know as the “boost
 pump,” provides added reliability to the fuel system, and is also used as an aid in engine starting. The electric auxiliary
pump is controlled by a switch in the cockpit.
Because of variation in fuel system operating procedures, the pilot should consult the Aircraft Flight Manual or Pilot’s
Operating Handbook for specific operating procedures.
Fuel Tanks, Selectors, Strainers, and Drains
Most airplanes are designed to use space in the wings to mount fuel tanks. All tanks have filler openings which are
covered by a cap. This system also includes lines connecting to the engine, a fuel gauge, strainers, and vents which
permit air to replace the fuel consumed during flight. Fuel overflow vents are provided to discharge fuel in the event the
fuel expands because of high temperatures. Fuel tank sump drains are located at the bottom of the tanks from which
water and other sediment can be drained from the tanks. Fuel lines pass through a selector assembly located in the
cockpit which provides a means for the pilot to turn the fuel “off,” “on,” or to select a particular tank from which to draw
fuel. The fuel selector assembly may be a simple “on/off” valve, or a more complex arrangement which permits the pilot
to select individual tanks or use all tanks at the same time.
Airplanes are equipped with fuel strainers, called sumps, located at the low point in the fuel lines between the fuel
selector and the carburetor. The strainer filters the fuel and traps water and sediment in a container which can be drained
to remove foreign matter from the fuel.
Fuel Primer
A manual fuel primer is installed in some airplanes to aid in starting the engine, particularly when the weather is cold.
Activating the primer draws fuel from the tanks and vaporizes the fuel directly into the cylinders through small fuel
lines. When engines are cold and do not generate sufficient heat to vaporize the fuel, the primer is used not only to start
the engine, but to keep the engine running until sufficient engine heat is generated to keep the fuel constantly vaporized.
Fuel Pressure Gauge
If a fuel pump is installed in the fuel system, a fuel pressure gauge is also included. This gauge indicates the pressure in
the fuel lines. The normal operating pressure can be found in the Airplane Flight Manual or on the gauge by color
coding.
Induction, Carburetion, and Injection Systems
In reciprocating aircraft engines, the function of the induction system is to complete the process of taking in outside air,
mixing it with fuel, and delivering this mixture to the cylinders. The system includes the air scoops and ducts, the
carburetor or fuel injection system, the intake manifold, and (if installed) the turbo or superchargers.
Two types of induction systems are commonly used in light airplane engines: (1) carburetor system, which mixes the fuel
and air in the carburetor before this mixture enters the intake manifold, and (2) fuel injection system in which the fuel
and air are mixed just prior to entering each cylinder. The fuel injection system does not utilize a carburetor.
Carburetor System
The carburetor system uses one of two types of carburetor: (1) the float-type carburetor, which is generally installed in
airplanes equipped with small horsepower engines, and (2) the pressure type, used in higher horsepower engines. The
pressure type will not be discussed in this handbook, but many aspects of each are similar.
In the operation of the carburetor system, the outside air first flows through an air filter, usually located at an air intake
in the front part of the engine cowling. This filtered air flows into the carburetor and through a venturi, a narrow throat in
the carburetor. When the air flows through the venturi, a low pressure area is created, which forces the fuel to flow
through a main fuel jet located at the throat and into the airstream where it is mixed with the flowing air. [See Figure 2-7]
The fuel/air mixture is then drawn through the intake manifold and into the combustion chambers where it is ignited. The
“float-type carburetor” acquires its name from a float which rests on fuel within the float chamber. A needle attached to
the float opens and closes an opening in the fuel line. This meters the correct amount of fuel into the carburetor,
depending upon the position of the float, which is controlled by the level of fuel in the float chamber. When the level of
the fuel forces the float to rise, the needle closes the fuel opening and shuts off the fuel flow to the carburetor. It opens
when the engine requires additional fuel
Indications of Carburetor Icing
For airplanes with fixed-pitch propellers, the first indication of carburetor icing is loss of RPM. For airplanes with
controllable-pitch (constant-speed) propellers, the first indication is usually a drop in manifold pressure. In both cases, a
roughness in engine operation may develop later. There will be no reduction in RPM in airplanes with constant-speed
propellers, since propeller pitch is automatically adjusted to compensate for the loss of power, thus maintaining constant
RPM.
Use of Carburetor Heat
The carburetor heater is an anti-icing device that preheats the air before it reaches the carburetor. This preheating can be
used to melt any ice or snow entering the intake, to melt ice that forms in the carburetor passages (provided the
accumulation is not too great), and to keep the fuel mixture above the freezing temperature to prevent formation of
carburetor ice.
 When conditions are conducive to carburetor icing during flight, periodic checks should be made to detect its presence.
If detected, full carburetor heat should be applied immediately, and it should be left in the “on” position until the pilot is
certain that all the ice has been removed. If ice is present, applying partial heat or leaving heat on for an insufficient time
might aggravate the situation.
When heat is first applied, there will be a drop in RPM in airplanes equipped with fixed-pitch propellers; there will be a
drop in manifold pressure in airplanes equipped with controllable-pitch propellers. If no carburetor ice is present, there
will be no further change in RPM or manifold pressure until the carburetor heat is turned off; then the RPM or manifold
pressure will return to the original reading before heat was applied. If carburetor ice is present, there will normally be a
rise in RPM or manifold pressure after the initial drop (often accompanied by intermittent engine roughness); and then,
when the carburetor heat is turned “off,” the RPM or manifold pressure will rise to a setting greater than that before
application of the heat. The engine should also run more smoothly after the ice has been removed.
Whenever the throttle is closed during flight, the engine cools rapidly and vaporization of the fuel is less complete than
if the engine is warm. Also, in this condition, the engine is more susceptible to carburetor icing. Therefore, if the pilot
suspects carburetor-icing conditions and anticipates closed-throttle operation, the carburetor heat should be turned to
“full-on” before closing the throttle, and left on during the closed-throttle operation. The heat will aid in vaporizing the
fuel and preventing carburetor ice. Periodically, however, the throttle should be opened smoothly for a few seconds to
keep the engine warm, otherwise the carburetor heater may not provide enough heat to prevent icing.
Use of carburetor heat tends to reduce the output of the engine and also to increase the operating temperature.
Therefore, the heat should not be used when full power is required (as during takeoff) or during normal engine operation
except to check for the presence or removal of carburetor ice. In extreme cases of carburetor icing, after the ice has been
removed, it may be necessary to apply just enough carburetor heat to prevent further ice formation. However, this must
be done with caution. Check the engine manufacturer’s recommendations for the correct use of carburetor heat.
The carburetor heat should be checked during the engine runup. To properly perform this inspection, the manufacturer’s
recommendations should be followed.
Carburetor Air Temperature Gauge
Some airplanes are equipped with a carburetor air temperature gauge which is useful in detecting potential icing
conditions. Usually, the face of the gauge is calibrated in degrees Celsius (C), with a yellow arc indicating the carburetor
air temperatures at which icing may occur. This yellow arc ranges between -15° C and +5° C. If the air temperature and
moisture content of the air are such that the
carburetor icing is improbable, the engine can be operated with the indicator in the yellow range with no adverse
effects. However, if the atmospheric conditions are conducive to carburetor icing, the indicator must be kept outside
the yellow arc by application of carburetor heat.
Certain carburetor air temperature gauges have a red radial which indicates the maximum permissible carburetor inlet
air temperature recommended by the engine manufacturer; also, a green arc which indicates the normal operating
range.
Outside Air Temperature Gauge
Most airplanes are equipped with an outside air temperature gauge (OAT) calibrated in both degrees Celsius and
Fahrenheit. It is used not only for obtaining the outside or ambient air temperature for calculating true airspeed, but
also is useful in detecting potential icing conditions.
Fuel Injection System
Fuel injection systems have replaced carburetors on some engines. In this system, the fuel is normally injected either
directly into the cylinders or just ahead of the intake valve. The fuel injection system is generally considered to be less
susceptible to icing than the carburetor system. Impact icing of the air intake, however, is a possibility in either system.
Impact icing occurs when ice forms on the exterior of the airplane and results in clogging openings such as the air intake
for the injection system.
There are several types of fuel injection systems in use today. Although there are variations in design, the operational
methods of each are generally similar. Most designs include an engine-driven fuel pump, a fuel/air control unit, fuel
distributor, and discharge nozzles for each cylinder.
Some of the advantages of fuel injection are:
•Reduction in evaporative icing. •Precise control of mixture.
•Better fuel flow. •Better fuel distribution.
•Faster throttle response. •Easier cold weather starts.
Disadvantages of fuel injected aircraft are:
•Difficulty in starting a hot engine.
•Vapor locks during ground operations on hot days.
•Problems associated with restarting an engine that quits because of fuel starvation.
Fuel injected aircraft can be difficult for the the new pilot mainly because fuel-injected airplanes (unlike modern cars)
don’t have computers to help with managing fuel flow.
The air intake for the fuel injection system is somewhat similar to that used in the carburetor system. The fuel injection
system, however, is equipped with an alternate air source located within the engine cowling. This source is used if the
external air source is obstructed by ice or by other matter. The alternate air source is usually operated automatically with
a backup manual system that can be used if the automatic feature malfunctions.
Fuel injected engines are not subject to refrigeration icing at the venturi like carburetor-equipped engines, but they are
subject to impact icing at the air filter and intake ducting.
Proper Fuel is Essential
There are several grades of aviation fuel available; therefore, care must be exercised to assure that the correct aviation
grade is being used for the specific type of engine. It can be harmful to the engine and dangerous to the flight if the
wrong kind of fuel is used. It is the pilot’s responsibility to obtain the proper grade of fuel. The proper grade is stated in
the Aircraft Flight Manual or Pilot’s Operating Handbook, on placards in the cockpit, and next to the filler caps.
The proper fuel for an engine will burn smoothly from the spark plug outward, exerting a smooth pressure downward on
the piston. Using low-grade fuel or too lean a mixture can cause detonation. Detonation or knock is a sudden explosion
or shock, to a small area of the piston top, similar to striking it with a hammer. Detonation produces extreme heat which
often progresses into preignition, causing structural stresses on parts of the engine. Therefore, to prevent detonation, the
pilot should use the proper grade of fuel, maintain a sufficiently rich mixture, and maintain engine temperatures within
the recommended limits. [Figure 2-9]
Aviation gasolines are identified by octane or performance numbers (grades) which designate the antiknock value or
knock resistance of the fuel mixture in the engine cylinder. The higher the grade of gasoline, the more pressure the
fuel can withstand without detonating.
Airplane engines are designed to operate using a specific grade of fuel as recommended by the manufacturer. Lower
numbered octane fuel is used in lower compression engines because these fuels ignite at a lower temperature. Higher
octane fuels are used in higher compression engines because they must ignite at higher temperatures but not
prematurely. If the proper grade of fuel is not available, it is possible, but not desirable, to use the next higher grade as
a substitute. The terms “octane” and “grade” are often used interchangeably, but the term “grade” is technically more
accurate since the octane value is a percentile, and doesn’t go over 100. Dyes are added to aviation fuels to assist in
identification of the proper fuel grade.
GRADE COLOR
80 RED
100 GREEN
100LL BLUE
TURBINE COLORLESS
It should be noted that if fuel grades are mixed together they will become clear or colorless.
Fuel Contamination
Water and dirt in fuel systems are dangerous; the pilot must either eliminate or prevent contamination. Of the accidents
attributed to powerplant failure from fuel contamination, most have been traced to:
- Inadequate preflight inspection by the pilot.
- Servicing of aircraft with improperly filtered fuel from small tanks or drums.
- Storing aircraft with partially filled fuel tanks.
- Lack of proper maintenance.
To help alleviate these problems, fuel should be drained from the fuel strainer quick drain and from each fuel tank sump
into a transparent container and be checked for dirt and water. Experiments have shown that when the fuel strainer is
being drained, water in the tank may not appear until all the fuel has been drained from the lines leading to the tank. This
indicates that the water remains in the tank and is not forcing the fuel out of the fuel lines leading to the fuel strainer.
Therefore, drain enough fuel from the fuel strainer to be certain that fuel is being drained from the tank. The amount will
depend on the length of fuel line from the tank to the drain. If water is found in the first sample, drain further samples
until no trace appears.
Experiments have also shown that water will still remain in the fuel tanks after the drainage from the fuel strainer had
ceased to show any trace of water. This residual water can be removed only by draining the fuel tank sump drains.
The pilot should be able to identify suspended water droplets in the fuel from a cloudy appearance of the fuel; or the
clear separation of water from the colored fuel which occurs after the water has settled to the bottom of the tank. Water is
the principal contaminant of fuel, and to increase flight safety, the fuel sumps should be drained during preflight.
In addition to the above measures, the following should be considered. The fuel tanks should be filled after each flight,
or at least after the last flight of the day. This will prevent moisture condensation within the tank since no air space will
be left. If the pilot chooses to refuel with only the amount that can be carried on the next flight—perhaps a day
later—there is an added risk of fuel contamination by moisture condensation within the tank. Each additional day may
add to the amount of moisture condensation within the tank or tanks. Another preventive measure the pilot can take is to
avoid refueling from cans and drums. This practice introduces a major likelihood of fuel contamination.
As has been pointed out, the practice of using a funnel and chamois skin when refueling from cans or drums is hazardous
under any condition, and should be discouraged. It is recognized, of course, that in remote areas or in emergency
situations, there may be no alternative to refueling from sources with inadequate anti contamination systems, and a
chamois skin and funnel may be the only possible means of filtering fuel.
In addition, it should be clearly understood that the use of a chamois will not always assure decontaminated fuel. Worn
out chamois will not filter water; neither will a new, clean chamois that is already water-wet or damp. Most imitation
chamois skins will not filter water. There are many filters available that are more effective than the old chamois and
funnel system.
Refueling Procedures
Static electricity, formed by the friction of air passing over the surfaces of an airplane in flight and by the flow of fuel
through the hose and nozzle, creates a fire hazard during refueling. To guard against the possibility of a spark igniting
fuel fumes, a ground wire should be attached to the aircraft before the cap is removed from the tank. The refueling
nozzle should be grounded to the aircraft before refueling is begun and throughout the refueling process. The fuel truck
should also be grounded to the aircraft and the ground. If fueling from drums or cans is necessary, proper bonding and
grounding connections are extremely important, since there is an ever present danger of static discharge and fuel vapor
explosion. Nylon, dacron, or wool clothing are especially prone to accumulate and discharge static electricity from the
person to the funnel or nozzle. Drums should be placed near grounding posts and the following sequence of connections
observed: Drum to ground, Ground to aircraft, Drum to aircraft, Nozzle to aircraft before the aircraft tank cover is
opened.
•When disconnecting, reverse the order.
The passage of fuel through a chamois increases the charge of static electricity and the danger of sparks. The aircraft
must be properly grounded and the nozzle, chamois filter, and funnel bonded to the aircraft. If a can is used, it should be
connected to either the grounding post or the funnel. Under no circumstances should a plastic bucket or similar
nonconductive container be used in this operation. This is a surprisingly common cause of aircraft fires.
Oil System
Proper lubrication of the engine is essential to the extension of engine life and prevention of excessive maintenance. The
oil system provides a means of storing and circulating oil throughout the internal components of a reciprocating engine.
Lubricating oil serves two purposes: (1) it furnishes a coating of oil over the surfaces of the moving parts, preventing
direct metal-to metal contact and the generation of heat, and (2) it absorbs and dissipates, through the oil cooling system,
part of the engine heat produced by the internal combustion process.
Usually the engine oil is stored in a sump at the bottom of the engine crankcase. An opening to the oil sump is provided
through which oil can be added and a dipstick is provided to measure the oil level in the sump.
A pump forces oil from the sump to the various parts of the engine that require lubrication. The oil then drains back to
the sump for recirculation.
Each engine is equipped with an oil pressure gauge and an oil temperature gauge which are monitored to determine that
the oil system is functioning properly.
Oil pressure gauges indicate pounds of pressure per square inch (PSI), and are color coded with a green arc to indicate
the normal operating range. Also, at each end of the arc, some gauges have a red line to indicate high
oil pressure, and another red line to indicate low oil pressure.
The oil pressure indication varies with the temperature of the oil. If the oil temperature is cold, the pressure will be
higher than if the oil is hot.
A loss of oil pressure is usually followed by engine failure. If this occurs while on the ground, the pilot must shut the
engine down immediately; if in the air, land at a suitable emergency landing site.
The oil temperature gauge is calibrated in either Celsius or Fahrenheit and color coded in green to indicate the normal
temperature operating range.
It is important that the pilot check the oil level before each flight. Starting a flight with an insufficient oil supply can lead
to serious consequences. The airplane engine will burn off a certain amount of oil during operation, and beginning a
flight when the oil level is low will usually result in an insufficient supply of oil before the flight terminates.
There are many different types of oil manufactured for aviation use. The engine manufacturer’s recommendation should
be followed to determine the type and weight of oil to use. This information can be found in the Aircraft Flight Manual
or Pilot’s Operating Handbook, or on placards on or near the oil filler cap.
PROPELLER
A propeller is a rotating airfoil, and is subject to induced drag, stalls, and other aerodynamic principles that apply to any
airfoil. It provides the necessary thrust to pull, or in some cases push, the airplane through the air. This is accomplished
by using engine power to rotate the propeller which in turn generates thrust in much the same way as a wing produces
lift. The propeller has an angle of attack which is the angle between the chord line of the propeller’s airfoil and its
relative wind (airflow opposite to the motion of the blade). A propeller blade is twisted. The blade angle changes from the
hub to the tip with the greatest angle of incidence, or highest pitch, at the hub and the smallest at the tip. [Figure 2-10]
The reason for the twist is to produce uniform lift from the hub to the tip. As the blade rotates, there is a difference in the
actual speed of the various portions of the blade. The tip of the blade travels faster than that part near the hub because the
tip travels a greater distance than the hub in the same length of time. Changing the angle of incidence (pitch) from the
hub to the tip to correspond with the speed produces uniform lift throughout the length of the blade. If the propeller blade
was designed with the same angle of incidence throughout its entire length, it would be extremely inefficient because as
airspeed increases in flight, the portion near the hub would have a negative angle of attack while the blade tip would be
stalled. [Figure 2-11]
Figure 2-11.—Relationship of travel distance and speed of various portions of propeller blade.
Geometric pitch is the distance in inches that the propeller would move forward in one revolution if it were rotated in a
solid medium so as not to be affected by slippage as it is in the air. Effective pitch is the actual distance it moves
forward through the air in one revolution. Propeller slip is the difference between the geometric pitch and effective
pitch. Pitch is proportional to the blade angle which is the angle between the chord line of the blade and the
propeller’s plane of rotation. [See Figure 2-12]
Small airplanes are equipped with either one of two types of propellers. One is the fixed-pitch, and the other is the
controllable-pitch or constant-speed propeller.
Fixed-Pitch Propeller
The pitch of this propeller is fixed by the manufacturer and cannot be changed by the pilot. There are two types of
fixed-pitch propellers; the climb propeller and the cruise propeller. Whether the airplane has a climb or cruise
propeller installed depends upon its intended use. The climb propeller has a lower pitch, therefore less drag. This
results in the capability of higher RPM and more horsepower being developed by the engine. This increases
performance during takeoffs and climbs, but decreases performance during cruising flight.
The cruise propeller has a higher pitch, therefore more drag. This results in lower RPM and less horsepower
capability. This decreases performance during takeoffs and climbs, but increases efficiency during cruising flight.
The propeller on a low-horsepower engine is usually mounted on a shaft which may be an extension of the engine
crankshaft. In this case, the RPM of the propeller would be the same as the engine RPM.
On higher horsepower engines, the propeller is mounted on a shaft geared to the engine crankshaft. In this type, the
RPM of the propeller is different than that of the engine.
If the propeller is a fixed-pitch and the speed of the engine and propeller is the same, a tachometer is the only indicator
of engine power.
A tachometer is calibrated in hundreds of RPM, and gives a direct indication of the engine and propeller RPM. The
instrument is color coded with a green arc denoting the normal operating range and a red line denoting the maximum
continuous operating RPM. Some tachometers have additional marking or interrupted arcs. Therefore, the
manufacturer’s recommendations should be used as a reference to clarify any misunderstanding of tachometer
markings.
The revolutions per minute are regulated by the throttle which controls the fuel/air flow to the engine. At a given
altitude, the higher the tachometer reading the higher the power output of the engine.
There is a condition under which the tachometer does not show correct power output of the engine. This occurs when
operating altitude increases. For example, 2,300 RPM at 5,000 feet produce less horsepower than 2,300 RPM at sea
level. The reason for this is that air density decreases as altitude increases. Power output depends on air density,
therefore decreasing the density decreases the power output of the engine. As altitude changes, the position of the
throttle must be changed to maintain the same RPM. As altitude is increased, the throttle must be opened further to
indicate the same RPM as at a lower altitude. Controllable-Pitch Propellers
The pitch on these propellers can be changed in flight; therefore, they are referred to as controllable-pitch propellers.
These propeller systems vary from a simple two-position propeller to more complex automatic constant-speed
propellers.
The number of pitch positions at which the propeller can be set may be limited, such as a two-position propeller with
only high or low pitch available. Many other propellers, however, are variable pitch, and can be adjusted to any pitch
angle between a minimum and maximum pitch setting.
An airplane equipped with a controllable-pitch propeller has two controls: (1) a throttle control and (2) a propeller
control. The throttle controls the power output of the engine which is registered on the manifold pressure gauge. The
manifold pressure gauge is a simple barometer that measures the air pressure in the engine intake manifold in inches of
mercury. It is color coded with a green arc indicating the normal operating range.
The propeller control regulates the engine RPM and in turn the propeller RPM. The RPM is registered on the
tachometer. The pilot can set the throttle control and propeller control at any desired manifold pressure and RPM setting
within the engine operating limitation. Within a given power setting, when using a constant-speed propeller, the pilot can
set the propeller control to a given RPM and the propeller governor will automatically change the pitch (blade angle) to
counteract any tendency for the engine to vary from this RPM. For example, if manifold pressure or engine power is
increased, the propeller governor automatically increases the pitch of the blade (more propeller drag) to maintain the
same RPM.
A controllable-pitch propeller permits the pilot to select the blade angle that will result in the most efficient performance
for a particular flight condition. A low blade angle or decreased pitch, reduces the propeller drag and allows more engine
power for takeoffs. After airspeed is attained during cruising flight, the propeller blade is changed to a higher angle or
increased pitch.
Consequently, the blade takes a larger bite of air at a lower power setting, and therefore increases the efficiency of the
flight. This process is similar to shifting gears in an automobile from low gear to high gear. For any given RPM there
is a manifold pressure that should not be exceeded. If manifold pressure is excessive for a given RPM, the pressure
within the cylinders could be exceeded, thus placing undue stress on them. If repeated too frequently, this stress could
weaken the cylinder components and eventually cause engine failure.
The pilot can avoid conditions that would possibly overstress the cylinders by being constantly aware of the RPM,
especially when increasing the manifold pressure. Pilots should conform to the manufacturer’s recommendations for
power settings of a particular engine so as to maintain the proper relationship between manifold pressure and RPM.
Remember, the combination to avoid is a high throttle setting (manifold pressure indication) and a low RPM (tachometer
indication).
When both manifold pressure and RPM need to be changed, the pilot can further help avoid engine overstress by
making power adjustments in the proper order. When power settings are being decreased, reduce manifold pressure
before RPM. When power settings are being increased, reverse the order—increase RPM first, then manifold pressure. If
RPM is reduced before manifold pressure, manifold pressure will automatically increase and possibly exceed the
manufacturer’s tolerances.
Summarizing: In an airplane equipped with a controllable-pitch propeller, the throttle controls the manifold pressure and
the propeller control is used to regulate the RPM. Avoid high manifold pressure settings with low RPM. The preceding
is a standard procedure for most situations, but with unsupercharged engines it is sometimes modified to take advantage
of auxiliary fuel metering devices in the
carburetor. These devices function at full throttle settings, providing additional fuel flow. This additional fuel helps
cool the engine during takeoffs and full power climbs where engine overheating may be a problem. In such
instances, a small reduction in RPM is possible without overstressing the engine, even though the throttle is in the
full-power position. If in doubt, the manufacturer’s recommendations should be followed.
STARTING THE ENGINE
Before starting the engine, the airplane should be in an area where the propeller will not stir up gravel or dust that
could cause damage to the propeller or property. Rules of safety and courtesy should be strictly observed to avoid
personal injury or annoyance. The wheels should be chocked and the brakes set to avoid hazards caused by
unintentional movement. A frequent cause of ground accidents is the failure by pilots to make sure that the plane is
secured properly before starting the engine!
Engines Equipped with a Starter
The pilot should be familiar with the manufacturer’s recommended starting procedures for the airplane being flown.
This information can be found in the Airplane Flight Manual or Pilot’s Operating Handbook, or other sources. There are
not only different procedures applicable to starting engines equipped with conventional carburetors and those equipped
with fuel injection systems, but also between different systems of either carburetion or fuel injection. The pilot should
always ascertain that no one is near the propeller, call “clear prop,” and wait for a possible response before engaging the
propeller. Continuous cranking beyond 30 seconds’ duration may damage the starter. In addition, the starter motor
should be allowed to cool at least l to 2 minutes between cranking periods. If the engine refuses to start under normal
circumstances after a reasonable number of attempts, the possibility of problems with ignition or fuel flow should be
investigated. As soon as the engine starts, check for unintentional movement and set power to the recommended warmup
RPM. The oil pressure should then be checked to determine that the oil system is functioning properly. If the gauge does
not indicate oil pressure within 30 seconds, the engine should be stopped and a check should be made to determine what
is causing the lack of oil pressure. If oil is not circulating properly, the engine can be seriously damaged in a short time.
During cold weather there will be a much slower response in oil pressure indications than during warmer weather,
because colder temperatures cause the oil to congeal (thicken) to a greater extent. The engine must reach normal
operating temperature before it will run smoothly and dependably. Temperature is indicated by the cylinder-head
temperature gauge. If the airplane is not equipped with this gauge, the oil temperature gauge must be used. Remember, in
this case, that oil warms much slower in cold weather.
Before takeoff the pilot should perform all necessary checks for engine and airplane operation. Follow the
manufacturer’s recommendations when performing all checks. Always use a checklist; do not rely on memory.
Engines Not Equipped with a Starter
Because of the hazards involved in hand starting airplane engines, every precaution should be exercised. The safety
measures previously mentioned should be adhered to, and it is extremely important that a competent pilot be at the
controls in the cockpit. Also, the person turning the propeller should be thoroughly familiar with the technique. The
following are additional suggestions to aid in increasing the safety factor while hand starting airplanes.
The person who turns the propeller is in charge, and calls out the commands, “gas on, switch off, throttle closed, brakes
set.” The pilot in the cockpit will check these items and repeat the phrase to assure that there is no misunderstanding.
The person propping the airplane should push slightly on the airplane to assure that the brakes are set and are holding
firmly. The switch and throttle must not be touched again until the person swinging the prop calls “contact.” The pilot
will repeat “contact” and then turn on the switch in that sequence—never turn the switch on and then call “contact.”
For the person swinging the prop, a few simple precautions will help avoid accidents.
When touching a propeller, always assume that the switch is on, even though the pilot may confirm the statement
“switch off.” The switches on many engine installations operate on the principle of short circuiting the current. If the
switch is faulty, as sometimes happens, it can be in the “off” position and still permit the current to flow to the spark
plugs.
Be sure to stand on firm ground. Slippery grass, mud, grease, or loose gravel could cause a slip or fall into or under the
propeller. Never allow any portion of the body to get into the propeller arc of rotation. This applies even though the
engine is not being cranked; occasionally, a hot engine will backfire after shutdown when the propeller has almost
stopped rotating.
Stand close enough to the propeller to be able to step away as it is pulled down. Standing too far away from the
propeller requires leaning forward to reach it. This is an off-balance position and it is possible to fall into the blades as
the engine starts. Stepping away after cranking is also a safeguard in the event the brakes do not hold when the engine
starts.
When swinging the propeller, always move the blade downward by pushing with the palms of the hands. If the
blade is moved upward, or gripped tightly with the fingers and backfiring occurs, it could cause broken fingers or the
body to be pulled into the path of the propeller blades.
When removing the chocks from in front of the wheels, it should be remembered that the propeller, when revolving, is
almost invisible. There are cases every year where someone intending to remove the chocks walks directly into the
propeller. This happens with both landplanes and seaplanes. Pilots are urged to be extra vigilant when persons are
moving about an aircraft with the engine running.
Unsupervised “hand propping” of an airplane should not be attempted by inexperienced persons. Regardless of
the experience level, it should never be attempted by anyone without adhering to adequate safety measures.
Uninformed or inexperienced persons or nonpilot passengers should never handle the throttle, brakes, or switches
during starting procedures. The airplane should be securely
chocked or tied down, and great care should be exercised in setting the throttle. It may be well to turn the fuel
selector valve to the “off” position after properly priming the engine and prior to actually attempting the hand start.
After it starts, the engine will usually run long enough with the fuel “off” to permit walking around the propeller and
turning the fuel selector to the “on” position.
Idling the Engine During Flight
There could be potential problems created by excessive idling of the engine during flight, particularly for long
periods of time such as prolonged descents.
Whenever the throttle is closed during flight, the engine cools rapidly and vaporization of fuel is less complete. The
airflow through the carburetor system under such conditions may not be of sufficient volume to assure a uniform
mixture of fuel and air. Consequently, the engine may cease to operate because the mixture is too lean or too rich.
Suddenly opening or closing the throttle could aggravate this condition, and the engine may cough once or twice,
sputter, and stop.
Three precautions should be taken to prevent the engine from stopping while idling. First, make sure that the ground
idling speed is properly adjusted. Second, do not open or close the throttle abruptly. Third, keep the engine warm
during glides by frequently opening the throttle for a few seconds.
Exhaust Gas Temperature Gauge
Many airplanes are equipped with an exhaust gas temperature (EGT) gauge. If properly used, this engine instrument
can reduce fuel consumption by 10 percent because of its accuracy in indicating to the pilot the exact amount of fuel
that should be metered to the engine.
An EGT gauge measures, in degrees Celsius or Fahrenheit, the temperature of the exhaust gases at the exhaust
manifold. This temperature measurement varies with ratio of fuel to air entering the cylinders, and therefore can be
used as a basis for regulating the fuel/air mixture. This is possible because this instrument is very sensitive to
temperature changes.
Although the manufacturer’s recommendation for leaning the mixture should be adhered to, the usual procedure for
leaning the mixture on lower horsepower engines when an EGT is available is as follows: The mixture is leaned
slowly while observing the increase in exhaust gas temperature on the gauge. When the EGT reaches a peak, the
mixture should be enriched until the EGT gauge indicates a decrease in temperature. The number of degrees drop is
recommended by the engine manufacturer, usually approximately 25° to 75°. Engines equipped with carburetors will
run rough when leaned to the peak EGT reading, but will run smooth after the mixture is enriched slightly.
CHAPTER 3 - AIR LAW
Float planes should have life preservers. If you’re out of gliding range from shore, this becomes mandatory.
Single engine aircraft must carry a life raft if you are more than 100 NM or more than 30 minutes cruising speed from
the nearest emergency landing area. That life raft must be able to accommodate all persons. The same applies to a
multi-engine that can’t maintain flight with a failed engine. For a multi-engine that can
sustain flight with an engine out, those distances are doubled. For a single engine helicopter, the distance is 25 NM and
the time is 15 minutes. For a multi-engine helicopter, double those minimums.
If a helicopter is mandated to carry life rafts, then each passenger and crew also needs an immersion suit. The Pilot In
Command (PIC) needs to be wearing the immersion suit.
A flight plan or flight itinerary is required when a flight goes beyond 25 NM from the airport of departure. One of
these is also required for a flight to the US or to a military aerodrome.
An IFR flight usually needs a flight plan, but can be a flight itinerary if partly conducted outside of controlled airspace,
or if facilities are inadequate to permit the communication of a flight plan.
The Airspeed on a flight plan is True (TAS), not Indicated (IAS). If in knots, the format is N0123 for 123 knots. If in
Mach, the format is M082 for 0.82 Mach.
Cruising Level designations:
- Flight Level: FL085.
- Altitude: A075 (hundreds of feet).
- Uncontrolled VFR can just write VFR.
On an IFR flight plan, the total estimated elapsed time ends at the initial approach fix. On an IFR flight, having at least
one alternate airport is mandatory.
Fuel endurance time on a flight plan is given in hours and minutes, including all reserves.
If arriving at an airport controlled by a tower, the tower will close your flight plan automatically. However, it’s still a
good idea to call and make sure they closed it. In all other cases, you must close the flight plan yourself.
Minimum Altitudes and Distances:
- Built Up area, fixed wing: 1000’ above the highest obstacle within a horizontal radius of 2000’. - Built Up
area, rotary wing: 1000’ above the highest obstacle within a radius of 500’. - Non Built Up area: 500’ from
any person, vehicle, or structure.
- National Parks: At least 2000’ AGL.
UAV – Unmanned Aerial Vehicle (drone)
Drones are supposed to stay below 300’ AGL (in Canada), so it’s good if you’re always flying above 500’ AGL in a GA
aircraft. Drones also have to stay at least 8km from airports in Canada. But be aware that drone regulations are evolving
rapidly, so it’s best to check for up-to-date info on the Transport Canada website.
Landing Right-of-Way:
- Where an aircraft is in flight or maneuvering on the surface, the one that is landing or about to land has the right
of way.
- When two aircraft are both landing, the one at the lower altitude has the right of way.
If operating a float plane on water, you must obey both the rules for aircraft and for watercraft. But think in terms of
watercraft until you take off.
Parachute Descents:
- Cannot drop into or operate in an air route or controlled airspace (unless you have permission from an ATC
unit).
- Cannot drop over or into a built up area.
- Cannot drop over an open-air assembly.
ATC instructions and clearances are based on traffic known to ATC. The pilot is still the one who is ultimately
responsible for traffic avoidance.
Speed Limits:
- Max 200 knots IAS below 3000’ and within 10 NM of a controlled airport, unless you have a
 clearance.
- Below 10,000’, the limit is 250 knots IAS.
- No matter what the altitude is, you are not allowed to exceed Mach 1 (767 mph or 667 KTS).
Cruising Altitudes:
- Use magnetic track in SDA.
- Use true track in NDA.
- Cruising altitudes kick in at 3000’ AGL, not 3000’ ASL! But they are measured in ASL in terms of
numbers.
- East cross-country (000 to 179) is odd 1000’s plus 500’.
- West cross-country (180 to 359) is even 1000’s plus 500’.
CVFR – Controlled VFR
Reduced Vertical Separation Minima (RVSM) – Special rules that can come into play starting above FL 290 that
change vertical separation from 2000’ to 1000’. Designed to save fuel, allow aircraft to safely fly more
optimum profiles, and to increase airspace capacity. Normally the separation is 4000’ between levels flying in the
same direction, and 2000’ between opposing layers, but RVSM cuts these in half.
Standard Pressure Region (SPR):
- Altimeter always gets set to 29.92” Hg.
- When passing from Altitude Pressure Region to SPR, always set the altimeter after entering and before
leaving the SPR.
Altimeter Setting Region (ASR):
- In SDA, this is up to 17,999 ASL.
- Set the altimeter to the current altimeter setting or to airport elevation before takeoff. - In cruise, set the
altimeter to the nearest reporting station. This may happen multiple times en route.
- Set to the destination airport before you land.
Air Time is the time with wheels off the ground, and is used for maintenance schedules and for determining when
inspections are due.
Flight Time starts when the aircraft first moves under its own power, and ends when the engine stops. This is what pilots
log for our logbook hours, and what determines your level of experience. Flight time always exceeds air time.
You should review all of your PSTAR material while studying for your PPL.
The Transport Canada PSTAR app by Kermode Industries is a good study and memorization guide for PSTAR material.
An airport is a certified aerodrome.
Maneuvering Area – Includes runways and taxiways.
Apron – Used for loading cargo and passengers, parking, refueling, etc.
Airports have orange and white runway markers, but aerodromes have solid orange.
Night runways need two parallel rows of white lights or retro-reflective markers with lights at the ends, visible for at
least 2 NM.
Overflying an Aerodrome:
- Must be at least 2000’ AGL or 1000’ above the circuit for an en route overflight. - Being 500’
above the circuit is OK for crossing to examine the circuit or the airport.
RSC – Runway Surface Condition
RSC Reports are required when:
- Frost/snow/slush/ice are on the runway.
- Snow banks/drifts/windrows are on or adjacent to the runway.
- Sand/aggregate or anti-icing or deicing materials have been applied.
- The cleared width is less than the published width.
- Runway lights are partially or fully obscured.
- There is a significant change in conditions, including for the better.
- At a minimum inspection frequency.
CRFI are reported when there is “anything other than rain” on the runway.
If you see a number painted on a heliport, it indicates a weight limit in thousands of pounds.
CYR – Restricted Area.
CYA – Advisory Area.
Controlled Airspace:
- Airspace with defined dimensions within which air traffic control (ATC) service is available, which some or
all aircraft may be subject to.
 - IFR aircraft require a clearance to enter or operate in controlled airspace.
Types of Controlled Airspace:
- High Level Airspace: 18,000’ and above.
- Low Level Airspace: Class B, C, D, or E.
- Low Level Airways: Class E.
Low Level Airways (Victor Airways):
- Controlled low level airspace from 2200’ AGL to 17,999’ ASL.
- Normally based on VHF, ie. a VORTAC.
- The basic width is 4 NM on each side of the centerline out to 50.8 NM.
- Past 50.8 NM and onward to the midpoint of the airway, the width increases by 4.5o angles on each side of the
centerline.
- If it is a Victor Airway based on LF/MF, the boundaries change to 4.34 NM width up to 49.66 NM out, and 5o
thereafter to the midpoint. The same applies if the airway is mixed, ie. based upon a VORTAC and an NDB.
Control Area Extension (CAE):
Provides additional controlled airspace to handle IFR traffic. Surrounds and overlies the core control zone. IFR traffic is
controlled by the ACC. Usually circular with a defined radius. Extends upwards from 2200’ AGL to 17,999’ ASL, same
as an airway.
Control Zone – Usually extends upwards vertically from ground level up to and including 3000’ AGL, unless otherwise
noted.
Class A Airspace :
Extends from FL180 to FL600, and is entirely transponder airspace. IFR flights require clearance to operate, and are
provided full traffic control service. - VFR flights are not permitted to operate within Class A airspace. Also known as
High Level Airspace. Divided into three control areas in Canada. Southern Control Area (in SDA) is from FL180 to
FL600. Northern Control Area (in NDA) is from FL230 to FL600. Arctic Control Area (in NDA) is from FL270 to
FL600. Pilots must be IFR rated, and Aircraft must be IFR certified. A functioning Mode C transponder and a pressure
sensitive altimeter are also required.
Class B Airspace:
Roughly speaking, it extends from 12,500’ to 17,999’ ASL, entirely transponder airspace. - IFR flights require
clearance to operate within Class B, and are provided full traffic control service. - VFR flights require clearance to
penetrate and operate, and once inside are provided with full traffic control (just like IFR). They are designated CVFR
for Controlled VFR. CVFR must request clearance for all altitude or heading changes, and must comply with ATC
instructions. CVFR flights may be vectored, and given speed/altitude instructions provided that they stay clear of
clouds. The pilot must inform ATC if they cannot comply with an instruction. CVFR is similar to Flight Following.
Technically, Class B includes all Low Level Airspace from 12,500’ upwards, or at and above the minimum en
route altitude (MEA) for IFR aircraft, whichever is higher. indicated by hatched pattern on LO (instrument)
charts. Dark blue line on VFR charts.
Class C Airspace:
Found in some larger areas. Designated as Terminal Control Areas (TCA’s) and associated control zones. It will
extend in the upside-down wedding cake shape up to 12,500’ ASL, entirely transponder airspace. Surrounds
approximately 38 airports across Canada. IFR flights require clearance, and are provided full control service. VFR
flights require clearance to penetrate and operate, and once inside can be assigned general altitude restrictions and
heading restrictions, but are still not controlled in the IFR sense of the word, therefore cannot be ordered around like
IFR aircraft. Conflict resolution (avoidance instructions) are provided upon request, and flights should always be
advised of nearby traffic, just like flight following. If the workload is too high, VFR flights can be denied access to
Class C airspace. - The PIC has [as always] the responsibility to avoid other aircraft, maintain terrain and obstruction
clearance, and to remain in VFR weather. A pilot must communicate to ATC any concerns related to pilot
responsibilities. Aircraft must be equipped for two-way radio communication, and must maintain a continuous
listening watch. Mode C transponders required. Class C reverts to Class E (temporarily) when ATC services are not
operating. Brackets surround Class C airspace on a VFR navigation chart. Examples include Calgary, Edmonton,
Vancouver.
Class D Airspace:
Found in some larger TCA’s. It will extend in the upside down wedding cake shape up to 12,500’ ASL. Can be
designated transponder airspace, although in some airports, having a transponder will not be mandatory. IFR flights
require clearance, and are provided full control service.VFR flights must make contact with the appropriate ATS unit
before entering, but do not require a clearance to penetrate and operate within Class D. Aircraft must be equipped for
two-way radio communication, and must maintain a continuous listening watch. Pilots flying in Class D will proceed on
their own navigation, but ATC can assign altitude restrictions and heading restrictions if required for IFR traffic
separation. When workload permits, conflict resolution (avoidance instructions) are provided upon request, and flights
should always be advised of nearby traffic, just like flight following. If the workload is too high, VFR flights can be
denied access to Class D. If a Control Zone is Class D, then it will be a towered airport. Your aircraft may or may not
need a transponder. Your charts and the CFS will answer this question. - Brackets surround Class D airspace on a VFR
navigation chart. Examples include Thunder Bay, Regina.
Class E Airspace:
All low-level controlled airspace that has not been designated as class B/C/D is Class E. This includes all Victor
Airways, and some smaller Terminal Control Areas. Victor airways extend from 2200’ AGL to 12,500’ ASL (watch
this!). Some Class E TCA’s can be designated transponder airspace. All airspace above FL600 is Class E. IFR flights
require clearance to operate in Class E, and are provided full control service. However, in VMC, the pilot is expected to
keep a lookout for VFR traffic that may not be talking to ATC. - VFR flights do not require any authorization, and ATC
has no authority. However, VFR traffic may request flight following where they will rely on ATC to advise them of
nearby traffic. ATC can refuse this service if workload is high. Although ATC does not have authority over VFR, ATC
can give suggestions, or request that the VFR pilot restrict their climb to let an IFR flight go by. If the VFR pilot is not
willing to comply, the IFR flight must make the detour. Essentially, there are no special requirements for VFR in Class
E. Control Area Extensions may also be Class E. If an aerodrome/airport has a Class E Control Zone, VFR aircraft must
follow MF procedures and must also get a traffic advisory from the appropriate controlling FSS at least five minutes
prior to entering. - When a Tower (Class C or D) closes temporarily, the aerodrome/airport becomes a Class E Control
Zone with MF, and pilots need to follow MF procedures. Examples include Kenora, Brandon. Some Class E airspace in
direct proximity to a large aerodrome will be classified as transponder airspace.
Class F Airspace:
Uncontrolled, special use airspace. Either CYR or CYA. CYR is restricted, and no unauthorized aircraft may penetrate
this zone. CYA is advisory, and this area is hazardous to the operation of civil aircraft, so penetrating this zone is not
recommended. An aircraft may fly through, but it is not ATC’s problem to provide separation. - If a certain area is
temporarily designated as CYR or CYA, it will be done by NOTAM. - Usually designated as Class F due to either
military operations or hazards (forest fire, experimental testing, training, soaring, etc.). Can be active 24/7, during only
certain periods of the day, or maybe only by NOTAM. IFR are not permitted in or cleared through by ATC unless the
pilot has obtained prior permission from a user agency, has an Altitude Reservation, or is conducting a Contact or Visual
approach. - Unless otherwise specified, the radio frequency of 126.7 MHz should be monitored at all times.
Class G Airspace;
ATC does not have the authority or obligation to provide service for anyone. IFR flights do not require clearance to
operate, however, they are required to proceed in accordance with all IFR procedures. VFR flights require no clearance,
but they must remain VMC at all times. The only information service available is provided by the appropriate FIC on
126.7 MHz. - Class G accounts for 99% of Canadian airspace. Some remote parts of Canada are Class G below FL180.
These areas are tinted green on the Lo charts. Airspace that is Class G to 12,500’ but with Class B above that, is tinted
green with white lines. Low Level Air Routes (similar to Low Level Airways, but uncontrolled) start at the surface
(rather than at 2200’ AGL), and are designated by two letters and a number, ie. AR34.
While Low Level Air Routes are uncontrolled, it is important to remember that part of an LLAR may pass through
controlled airspace, even though an LLAR does not “create” controlled airspace.
Minimum En Route Altitude (MEA) - the lowest published altitude between radio navigation fixes that assures
acceptable navigational signal coverage and meets obstacle clearance requirements between those fixes.
Transponder Airspace:
A transponder is required in Class A/B/C. It may or may not be required in Class D and/or E. If a transponder
or Mode C fails, proceed to the next aerodrome of intended landing.
There are four categories of VFR Weather Minima:
1. In the control zone.
2. In other controlled airspace.
3. In uncontrolled airspace greater than or equal to 1000’ AGL.
4. In uncontrolled airspace below 1000’ AGL.
Knowing all VFR rules is absolutely critical for your flight exam. You must memorize them perfectly!
VFR Weather Minima, Control Zones:
- 3 miles visibility.
- 1 mile horizontally from clouds.
- 500 feet below clouds.
- 500 feet above ground.
 - If you have to go to SVFR, you must remain clear of clouds above, and your visibility can drop to 1 mile. In
addition, for SVFR, you must ask for a clearance or permission to enter a control zone.
VFR Weather Minima, Other Controlled Airspace:
- Same as above, except disregard the requirement to be 500’ AGL. This is a given, because controlled airspace that
is not a control zone is up high.
VFR Minima at or above 1000’ AGL , Uncontrolled Airspace:
- 1 SM visibility by day, 3 SM visibility by night.
- 500’ below clouds vertically.
- 2000’ horizontally from clouds.
VFR Minima below 1000’ AGL, Uncontrolled Airspace :
- 2 SM visibility by day, 3 SM visibility by night.
- Clear of clouds.
- The visibility requirement is greater when we are below 1000’ AGL because you are likely closer to an airport and
because there is likely more traffic.
Special VFR Requirements:
The pilot must request it, ATC must also then authorize. ATC will never instruct SVFR, although they may often hint at
it. Must retain visual contact with the ground. Minimum visibility is 1 SM (except for helicopters which are ½ SM).
Airplanes can arrive/depart daytime. At night, airplanes can only arrive, not depart. Helicopters can arrive/depart either
day or night. Must operate clear of clouds at all times.
VFR Over-The-Top (OTT) Requirements:
- Special endorsement.
- Must be at least 1000’ above the clouds vertically.
- Permitted in daytime only, and only during the cruise portion of the flight.
- Horizontal distance of at least 5 SM from cloud layers at your altitude.
- When operating between two cloud layers, the vertical separation of layers must be 5000’. - The destination
forecast must be scattered/few/clear, ground visibility of at least 5 SM, and no
precipitation/fog/thunderstorms or blowing snow. This forecast must be 1hr prior and 2hr afterwards when
using a TAF, or 1hr prior and 3hr afterwards when using a GFA.
IFR aircraft have priority under IFR conditions! So if you request SVFR when there is an IFR aircraft incoming,
you may be denied or deferred. Wait for the IFR aircraft to clear, then ask again.
Airworthiness Defect (AD) – Special maintenance outlines or items that are issued by an aircraft manufacturer
and/or aircraft component manufacturer. Must be rectified, certified, and signed as airworthy by an AME.
Annual Airworthiness Information Report (AAIR) – Does not affect the Certificate of Airworthiness, but must be
submitted to Transport Canada annually or you might get a fine.
You must have a radio and be listening on the appropriate frequency if you’re going into an MF area. MF
boundaries are usually 5 NM radius and 3000’ AAE.
Remote Aerodrome Advisory Service (RAAS) – Controlled remotely by a FSS. Class E. Dashed lines in a circle
around an airport (on a chart) mean that it is controlled, and Class E. Therefore, it is MF, whether on-site FSS or
RAAS.
The letter A in front of the frequency on a chart means that it is an uncontrolled ATF frequency, non mandatory.
These typically have a radius of 5 NM and extend to 3000’ AGL. NORDO operations are permitted. For an ATF
with no published frequency, use 123.2 MHz.
The letter M in front of a frequency means that it is MF. A thick boundary box tells you that the FSS and
controller are on site.
The only way that you’re permitted to enter an MF area with no radio (NORDO) is if there is a ground station
operating, you’ve given them prior notice, they agree, and you arrive at a pre-specified time. “PRO” in the CFS
stands for standard procedures.
If you’re in a Class E Control Zone, you’d better be talking to someone. But if you’re transiting Class E
Airspace, you may not necessarily be talking to anyone.
Try carrying a spare handheld and/or a cell phone for comm failures.
In an emergency, one good option may be to divert to an uncontrolled airport that may not have mandatory frequencies.
But never land at an unsuitable airport or fly beyond safe fuel range. If absolutely necessary, enter controlled airspace
with caution and follow the comm failure procedures.
Squawk 7600 for communications failures.
Communication failure Light Signals, while in the air:
Green steady – cleared to land.
 Green flashing – return for landing.
Red steady – Continue circling.
Red flashing – unsafe, don’t land.
Red pyrotechnical – military, don’t land.
Communication failure Light Signals, on the ground:
Green steady – cleared for takeoff.
Green flashing – cleared to taxi.
Red steady – stop.
Red flashing – Taxi clear of landing area in use.
White flashing – return to starting point.
Blinking runway lights – vacate immediately (usually a signal to vehicles and pedestrians). The
international emergency frequency is 121.5 MHz.
Practice interceptions are not carried out on civil aircraft. If you’re being intercepted, it’s real and it’s serious.
The CFS lists interception procedures in the emergency section.
Air Defense Identification Zones (ADIZ):
- You need a flight plan or itinerary to enter or depart.
- Penetration of ADIZ must be within 20 NM and 5 minutes of flight plan.
60,000 ASL is the International Standard for the beginning of outer space. But others say that “space” starts about 80km
up, at the base of the thermosphere.
Note that Canada’s ADIZ’s touch or overlap many of the coastal boundary edges of Nova Scotia, Newfoundland,
Vancouver Island, Haida Gwaii, and coastal BC/north.
Emergency Security Control of Air Traffic Plan (ESCAT):
- Was used once historically, during 9/11.
- Provides for security/control of all civil and military air traffic by the NORAD commander. - If you hear
an ESCAT test, you must report every thirty minutes, even if flying in uncontrolled airspace.
- You must comply with all ATC/FSS instructions.
- Sometimes, this system is tested without prior knowledge.
Minimum Equipment List (MEL) – A list of items that are required, and also that are allowed to be inoperative. It is
only required on aircraft that are over 12,500 pounds and turbine powered. MMEL is the Master MEL.
When an AD is in conflict with an item listed in the MEL, the AD prevails.
Navigation lights are red on the left (port), green on the right (starboard), and white on the tail. The anti-collision light
is flashing, colored red or white or both.
If a person is carried on a stretcher or in an incubator, or planning to parachute out of the aircraft, restraints may be
used in place of seat belts.
All persons in an aircraft must wear seat belts when landing, taking off, moving on the surface, or at the direction of
the PIC. The pilot must wear a seat belt at all times, even in cruise.
You aren’t allowed to fly into current/forecast reports of icing conditions unless your aircraft has anti-icing
equipment.
The pilot at the flight controls of an aircraft shall use an oxygen mask if:
1. The aircraft is not equipped with quick-donning oxygen masks and is operated at or above flight level 250; or
2. The aircraft is equipped with quick-donning oxygen masks and is operated above flight level 410.
An ATC unit may authorize an aircraft to operate without a transponder but within airspace where a transponder is
required if ATC receives and approves the request prior to the aircraft entering their airspace, and if it is not likely to
affect aviation safety.
You cannot take off in an aircraft that has an open snag.
In addition to a comprehensive journey log for all maintenance items, each aircraft will have separate technical logs
for the airframe, each engine, and each variable pitch propeller. The journey log and the technical logs are never
allowed to be stored or transported together, to help ensure that they cannot be accidentally lost or destroyed.
When starting a new volume of a journey log, you must carry over enough entries to ensure an unbroken
chronological number.
You are not permitted to make a single entry into a journey log for a series of flights unless the aircraft is operated by
the same PIC throughout the series of flights, and an approved daily flight record is used. This variation on SOP’s is
suitable for use at a Flight School, but probably not for a PPL.
Elementary Work – A form of simple maintenance that is not subject to a maintenance release, ie. replacing tires,
bulbs, fuses, spark plugs, checking compression, etc. The owner can do this work on a privately registered aircraft, but
for a commercially registered aircraft, you must be supervised by an AME for the first time that you perform the work.
An aircraft that has been subjected to an abnormal occurrence cannot be flown until the aircraft has been inspected
for damage. An inspection can be performed by the PIC only if disassembly is not required.
Aviation Occurrence – Any accident or incident associated with the operation of an aircraft.
Accident:
- A person sustains serious injury or is killed.
- Aircraft sustain substantial damage.
- Aircraft are missing or inaccessible.
Reportable Aviation Incident:
- Aircraft fails to remain on the landing or takeoff area, lands with the gear retracted or drags a wing tip, an
engine pod, or any other part of the aircraft.
- Crew member incapacitation that poses a threat to safety.
- Depressurization occurs that necessitates an emergency descent.
- A fuel shortage results in a diversion or requires approach and landing priority. - The
aircraft is refueled with the incorrect type of fuel or contaminated fuel.
- A collision, a risk of collision, or a loss of separation occurs.
- A crew member declares an emergency or requires priority handling.
- A slung load is released unintentionally or as a precaution.
- Any dangerous goods are released in or from the aircraft.
- An engine fails or is shut down.
- A transmission gearbox malfunctions.
- Smoke or fire occurs.
- Difficulties are encountered in controlling the aircraft.
Commercial aircraft need to have an ERP (Emergency Response Plan).
Civil Aviation Daily Occurrence Reporting System (CADORS):
- This system allows aviators and investigators to report preliminary data on any unusual occurrences. - CADOR
items: student getting lost, flight plan not closed, accidents and incidents, taking off without a clearance, etc.
- Can be found on the Transport Canada website, and is visible to the public. It is worth studying some of them.
Nav Canada is a private, not-for-profit company. It is responsible for ATS, ATC, FSS/FIC, weather briefings, and
electronic navigation aids.
ATC is provided through:
- Control Centers (ACC’s).
- Terminal Control Units (TCU’s).
- Control Towers.
Terminal airspace typically starts at 2200’ AGL, and often extends out for 35 NM. It often extends to the bottom of
Class B airspace, which starts at 12,500’ ASL. A TCU controller may work out of an ACC, and an en route controller
may also. En route controllers will be in charge of Class E airways.
A Class E airport with MF will not have a tower, however, it will have a controller working out of a FSS. This is the
only case where a FSS will have an actual controller, although you can find lots of other staff in a FSS.
The en route portion of your flight can include flight time in both Terminal Airspace and Class E airways. Terminal
Control Service is provided within specified control areas by ACC’s or TCU’s.
The eight Flight Information Centers (FIC’s) service the eight Flight Information Regions (FIR’s), for weather
briefings and flight planning services.
A FSS is a branch/offshoot of a FIC. Sometimes, FSS staff are physically split between a FSS in a smaller city and a
FIC in the main regional center. FSS staff also coordinate Vehicle Control Services for airport vehicles.
Flight Information Services En route (FISE) – A frequency used by FSS or FIC for weather briefing and flight
planning info, which is easy for pilots en route to access via their VHF radio.
Dialup RCO (Radio Communications Outlet) is known as a DRCO. To operate, key your mic 4 times on the
published frequency to activate it. It then calls a distant ATS unit (via telephone landline).
Community Aerodrome Radio Station (CARS):
- Established at certain isolated airports, operated by territorial or provincial governments, or by ATS. -
Interconnected with a FSS.
- They can provide local data, and they also accept and pass on PIREPS and flight plan itineraries.
UNICOM:
Operated by a private agency that provides private advisory station service at uncontrolled aerodromes. Not
official, and info provided may or may not be used (at the discretion of the pilot). Used at airports with low
traffic volumes and typically with no control tower. Some UNICOM stations are not staffed.
Automatic Terminal Information Service (ATIS):
-Broadcast on a specific separate frequency. frequently.
- Contains non-control info. - Each successive ATIS message throughout a day
- Broadcast repeatedly, in a continuous audio loop. gets a new phonetic identifier.
- Usually updated hourly, but sometimes more
NavCan publishes a book that reviews basic VFR phraseology. It’s fairly handy. Here’s a link: When a controller
gives a radar position, it is based on the track (path over the ground), not on the heading of the aircraft. The controller
just sees which way the aircraft is traveling and can’t account for the fact that an aircraft may be pointed on a different
heading to account for wind drift.
A controller may tell you to join a circuit on “left base” or “left downwind” when using a right-hand circuit, or on
“right base” or “right downwind” when using a left-hand circuit. These instructions would imply that you are using a
circuit that is a mirror of the normal one in effect at the airfield. You can’t do this on your own at
an uncontrolled field, because at uncontrolled fields, there are only two legal ways to join the circuit: downwind, and
crossing midfield. However, at a controlled field, the controller can give you a wider variety of options (including
unconventional options), depending on circumstances at the time.
When a Class C or Class D towered airport closes (such as during nighttime), it becomes a Class E mandatory
frequency.
The usual radius for both ATF and MF is 5 NM out from the airport up to 3000’ (double-check this, as I believe one
is AAE and one is AGL).
ATF usually uses one of the UNICOM frequencies (there are approximately eleven of them). Where there is no
ground station, the ATF would be 123.2 MHz.
Statute Mile = 5280 feet.
Nautical Mile = 6076.1 feet or approximately 1.15 statute miles.
Always join the circuit at circuit height!
Some other frequencies are starting to replace 126.7 MHz as the FISE frequency, as 126.7 is sometimes becoming a
broadcast-only frequency. These other frequencies are often in the 123’s.
Land And Hold Short Operation (LAHSO) minimums:
- 1000’ ceiling and 3 SM visibility.
- Reported braking action not less than good.
- Runway must be bare.
- Tailwind of less than 5 knots is acceptable.
- Maximum crosswind component of 15 knots.
- ATC must include specific instructions.
- Pilots must read back clearance.
- Pilots must remain 200 feet short of the closest edge of the runway being intersected.
Progressive Taxi – If you are uncertain about taxi instructions, because they are too complex or because you are
unfamiliar with the airport, ask for progressive taxi. The controllers will give you step-by-step instructions in a series,
rather than all at once.
Hypoxia:
-Low oxygen. - Can cause unconsciousness.
- May make you feel euphoric. - Smokers are more susceptible.
- Impairs night vision, slows reaction time.
You must use supplemental oxygen above 13,000 feet, and also if you’re above 10,000 feet for more than thirty minutes.
Recommended at night if you’re flying above 5,000 feet.
The atmosphere is thicker around the equator.
Types of Hypoxia:
1. Hypoxic: Lack of oxygen from changes in altitude.
2. Anemic: Due to a person’s blood’s inability to absorb oxygen.
3. Stagnant: Due to blood pooling in areas.
4. Histotoxic: Due to our body’s cells’ inability to absorb oxygen.
Dysbarism – Caused by gasses trapped in the body that expand or contract in body cavities. Can cause toothaches,
ear/sinus pain, or abdominal pain. Most evident during descents.
Barotrauma – Physical damage caused by any type of dysbarism.
If a passenger reports ear pain, level off for a bit, and suggest yawning, swallowing, or chewing gum. Atmospheric
pressure is only 50% at 18,000 feet.
Flying above 25,000 feet in an unpressurized aircraft can lead to “bends” or decompression sickness.
If you’ve been diving, don’t fly anything up to 8,000 feet for at least twelve hours. If you need decompression stops, OR
if the flight is going to go above 8,000 feet, wait twenty-four hours after your dive.
When scanning for other aircraft, segment the windshield, use peripheral vision rather than center-of-view, don’t stay
staring at any one area for too long.
Noise levels in the cockpit are usually high. Earplugs or noise canceling headphones should be worn to protect your
hearing.
Spatial Disorientation – Sense of confusion about your position or movement.
Vertigo – Sense or hallucination of spinning or rotating even after motion has stopped.
Vestibular Illusions – When an aircraft becomes established in a turn, the fluid in your inner ear can incorrectly indicate
that the turn has stopped, or if the turn stops, fluid can indicate a turn in the opposite direction. This is especially strong
at night.
Visual illusions can be caused by at least a dozen things. Scan and trust all instruments regularly, no matter what your
senses tell you.
Do not take medicines for airsickness while piloting, as they usually cause drowsiness and impair judgment.
Don’t fly within 24 hours of local anesthetics or until a doctor gives approval for a general anesthetic. Wait 48 hours
after donating blood.
Hyperventilation – Breathing at a faster and/or deeper rate than the body requires for good oxygenation at the existing
work level. You need to slow down and get more carbon dioxide into your system.
Smoking can severely limit your career as a pilot.
Time of Useful Consciousness (TUC) – The amount of time that an individual is able to perform flying duties efficiently
in a period of low oxygen availability.
Tensing calf and thigh muscles increases our tolerance to high “G” maneuvers.
Common responses to stress can include omission error, queuing, approximation, and fixation.
Dehydration occurs more quickly at altitude. Bring water/juice on a flight, but try to avoid caffeine or carbonated drinks.
Decision Making Process: (GRADES) Gather, Review, Analyze, Decide and Do, Evaluate, (Start over, if necessary)
Types of Stress – Acute is temporary, chronic is long term.
Correct use and following of checklists is a critical skill for anyone trying to get a license, and throughout a pilot’s
career.
Snag – A note to maintenance personnel.
CRM – Crew Resource Management
Emergency Procedures:
1. Aviate.
2. Navigate.
3. Communicate.
Humans are designed to maintain spatial orientation on the ground. The flight environment is hostile and unfamiliar.
VFR requires that you are able to see a horizon. Even birds are unable to maintain spatial orientation and fly safely when
deprived of vision (clouds, fog, etc.).
Foveal Vision – Central vision, involved with the identification of objects and the perception of colors.
With peripheral/ambient vision, motion of the surrounding environment produces a perception of self motion even if we
are standing or sitting still.
When the natural horizon is obscured, the attitude (for pitch) can sometimes be maintained by visual reference to the
surface below.
Up-sloping Runway – May produce the visual illusion of a high altitude final approach. Down-sloping Runway – May
produce the visual illusion of a low altitude final approach.
Wide Runway – May produce the visual illusion of a low altitude final approach.
Black Hole Approach – A final approach at night (with no stars or moonlight) over water or unlighted terrain to a
lighted runway beyond which no horizon is visible. You may have the illusion of being upright, and may perceive the
runway to be tilted left and up-sloping.
Especially dangerous is a black hole approach with no lights before the runway and city lights or rising terrain beyond.
 This may produce the visual illusion of a high altitude final approach. Autokinetic Illusion – The impression that a
stationary object is moving in front of the airplane’s path. It is caused by staring at a single fixed point of light in a
totally dark and featureless background.
False Visual Horizon references:
-Flying over a banked cloud. - Night flying over featureless terrain.
- Mountainous terrain can be misleading. - Good ground lights but dark, starless sky.
Spatial Disorientation – A mismatch between visual, vestibular, and proprioceptive sensory inputs. Approximately
5-10% of GA accidents can be attributed to spatial disorientation. Ninety percent of those accidents are fatal.
Vestibular System:
-Inside the ears. acceleration.
- Organs of equilibrium. - Otolith organs (utricle and saccule) detect
- Semicircular canals detect changes in angular changes in linear acceleration and gravity
Your semicircular canals are three half circular, interconnected tubes. They are the equivalent of three gyroscopes located
in three planes which are each perpendicular to the others.
Vestibular Illusions:
- Occur primarily under conditions of unavailable or unreliable external visual references. - Leans: Caused by a
sudden return to level flight following a gradual and prolonged turn that went unnoticed by the pilot.
- Graveyard Spin: Occurs when you enter a spin. You will initially have a sensation of spinning in the same
direction as your spin. However, as it continues, you have the sensation that the spin is progressively
decreasing. If you apply rudder to stop the spin, your body may trick you, then you overcompensate.
- Graveyard Spiral: Associated with a return to level flight following an intentional or unintentional prolonged
bank turn. After perhaps twenty seconds in a banking turn, your body tricks you into thinking that you are
no longer banking. Very dangerous.
- Coriolis Illusion: Involves the simultaneous stimulation of two semicircular canals with a sudden tilt of the
pilot’s head (sideways/forward/back) when the aircraft is turning. Can produce the almost unbearable sensation
that the aircraft is rolling, pitching, and yawing, all at the same time.
Human exposure to rotational acceleration of two degrees per second or lower is below the detection threshold of the
semicircular canals. Remember that a standard rate turn is only three degrees per second, or barely detectable.
Levelling the wings after a turn may cause the illusion that a plane is banking in the opposite direction.
In a spin, the ball (in the inclinometer) tells you nothing. Remember this: “Step on the sky, or the wing that is high.”
Otolith Organs:
1. Saccule: Detects gravity changes in the vertical plane.
2. Utricle: Detects changes in linear acceleration in the horizontal plane.
Somatogravic Illusions involve the utricle and saccule. These happen most frequently when there are not any exterior
sensory inputs. Types include:
1. Inversion: Steep ascent (forward linear acceleration), followed by a sudden return to level flight, can make you
think that the aircraft is inverted.
2. Head Up: Sudden forward linear acceleration makes you think that the aircraft is pitching up significantly.
This occurs most commonly during an overshoot, and is especially dangerous at night. 3. Head Down: Sudden
linear deceleration during level flight that makes the pilot perceive a sudden steep pitching forward. Common on
short finals. A risk is that the pilot reacts by pitching up, and stalls.

Proprioceptive Receptors – Located in the skin, muscles, tendons, and joints. Play a small role in maintaining spatial
orientation.
Preventing Spatial Disorientation:
1. Stay in three-mile visibility VFR conditions.
2. Don’t push the weather.
Airsickness is different from spatial disorientation. Symptoms of airsickness include vertigo, loss of appetite, salivation
and swallowing, burping, stomach awareness, nausea, retching, vomiting, urge for a bowel movement, cold sweats, skin
pallor, sensation of fullness in head, mental confusion, apathy, drowsiness, difficulty focusing, visual flashbacks, eye
strain, and blurred vision.
Airsickness is uncommon among experienced pilots. You build a tolerance. Avoid fatigue, alcohol, drugs/medications,
and stress.
If your attention is focused on flying the aircraft, you are less likely to become airsick. Never take drugs for motion
sickness!
If you become airsick it can help to:
 - Open windows/vents.
- Put your head against the seat headrest.
- Keep your eyes on a point outside the aircraft.
Night – Officially lasts from the end of evening civil twilight to the start of morning civil twilight. Or when the center of
the sun’s disc is 6o below the horizon (which is approximately 25 minutes after sunset, or 25 minutes before sunrise).
Night Flying:
- Bring at least one flashlight, plus spare batteries.
- Red filtered lights are the best.
- Headlamps are convenient.
- You need a flashlight to inspect the outside of the aircraft.
Always check NOTAMs, every time you fly. Including at night.
Using a Landing Light is technically not a legal requirement if you are a PPL with no passengers, but it is smart to
always use it for all takeoffs and landings.
Recency Requirements:
- Five takeoffs and landings at night in the last six months.
- Landing light must be serviceable.
- For commercial (CPL), recency is three takeoffs and landings in ninety days.
CARS for Night Flying:
- Three mile visibility for VFR, unless using SVFR.
- SVFR is not authorized for night departures.
- You need 45 minutes of reserve fuel, not 30 minutes.
ARCAL Lighting:
1. Type J: Key the mic five times in five seconds, timer resets for approximately fifteen minutes.
2. Type K: Key the mic seven times initially, put it on high lighting, but if you follow up by five or three times
you’ll lower the intensity to medium (5) or low (3).
VASI Lights – Designed for a three degree glide path. For a three bar VASI system, a small craft would ignore the top
light, and a large aircraft would ignore the bottom lights.
PAPI – Precision Approach Path Indicator. Has four lights side-by-side.
Averted Vision – Looking a few degrees off center when trying to see an object at night. You have a central blind spot
because you have no rods in the fovea.
Night Illusions:
- Autokinesis: Objects appear to shift.
- False Reference: Stars or lights near the horizon.
- Venus & Sirius: False aircraft.
- Night Myopia: Dilation, inability to focus.
- Somatographic: Acceleration with pitch.
Make sure that you taxi more slowly at night. Speed is deceptive and depth perception is reduced. And make sure that
your brakes are on firmly.
International Virtual Aviation Association ( IVAO) – A free service to enthusiasts participating in the worldwide flight
simulation community.
Moving between two aprons is acceptable and does not require permission from ground control (although in a busy
airport, it would often be a wise courtesy).
Crossing a runway is only permitted if your taxi instructions took you past that point, and if you were not told to hold
short of the runway that must be crossed.
Always hold short of your takeoff runway, unless you have been told that you may line up. Being told to line up is not a
clearance to take off! After lining up, you must still wait for a takeoff clearance.
If you are told to line up on a runway and you are approaching that runway in a straight line (from before the threshold),
stopping at the hold short line for the runway does not mean that you are lined up! You must still cross the hold short line
(as long as you haven’t been told to hold short), and only then, once you are onto the actual runway and stopped, are you
considered to be lined up.
There is a difference between ATS, which stands for Air Traffic Services, and ATC, which stands for Air Traffic
Controller. “Services” encompasses a broad range of services, while “Control” is a specific type of service. All
controllers provide ATS. However, not all entities which provide ATS are classified as controllers. I have occasionally
used these two acronyms in a slightly synonymous manner within these study notes, however, you must learn to
understand the distinction.
 CHAPTER 4 - NAVIGATION
Using the E6B:
- Front Outer scale: Miles traveled, miles per hour, gallons used, gallons/hour, true airspeed. - Front
Middle scale: Time in minutes, indicated airspeed in mph or knots.
- Front Inner scale: Time.
- Numbers on the outer and middle scales can have their decimal places shifted. This cannot be done with the inner
scale (time).
- The black triangle on the middle scale represents one hour.
Time/Distance/Speed Calculations - To figure out time to travel a certain distance, line the black triangle on the speed in
knots, and under the corresponding number of nautical miles you’ll see the number of minutes required. You can also do
this with mph and statute miles.
Short Time & Distance – Use the small arrow at 36 (says “seconds”) to represent our pointer. The middle scale is then
represented by seconds instead of minutes. The inner scale is then represented by minutes instead of hours.
Fuel Consumption – Same as time and distance, just replace mph with gallons per hour, and miles with gallons.
Density Altitude – To figure out the true airspeed, you must know the pressure altitude, the temperature you’re flying
at, and the indicated airspeed. Use the right windows, line up the CAS (from the IAS) on the middle scale, and you’ll
see TAS on the outer scale. Density altitude can then be seen in the labeled window.
For True Altitude – Use the air temperature and pressure altitude in the left window. The outer scale will read the true
altitude and the inner scale will read the calibrated altitude.
Distance Conversion – This is quite simple, and is done entirely on the outer scale. There are arrows for nautical
miles, statute miles, and kilometers.
Correcting for Drift – See the E6B manual, or read the instructions printed on the E6B. On the back side of the E6B, the
inner wheel is the spinning azimuth, and the outer wheel is the true index.
Meridian – Semi circles that run from north to south and join at the Earth’s true poles. A meridian is half of a great
circle.
Prime Meridian – Zero degrees longitude, passes through Greenwich.
Latitude and Longitude (Meridians and Parallels)
The Equator is an imaginary circle equidistant from the poles of the Earth. Circles parallel to the Equator (lines running
east and west)are parallels of latitude. They are used to measure degrees of latitude north or south of the Equator. The
angular distance from the Equator to the pole is one-fourth of a circle or 90°. The 48 conterminous states of the United
States are located between 25° and 49° N. latitude. The arrows in figure 8-2 labeled “LATITUDE” point to lines of
latitude.
Vertical meridians of longitude are drawn from the North Pole to the South Pole and are at right angles to the Equator.
The “Prime Meridian” which passes through Greenwich, England, is used as the zero line from which measurements are
made in degrees east and west to 180°. The Prime Meridian is located at Greenwich because that is the location of the
British Naval Academy that invented longitude and latitude for navigation. The arrows in figure 8-2 labeled
“LONGITUDE” point to parallel lines of longitude. Any specific geographical point can thus be located by reference to
its longitude and latitude. Toronto, for example, is approximately 44° N. latitude, 79° W. longitude. Winnipeg, is
approximately 50° N. latitude, 97° W. Longitude.
International Date Line – Located at 180o longitude, opposite the prime meridian. This is where the date changes.
- One hour (of time) is equivalent to 15o of longitude in rotation.
The equator, at 0o latitude, is both a great circle and a rhumb line.
Azimuth – An angular measurement in a spherical coordinate system. The vector from an observer (origin) to a point of
interest is projected perpendicularly onto a reference plane; the angle between the projected vector and a reference
vector on the reference plane is called the azimuth. An example is the position of a star in the sky. The star is the point of
interest, the reference plane is the horizon or the surface of the sea, and the reference vector points north. The azimuth is
the angle between the north vector and the
perpendicular projection of the star down onto the horizon.
Great Circle – Any circle that cuts a sphere (such as the Earth) in half. A great circle represents the shortest distance
between two points.
Small Circle – Any circle slicing a sphere that isn’t a great circle.
A great circle does not cross meridians of longitude at a constant angle, so an aircraft’s heading must be changed
frequently to follow a track that is a great circle.
Rhumb Lines:
 A curved line on the earth that cuts all meridians through which it passes at the same angle. All parallels of
latitude (including the equator) are rhumb lines. They offer navigators the advantage of following a constant
heading, with the disadvantage of not being the shortest distance between two points.
Magnetic Variation (declination) – The angle between magnetic meridians and true meridians.
To convert True to Magnetic, you subtract easterly variation (east is least, west is best). This is what you will do for
your navigation log. You might have to go in the opposite direction (M to T) on the written exam.
Isogonic Lines – Represent constant magnetic variation. Dashed on a map. They can occasionally have minor bends,
due to local disturbances (ie. lots of iron ore in an area).
Agonic Line – The line of 0o variation. There is one in each of the eastern and western hemispheres.
Magnetic Deviation – Induced by metal and radio equipment in the aircraft.
Swinging the Compass – When a compass is fitted with correction magnets that are adjusted to correct the deviation.
Compass Deviation Card – Notates results after someone “swings the aircraft.” The same “east is least, west is best”
applies to deviation.
Track:
- A straight line as it has been drawn on a flat map (well, depending on the projection used on the map).
- Tracks are typically True, on the VNC and VTA charts.
- Be aware that a Lo chart compensates for variance, so the track will be magnetic. - A second definition is
possible: a track can also be described as the path that the aircraft travels across the ground.
- A GPS can be set to either true or magnetic, but true is typical.
Heading:
- The direction that the aircraft’s nose is pointed in.
- In a navigation log, you usually start out as true, then correct to magnetic (by correcting for variation).
- The heading can be substantially different from the track, depending on wind speed and direction. True
airspeed must be calculated based on positional error, altitude, and temperature. Ground speed must be calculated
based on wind speed and direction.
Bearing – An object’s position as measured clockwise from a meridian.
Drift – When the wind blows from the side and causes an aircraft to move away from its intended track.
Air Position – The theoretical position of an aircraft or missile at a given moment, assuming it to have been
unaffected in flight by wind. Also known as a no-wind position.
Types of charts include: VNC, VTA, CFS, WAS, DASH, LO, HI, and CAP.
VFR Navigation Chart (VNC):
This is the VFR chart for low to medium altitudes, the most important en route chart for small GA aircraft. Easiest
to navigate at altitudes of up to around 7500’ AGL. Created by Lambert Conformal Conic Projection. Lines drawn
on this map are great circles. Scale is 1:500,000, or one inch equals 8 SM. VNC are usually updated approximately
once every two years, whenever significant updates are needed.
VFR Terminal Area (VTA):
This is the VFR chart for low altitudes, the most important “close to aerodrome” chart for small GA aircraft
operating out of airports that are large enough to have such a chart. Created by Mercator Transverse Projection. A line
drawn on these charts will be a rhumb line. Scale is 1:250,000, so one inch equals 4 SM. Valid times are based on
changes. This chart is updated approximately every two years, based on whenever significant updates are needed.
There are VTA charts for Calgary, Edmonton, Montreal, Toronto, Vancouver, Winnipeg, and half a dozen other
airports.
Standard Parallel:
- The line of latitude in a conic or cylindrical projection in a normal aspect where the projection surface touches the
globe.
- The projection shows no distortion at the standard parallel (which visualizes as a ring through a flat map).
- It is possible for a standard parallel to touch the surface of the cone once (tangent conic) or twice (secant
conic).
Lambert Conformal Conical projection:
- A conic map projection used for aeronautical charts.
- Used on VNC charts.
Transverse Mercator projection:
- A cylindrical map projection which is the standard for nautical navigation because of its ability to represent
lines of constant course (rhumb lines) as straight segments that conserve the angle with the meridians.
- On a world map, the areas at the poles are extremely distorted.
 - Used for VTA charts.
Verification Order for charts:
- Make sure the VNC/VTA charts are valid.
- Next, check the “Flight Planning” section in the CFS.
- Finally, check the NOTAM’s.
- The updating sequence is NOTAM 🡪 CFS 🡪 VNC/VTA.
Lo & High charts:
For IFR. Below 18,000’ is Lo, and at/above 18,000’ is High. Uses lambert conformal conic projection (great circles).The
scale varies from chart to chart. Depict radio aids, airports, and other points of interest to aviation, but no topographical
features. Valid for 56 days, dates of validity on the front page. Ten different coverage areas for Lo charts. Six different
coverage areas for High charts. Charts are smaller in areas of high population and aviation density.
Canada Flight Supplement (CFS):
- Joint civil/military publication.
- Information about all Canadian and North Atlantic registered and certified aerodromes. - Revised
and updated every 56 days.
- Includes a general section, aerodrome directory, flight planning, radio navigation and
communications, military, and emergency.
Canada Air Pilot (CAP):
- Amended and republished every 56 days.
- For IFR: Standard instrument approach procedures, and noise abatement procedures. - Contains
SID’s and STAR’s.
- Different versions for each region. Seven volumes in total, plus CAP GEN which has general pages for all
volumes, plus a French version for Quebec.
Water Aerodrome Supplement (WAS):
- Has a directory of all aerodromes shown on VFR charts.
- Revised and reissued annually.
Designated Airspace Handbook (DAH):
- Lists all the airspace and classes in Canada.
- Not well known, but very valuable.
- Contains contact info for CYA’s and CYR’s.
The WAC, or World Aeronautical Chart, is a type of chart that was discontinued by Nav Canada in 2010, and is no
longer authorized for operational use. It was replaced by the VNC and VTA charts.
The VTPC Chart refers to the VFR Terminal Procedures Chart. When important information about an aerodrome
cannot be described by the aerodrome sketch or table in the CFS, a VFR Terminal Procedures Chart is published. The
chart contains information on conventional or area navigation procedures for arriving flights established on the basis of
airspace organization at the aerodrome.
For the exam, know your chart legends:
- VFR charts: VNC and VTA.
- IFR charts: High and Lo.
- CFS.
The Longest Runway Distance (LRD) is listed to the nearest one hundred feet, but the split for rounding up or down is
not in the middle, in order to be conservative in a safety sense. It is actually at the 69.5 foot mark of each hundred feet of
runway. For example, LRD 53 means a runway length between 5270 and 5369 feet in length.
PNR – Prior Notice Required
PPR – Prior Permission Required
CYD – Airspace, Dangerous

Maximum Elevation Figure (MEF):

- Large digit is thousands of feet, a small number is hundreds.
- Feet ASL, rounded up to the nearest 100 for safety.
- Denotes height of the highest feature in each quadrangle, including terrain and obstructions.
Hypsometric Tints – Shadings that illustrate approximate elevations on a chart. The scale will show the highest point,
obstacle or terrain in feet.
Non-Perennial Lake – May be dry at certain times of the year, similar to an ephemeral stream.
CFS Sections:
- General Section: Legends for VNC/VTA/VTPC charts, explanation of the A&F directory.
-Aerodrome & Facility Directory: Alphabetical listing with comprehensive facility information about all
registered land aerodromes in Canada.
- Planning Section: This is a how-to guide for flight plans/itineraries, position reports, PIREP’s, equipment code
list, transponder operation information, airspace summary, cruising altitude order, weather minima, Koch
chart, VFR chart updates.
- Radio Navigation/Communications: Info about various navigation and communication aids. - Military
Flight Data & Procedures: Info for military.
- Emergency Section: Transponder codes, light signals, ELT use, communications failure, intercept
procedures.
Obstacle Clearance Circle:
- Lists the highest obstacle altitude above sea level and 1000’ rounded up to the nearest 100’ increment.
- The radius of the area of the control zone is specified on the outer ring of the OCC.
Midnight can be 2400 on the 24hr system.
Mean Solar Day – The interval between two successive passes of the sun over a given meridian of longitude.
The terms longitude and mean time are interchangeable:
- One Time Zone = One Hour of the Earth’s rotation = 15o of Longitude.
- One minute of the Earth’s rotation = 15’ longitude.
- One second of the Earth’s rotation = 15” longitude.
Local Mean Time (LMT) – The specific time at a particular meridian. Someone even ten feet away will have a different
LMT (unless they are N/S on the same meridian).
True Track – The number of degrees between the direction of flight and True North, as measured clockwise from a
longitude line. Also known as True Course (TC).
Three ways to depart on a cross country:
1. Overhead departure.
2. Set heading.
3. Direct method.
Set Heading Point:
Use a point other than the airport. Useful because you can’t always predict traffic and active runways. Gives us the time
and distance we may need to get completely organized. Pick a point along the track within 15 miles of departure.
Direct Method:
Pilot turns to the heading and goes. Preferred departure method for commercial students. Assume this method for all
calculations on the written exam.
Overhead Method:
Climb to cruise altitude while circling over the departure aerodrome, then set appropriate heading while crossing over
the airport.

Check Points:
Before takeoff, study the map and circle/mark a log of prominent landmarks that can help pinpoint position. Set up
checkpoints for ground speed checks. Note distances between checkpoints and also remaining distance to destination.
Using Position Lines to obtain a fix:
1. Visualize drawing a line through the center of the heading indicator to the landmarks. 2. Draw
these heading lines on a map from the checkpoints.
3. Where these lines cross is your position.
Ground Speed Checks:
1. Before takeoff, find two prominent checkpoints and measure the distance between them. 2. While in flight,
use a stopwatch to get the time between the two checkpoints. Be sure to use the minutes and seconds to be as
accurate as possible.
3. Divide the time by distance to get a revised ground speed.
4. Use ground speed to calculate the remaining time.
True Track: Apply wind speed to get True Heading.
True Heading: Correction for variation to get Magnetic Heading, then for deviation to get Compass Heading.
A heading is something that we have corrected for the wind. A track/course is something that has NOT been corrected
for winds.
Always go from True to Magnetic to Compass, whether you are working with tracks or headings: True Track - Magnetic
Track - Compass Track
True Heading - Magnetic Heading - Compass Heading.
For cruising altitudes, you fly the compass heading, but for picking your altitude, you need to use a magnetic track.
WCA – Wind Correction Angle.
The Double Cross Chart, which looks similar to a tic-tac-toe board, is an effective way of figuring out
true/magnetic/compass tracks and headings.
Determining Drift with ten degree lines:
- It is a good idea to draw two lines from both the point of departure and the destination at a 10o angle on
either side of the track.
- This practice is very helpful in correcting for wind drift.
- They correct for upper winds, which cannot always be forecast accurately.
Diversion to an alternate aerodrome:
You need to be able to quickly estimate a new heading towards a new destination. Calculating magnetic heading,
distance to be traveled, and new estimated arrival time all require the same fundamental operations that were used before
the flight. Due to space/time limitations (and flying), the pilot must simplify the calculations. To draw the selected route
while in flight, do a rough freehand. The magnetic track can be calculated by using a compass rose from a VOR. The
distance may be calculated by latitude lines or by the 10-mile ticks along the original track. - If you have to divert, make
a decision to do it ASAP. Your decision may be influenced by fuel, convenience, or easiest navigation. Safety must be a
priority. Choose carefully when visibility is reduced or when a ceiling makes low altitude navigation necessary.
Reciprocal Track Diversion:
- Essentially, turn around and go back.
- A standard rate turn will take sixty seconds to do a 180 o turn.
- Remember to apply your wind correction in the opposite direction!
Low level navigation:
- Watch out for power lines, towers, and terrain.
- Keep a finger on the map.
- Fly and trust a constant heading.
Deduced/Dead Reckoning:
- Once you know what you’re supposed to be tracking across the ground, look at it and go. - Used a lot in
aviation’s early days, before charts or electronic navigation aids were available. - Based on time,
direction, distance only.
- Pilots must know magnetic heading, distance, and rough winds.
- Write down times for each checkpoint passed.
IAS – Read off the instrument.
CAS – Corrected for instrument/position errors.
TAS – Corrected for temperature/pressure (there is a chart in the POH).

One In Sixty Rule – If you fly one degree off course for 60 NM, then you end up 1 NM off course.
Opening Angle (OA) = (Distance off course / Distance flown) x 60.
Closing Angle (CA) = (Distance off course / Distance remaining) x 60.
Total Course Correction = OA + CA
Three methods of getting back on track:
Visual Alteration Method:
- Just fly whatever heading you feel like until you are at a point over your original intended track. At that point,
start flying again but include a correction that will offset the angle error you originally noticed.
Double Track Error:
- You must be good at timekeeping. Must write down your departure time.
- Take your angle error, double it, and fly that new heading for the same amount of time as your departure to
the start of the correction. This will put you back on track.
- Cut your course correction in half at this point.
Opening and Closing Angle:
- Works anywhere along the track.
- Will not re-intercept the track, as the new heading sends you directly to the destination. - This is the
one-in-sixty rule in disguise.
Pilotage – Flying to a destination by hedge shopping or sightseeing, ie. visual landmark references.
Air Position:
- The location of the aircraft after a period of time based only on the course (track) and TAS. - Would
be the same position as a no-wind, so ignore the effects of wind.
Solving for a course with winds:
- Using a wind triangle.
- E6B calculations.
- Flight computer.
Wind Triangle:
- Air Vector: Heading and TAS, dead reckoning position.
- Wind Vector: Wind velocity and direction, the fix.
- Ground Vector: Track and ground speed, air position.
E6B Flight Computer:
- Outer front ring: Speed & distance.
- Middle front ring: Minutes.
- Inner front ring: Hours.
- Left window: Air temperature.
- Right window: Density altitude (inner) and Pressure altitude (outer).
- Black “10” square: Unit index.
- Black “60” triangle: Speed index.
Changing values – You need to carefully watch the changing values of the numerical graduations. The decimal point can
be free floating.
The Calculator Site lets you calculate time & distance, short time & distance, fuel consumption, true airspeed, true
altitude, density altitude, and simple multiplication and division.
For short time and distance, remember to use the 36 “seconds” marker instead of the black triangle.
On the Wind side of the E6B:
- The center point represents the ground speed.
- The outer ring is the True Index.
- The inner ring is the Rotating Azimuth.
Sliding Grid:
- Represents part of a large graduated circle.
- Lines projecting from the center of the grid and radiating outward represent degrees right or left of the
centerline.
- Lines that form the arcs around the center of the circle represent the distance from the center and are labeled in
miles.
To determine the total effect of wind on a flight, the true course, true airspeed, and wind velocity must be known.
Altitudes:
- Pressure Altitude: What the altimeter reads when set to 29.92 and is correct for standard atmosphere.
- Density Altitude: Pressure altitude corrected for temperature. This number tells us how the aircraft will perform.
- True Altitude: Corrected for temperature compression errors. This number tells us how high we are.
Airspeeds:
1. Indicated: What you see on the dial.
2. Calibrated: Corrected for position errors.
3. True: Corrected for temperature and altitude.
EET – Estimated Elapsed Time
ETE – Estimated Time Enroute
ETA – Estimated Time of Arrival
Factors affecting the choice of route:
- Planning on the ground is better than doing it in the air.
- The most direct route is not always the best.
- You may need to go around water, high ground, or restricted areas.
- Weather and safety are major concerns.
- Remember that the cruising altitude orders start at 3000’ AGL.
- Make sure you have current charts.
Map Preparation:
 - Don’t block out important underlying details.
- Don’t use red lines if flying at night.
- Include 10o drift lines (from both directions if your trip will include a return component). - Mark
interval indicators at maybe five or ten mile intervals.
- Include check points for both navigation and foreground speed checks (should be within about 50 NM or
thirty minutes flight time in a small GA aircraft).
Do weight and balance reports for both takeoff and landing.
Commercial aircraft must have an approved Minimum Equipment List (MEL) in place.
Snag – A problem found with the aircraft, which gets recorded in the log book. The aircraft needs to remain
grounded until the snag is deferred or rectified by an AME.
Conversions:
1 US gallon = 3.78 liters
1 NM = 1.15 SM
1 meter = 3.28 feet
You need to understand how to refer to Cruise Performance Charts (from the POH) to get TAS, fuel burn, and brake
horsepower.
When calculating climb data, remember that you are probably not starting from sea level.
Emergency Locator Transmitters:
- Broadcast on 121.5, 243.0, and 406 MHz.
- The new ones are 406’s. Satellites don’t pick up 121.5 broadcasts anymore, although a 406 still broadcasts
on 121.5 MHz.
- Old ELT’s had a 25 mW signal, but the new 406’s have a 5 watt signal (much stronger). - If the 406 is GPS
enabled, it sends out a burst of data every fifty seconds including a serial number, latitude, and longitude.
- The 406 ELT’s are mandatory in all new/changed registrations subsequent to February 1st, 2009.
Types of ELT:
- A/AD: Automatic Ejection or Deployment.
- F/AF: Automatic Fixed.
- AP: Automatic Portable.
- W: Water Activated.
- S: Survival.
ELT’s are mandatory for any aircraft more than 25 NM from home base, except for gliders, balloons, airships, ultralights,
gyros, and commercial transports.
Testing an old style ELT:
- Only permitted during the first five minutes of any UTC hour, for no longer than five seconds. - Check
121.5 MHz before shutting down.
- An activated ELT may be strong enough to wash over other frequencies in the aircraft.
Testing a 406 ELT:
-Follow the manufacturer’s instructions. - Do not test for more than fifty seconds or JRCC
- Can have an on/off/reset switch in the cockpit. will interpret it as a real emergency.
- Monitored by COSPAS-SARSAT geo satellites.
Possible toggle switch settings on an ELT:
- OFF: Will not activate.
- ARM: Will activate upon high impact (4 G’s).
- ON: Transmitting.
You may encounter a variety of switches on ELT’s, with some switches having only two positions and some having
three. It’s also possible to have slightly different labeling, depending on the unit.
If you’re about to “crash” and have a cockpit switch, and you’re worried that it might not activate, you could always
activate it just a few seconds before impact, then if things go well and you don’t need assistance, you have about fifty
seconds to disarm it before SAR is activated.
If the ELT can be placed in a high and non-secluded location, SAR will be able to find it more easily. Also, during
winter, the battery will last longer if the ELT is kept warm.
If you have an accidental ELT activation, report it ASAP, including the time, location, and duration of transmission.
Electromagnetic Spectrum:
- Long wavelength = low frequency.
- Low frequency = low energy.
 - Aviation radio waves (in the MHz) have much lower frequencies than microwave (GHz), infrared (THz),
visible light, and above.
- LF is 10 KHz to 30 KHz.
- MF is from 30 KHz to 3 MHz.
- HF is from 3 MHz to 30 MHz.
- VHF is 30 MHz to 300 MHz.
- UHF is 300 MHz to 3000 MHz.
- AM radio broadcasts (600 KHz to 1.6 MHz) are in the MF frequency range.
- NDB’s are from 200-600 KHz, surrounded by a bunch of dots on the charts.
- HF is where the shortwave is located. HF is used mainly for long range air and ground communications,
including oceanic crossings and operations in the high north.
- FM radio is in a narrow segment of VHF.
- UHF is mostly used by the military/government, and also by DME equipment.
VHF Frequency Bands:
- TV: 50.00 to 88.00 MHz.
- FM Radio: 88.1 to 107.9 MHz.
- VOR: 108.00 to 117.95 MHz.
- ILS: 108.10 to 111.95 MHz (overlaps a portion of the VOR range).
- Voice (aviation): 118 to 136 MHz.
Ground Waves – Radio waves that follow the surface of the Earth. Able to diffract or bend around obstacles, which
causes them to follow the curvature of the Earth.
Surface Attenuation – A method by which ground waves follow the curvature of the Earth. Think of the wave
interacting with the Earth and getting tilted downward.
Sky Waves:
- Can be reflected back to Earth by clouds and by the ionosphere, far past the reach of ground waves. - The
ionosphere will be higher at night, which means that reflected waves can reach much further. - Can be affected by
solar activity and other electromagnetic disturbances.
- Relatively free of atmospheric and precipitation static.
Skip Zone – an area on the earth where radio waves don’t reach, perhaps because it is too far from a station for ground
waves, but bouncing sky waves return to Earth past the zone.
LF/MF/HF – Can use both ground and sky wave frequencies.
VHF/UHF – Propagates almost exclusively as sky waves (line of sight).
Distance of Reception (in miles) = 1.23 multiplied by the square root of aircraft height in feet (AGL).
HF Single Side Band (SSB):
Normal AM signal has a carrier frequency and two sidebands, the upper and lower sidebands. In SSB, only one of the
sidebands is allowed to be transmitted, and the other sideband and carrier are suppressed. Once the signal gets to the
receiver, the carrier can then be re-inserted. Saves a huge amount of power because transmission of just one sideband
takes only about one sixth of the regular full signal (the carrier alone takes two-thirds of the power). Consumes narrower
bandwidth, only 3 KHz instead of 9 KHz normal, conserving spectrum space. Eliminates most of the transmission noise.
Automatic Direction Finding (ADF):
Greater range than VOR’s, which are line of sight. Being phased out very slowly. Low cost of installation, relatively
low maintenance costs. NDB’s and ADF’s are parts of the same system. The NDB sends out the signal, which is received
by the ADF. NDB signal has a significant ground wave component, following the curvature of the Earth, allowing
reception at low altitudes and over great distances. Most ADF’s can also receive AM. Type L is up to 50 watts, Type M is
between 50 and 2000 watts, and Type H is at least 2000 watts (low/medium/high).Limitations of NDB’s include errors
due to night effect, mountains, shorelines, electrical storms, bank error, ore deposits, fading effect, and two-station
interference.
Night Effect:
Radio waves are reflected by the ionosphere and they return to Earth thirty to sixty miles from the station. As the sun
rises or sets, the ionosphere will change its position in terms of height above the earth. This can cause the direction of
the NDB to appear to change as the reflection angle changes, and it may also cause the ADF pointer to fluctuate. This
effect is greatest within one hour of sunset or sunrise, at distances greater than thirty miles from the station. To
mitigate, fly at a higher altitude or select a station with a lower frequency. Frequencies under 350 kHz have very little
twilight effect.
Mountains:
 - Can reflect radio waves.
- Magnetic deposits in slopes may cause indefinite indications.
- Pilots should only use strong stations that give definite directional indications, and should not use stations
obstructed by mountains.
Shorelines:
- Can refract or bend low frequency radio waves as they pass from the land to water. - A pilot flying over water
should not use an NDB signal that crosses over the shoreline to the aircraft at an angle of less than 30o.
- The shoreline has little or no effect on radio waves that reach the aircraft at angles that are greater than 30o.
Electrical Storm:
- ADF needle points to the source of lightning because lightning sends out radio waves. - Pilots
should note lightning flashes and not use the indications caused by them.
- Lightning causes the greatest NDB errors.
Precipitation Static:
- Heavy precipitation may cause static when using low and medium frequencies. - NDB’s
are more susceptible than VOR’s.
Bank Error:
- ADF is subject to errors when the aircraft is placed into a banked attitude, due to the way that the antenna is
mounted. This is a significant factor during NDB approaches. Also known as dip error.
Fading Effect:
- Occurs when ground and sky waves interact, going in and out of phase, causing signals to be either canceled or
reinforced as the atmosphere changes.
- You’ll see a rhythmic swinging of the needle and a volume fluctuation of the identifier. - Most
common at night.
Two-Station Interference:
- Caused by congestion in LF/MF bands, when an aircraft can receive signals from two separate NDB’s on the
same or similar frequencies simultaneously.
- Essentially, this is a phasing error.
- May be more of a problem at night with increased transmission distances.
Relative Bearing – The direction of something (such as an NDB) relative to the nose of the aircraft. It is not a track or
heading!
Tuning:
After tuning the receiver, you must positively identify the station (you should hear a continuous two or three-unit
identification in Morse code). LF/MF beacons transmit a signal with 1020 Hz keyed to provide continuous ID except
during voice communications. If you don’t hear the Morse code, don’t use the NDB as the rest of the signal may be
corrupt. Use “receive” mode when tuning. After you receive the ident, go to “test” temporarily to check needle
deflection. Move to ADF settings for normal use. After a test, a sluggish return of the needle indicates a signal that is
too weak to use.The loop antenna is usually a small flat antenna with no moving parts, not an extension/protuberance
antenna. The loop antenna can’t tell if we are to/from a station. The sense antenna does this. - ADF audio must always
be monitored since there is no system failure warning flag. - NDB’s are always green on a map (except on the low VNC,
where they are purple). VOR’s are black. - For IFR, during approach/missed/holding, one crew member must aurally
monitor beacon idents unless there are instruments that can warn of ADF receiver failure.
Bearing To Station (BTS) – The track to get to the beacon.
Bearing From Station (BFS) – The number of degrees from the station. The opposite of BTS by 180 o.
Magnetic Bearing – The angle formed by the intersection of a line drawn from the aircraft to the radio station and a line
drawn from the aircraft to magnetic north. Equals the relative bearing plus the magnetic heading.
Reciprocal Bearing – The opposite of magnetic bearing, add or subtract 180o from the magnetic bearing. Calculate it
when tracking outbound and when plotting fixes.
VOX – Shorthand for voice. Also fits with the acronym for Voice Operated Exchange. Homing to an NDB – Flying
straight at it.
Homing in Winds – The pilot must constantly change magnetic heading to stay on relative bearing of 0 o, which causes a
flight arc even though the bearing indicator remains pointed at zero (unless crosswind corrections are made).
Tracking to an NDB:
- Means that you fly straight to the station by correcting for winds.
- The pilot needs to identify it by using both the bearing indicator and heading indicator (different from VOR).
- Sensitivity increases as you get closer to the NDB.
Position Fix by ADF – Use two or more stations and the process of triangulation.
Remember on the exam that we use magnetic headings, but if an examiner asks for a position on a VNC chart, we have
to convert from True.
Time Check and Distance To Station:
1. Note the BFS and then turn 90o from the BFS.
2. Note the time in seconds required to cross a certain number of degrees bearing change. 3. Time to Station in
Minutes equals the time in seconds divided by the number of degrees changed. 4. Distance to Station = (TAS x
Time To Station) / 60.
VOR Navigation:
VHF Omnidirectional Range. Approximately 450 ground based stations in Canada, maintained by Nav Canada. Each
station broadcasts a unique Morse code identifier, three letters long. The VOR Indicator does NOT care about the heading
of your aircraft! You can fly in circles while remaining on the same VOR. Compass Rose on a chart shows magneticity.
Transmits between 108.0 MHz and 117.95 MHz. Precipitation, static and electrical storms are not an issue. A tracking
accuracy of plus or minus 1o is possible on a 1o radial. Line of sight only. If you’re losing the signal, try climbing.
There are only 160 frequencies and about 450 stations, so you sometimes pick up two signals simultaneously.
Airways:
The airway system is partially based on VOR’s. The aircraft’s VOR receiver receives an azimuth signal sent from the
station. This azimuth From the station is called a radial of the VOR. The reverse of this radial is the To radial, and is 180o
off. VOR radials are all magnetic. It is the source of the radial that gives it its name, regardless of which direction the
aircraft is going. - Two main components: the receiver, and the navigation indicator. If the VOR receiver and the VHF
communications radio are co-located in the same control unit, the radio is called a NAVCOM. The VOR navigation
indicator (VOR Head) gives the pilot the aircraft’s position relative to a specific radial. The course index is a small
triangle pointing to the selected radial. The CDI needle (track bar) helps determine if the aircraft’s track is lined up
properly. - The deflection indicators are spaced at 2o intervals. The Red Nav flag, if visible, is the unreliable signal or no
signal flag. The Omni Bearing Selector (OBS) knob allows us to choose various radials. The CDI has a 10 o spread from
center to either side when receiving a VOR signal.You need to steer in the direction of the CDI deflection to get back on
track.
Reference Line:
- When a track is selected, the position of another line is established, which is a reference line
perpendicular to the track arrow and intersecting it at the station.
- It divides the VOR reception area into two additional sectors.
- The VOR will temporarily display OFF when passing over this line, even if the crossing point is not over the
VOR. This is the Area Of Ambiguity.
Area Of Ambiguity – Occurs when an aircraft is on a radial 90o to the one that they have selected. It widens with
increasing distance from the station.
To determine a fix without DME, you can use two VOR stations, and triangulate (remember that a DME gives
distance and direction, so triangulation is not necessary):
1. Find a station and twist the OBS until you get a From indicator with the CDI centered. 2. Next,
do the same with a second station.
3. Triangulate your chart.
Testing a VOR:
1. VOT Test.
2. Self-test.
3. Apron Check Sign.
4. Dual VOR Check.
5. Geographical Reference Point.
VOT Test:
-Slowly being phased out. and show From.
- Stands for VOR Test Frequency, which you must - Set OBS to 180o. CDI must center to within +/- 4o
look up in the CFS. and show To.
- Set OBS to 360o. CDI must center to within +/- 4o - Check full-scale deflection both ways by
checking ten degrees from both sides
Apron check:
- Airport sign in a run-up area or somewhere on the apron.
- Taxi up beside the sign, follow directions, VOR should be within +/- 4 o.
Dual VOR check:
 - Works if your airplane has two VOR receivers.
- Tune both to the same station, select the same radial, they must agree to within +/- 4o.
Airborne Geographical:
- Fly over a landmark on a known and published radial, and note the indicated radial. -
-Must be +/- 6o, this is the only method that allows for greater than a four degree variance.
Time & Distance check to station – Uses exactly the same approach and formulas as with the NDB, except
using radials instead of degrees (the same thing).
Primary Surveillance Radar (PSR) does not require an interrogation. It displays reflected radio signals from
contacts, aircraft, and weather. Being phased out.
Secondary Surveillance Radar (SSR) requires a reply from a transponder (interrogation) to determine the
aircraft’s range. Does not locate weather. Much better range than the PSR.
Area Navigation (RNAV):
Can be defined as a method of navigation that permits aircraft operation on any desired course within the
coverage of the station referenced navigation. No airways required. Developed to provide more lateral freedom
and thus more complete use of available airspace. - Includes GPS as one possible system. Does not require a track
to/from any specific radio navigation aid. A route structure can be organized between any given departure and
arrival point to reduce flight distance and traffic separation.Aircraft can be flown into terminal areas on varied
pre-programmed arrival and departure paths to expedite traffic flow. Instrument approaches can be developed and
certified at certain airports, without local instrument landing aids at that airport. Types include Multiple
VOR/DME, GNSS (GPS), Inertial Navigation Systems (INS), or Inertial Reference Systems (IRS).
VOR/DME Method:
- The Track Line Computer (TLC) system is based on azimuth and distance information from a VORTAC. Also
called the Rho-Theta system.
- Pilot effectively moves or offsets the VORTAC to any desired location (if it is within reception range). - The
phantom station is created by setting the distance (Rho) and the bearing (Theta) of the waypoint from a VORTAC.
- Use a series of these phantom stations to make up an RNAV route.
- Disappearing due to the prevalence of GPS.
Inertial Navigation Systems:
Completely self-contained and independent of ground-based navigation aids. After being supplied with initial position
information, it is capable of updating with accurate displays of position, attitude, and heading. Can give track and
distance between two points, course error, ETA, ground speed, and wind information. Can provide guidance and steering
info. Works due to accelerometers and gyroscopes. System alignment before flight is important. Accuracy decays at about
1-2 NM/hr. Position updates can be implemented in flight.
Flight Management System:
An integrated system that uses navigation, atmospheric, and fuel flow data from several sensors to provide a centralized
control system for flight planning and for flight/fuel management. Controls vary widely between aircraft. Multi-sensor,
including DME, VOR, air data computer, and fuel flow sensors. May also incorporate INS, IRS, and GPS. Most are
approved for en route IFR.
Tactical Air Navigation (TACAN):
- Used primarily by the military, it works like a VOR/DME.
- Provides azimuth (radials) and slant distance (NM) from ground station.
- 126 UHF channels.
- Civilian pilots trying to tap into it will receive only DME. Any VOR radial info would be a false signal. Radar
Altimeter – Provides dependable, accurate altitude AGL.
Flight Director System:
- Electronically collects info from several sources.
- Includes a Horizontal Situation Indicator and an Attitude Director Indicator.
- Can be used with or without autopilot.
- Command bars placed over top of the attitude indicator. The pilot keeps them aligned.
Airborne Collision Avoidance Systems (ACAS) and Traffic Alert & Collision Avoidance Systems (TCAS) both receive
SSR equipped aircraft (transponders) and the computer calculates if there is a chance of a collision.
DF Steer – Directional assistance to an aircraft using radio. Essentially phased out in Canada now.
Global Navigation Satellite System (GNSS):
Up to 32 satellites in orbit. Satellites in polar orbits, circling Earth in just under 12 hours. GPS satellites are referred to
as NavStar. Need to triangulate from three satellites for two dimensions (latitude and longitude). Need a fourth satellite to
also get an altitude/elevation position fix.
- Advantages include: Point to point navigation, not affected by weather, unlimited range, very accurate,
economical, available 24/7.
Always verify the coordinates of a waypoint! Think it out, don’t just stare at the digits and let your eyes glaze over.
Maybe you can verify from a CFS or map chart. Do not rely solely on the GPS.
Orbit at 11,900 NM, six different orbital paths, each satellite transmitting on 1227.6 MHz and 1575.42 MHz.
Virtually no errors due to atmospheric distortion. Line of sight, so watch out for signal masking. Each GPS satellite
has four atomic clocks to ensure accuracy. There is a master control station in Colorado Springs that has the capability
to send corrections to satellites if errors are detected. Be aware that GPS gives true tracks and ground speeds (not
airspeed).
Differential GPS:
- Used to achieve the accuracy required for more demanding operations.
- Done by having a receiver on the ground at a precisely surveyed position.
- The data can be “corrected” with cross reference from the ground station.
- Two types: WAAS and LAAS.
Wide Area Augmentation System (WAAS):
- A network of ground-based reference stations create a correction signal which is sent to WAAS geostationary
satellites.
- Compatible devices receive the correction signal from the satellite and improve upon accuracy.
Local Area Augmentation System (LAAS):
- An all-weather aircraft landing system based on real-time differential correction of the GPS signal. - Local
reference receivers located around the airport send data to a central location at the airport. - This is the basis for a
correction message, which is transmitted to users via a VHF data link. - Aircraft’s receiver corrects GPS data
with this message, and an ILS-style precision approach display becomes available.
System Integrity – The ability of a system to warn a user when there is something wrong with it. If ILS detects a
malfunction, it shuts down, flags, and you have to do a missed approach.
RAIM – Receiver Autonomous Integrity Monitoring (an integrity assessment system). FDE – Fault Detection &
Exclusion.
Baro-Aiding – A type of GPS integrity augmentation that basically allows your GPS to use your static system to
provide a vertical reference and reduce the number of satellites required in a RAIM system.
A GPS installation must have prior approval before it can be used in IFR conditions (TSO C-129 Standard).
Handheld devices will not be approved.
Be careful when entering GPS coordinates. For example, CWYG (the airport) and WYG (the VOR for that
airport) seem like they should be the same, but they are listed at different coordinates. User entered waypoints are
the most common source of GPS error. Do not navigate solely with GPS!
Transponder:
A radio receiver/transmitter which will generate a reply signal upon proper interrogation, designed to reinforce a
surveillance radar signal. Consists of a controller, a receiver/transmitter, and a k-Band antenna that looks like an
inverted shark’s fin. The ground station is a rotating directional antenna (you’ll see a light blinking on the transponder
when the ground antenna rotates toward you and does an interrogation). Mode C has a pressure altimeter in it that
gives apparent elevation, ie. asks for identification and altitude. Mode A asks for identification only. Mode S also
incorporates a unique signature, so you don’t have to dial a specific transponder code. - You can tell you have Mode C
if you have an ALT setting.
Squawk – To operate the transponder on a specified code, or to activate certain modes or functions on the
transponder.
Squawk Ident – Push the IDENT button. Only do this if ATC requests it.
Stop Squawk – Turn off your transponder.
Transponder Codes:
1000: General IFR below 12,500’ ASL. 2000: General IFR above 12,500’ ASL.
1200: General VFR below 12,500’ ASL. 7500: Hijack.
1400: General VFR above 12,500’ ASL. 7600: Communications Failure.
7700: Emergency.
Grivation – The angle between north as indicated by a grid on a map and magnetic north at any point.
CHAPTER 5 - WEATHER & METEOROLOGY
Solar radiation is shortwave. It hits the earth and is reflected back as long wave radiation. Long waves are then absorbed
by water vapor as latent heat.
Rising warm air at the equator creates a low. It then travels to the poles where it cools and sinks, creating highs.
The atmosphere is thicker at the equator than at the poles.
Air flows from areas of high pressure to low pressure (wind). The strength of the wind depends mostly on the pressure
differential between the two areas, and partly on the temperature differential. The atmosphere consists of 78% nitrogen
(N2), 21% oxygen (O2), and 1% trace gasses.
Permanent trace gasses include Argon (A R), Neon (NE), Helium (HE), Hydrogen (H2), Krypton (KR), and Xenon (XE).
Variable trace gasses include carbon dioxide (CO2), ozone (O3), methane (CH4), sulfur dioxide (SO2), and water
vapor (H2O).
Atmospheric layers:
1. Troposphere: Up to 20,000 feet, although this height often varies significantly. Temperature decreases
with height, +20 oC to -70 oC.
2. Stratosphere: 20,000 to 160,000 feet. Temperature increases with height, -70 oC to zero. 3. Mesosphere:
160,000 to 280,000 feet. Temperature decreases with height, zero to -100 oC. 4. Thermosphere: 280,000 feet
(50 miles) up to 350 miles or 500 km. Temperature increases with height, -100 oC to over 1000oC.
5. Exosphere.
The transition zones found between the strata are where there is a change in the lapse rate. “Space” starts about 50
miles or 80 kilometers above the Earth’s surface (at the beginning of the thermosphere). This is a slightly vague
definition.
About 99% of the atmosphere is found within the first forty kilometers above the surface. Half of this is located within
the first 5km, in other words, more than half of the total volume of the atmosphere is found within the troposphere.
Lapse Rate – The temperature changes with height. The defined Standard Lapse Rate is 1.98oC per 1000’ (in the
troposphere).
Most “weather” takes place in the troposphere. About 99% of the water vapor in the atmosphere is found within the
troposphere.
Troposphere:
Means “region of mixing,” has vigorous air currents. Temperature and water vapor decrease rapidly with altitude.
Average temperature is -56oC. Although we defined the upper boundary of the troposphere to be around 20,000 feet, it
can actually be quite a bit higher, depending on the season and the location on earth. The height varies seasonally, and it
is higher in the summer than in the winter. The tropopause is the boundary layer between the troposphere and the
stratosphere above it.
Stratosphere:
Temperatures increase as altitude increases, up to zero. Because the air temperature increases, it does not permit
convection, so weather that transits through the tropopause cannot rise any further. This lack of convection has a
stabilizing effect on thunderstorms. The stratopause (formerly mesopeak) is the boundary layer between the stratosphere
and the mesosphere above it.
Mesosphere:
Temperature decreases as altitude increases. Concentrations of ozone and water vapor are negligible. The
chemical composition of gasses at any given altitude depends strongly on altitude. Gasses start to form into
layers according to their molecular mass, so lighter glasses settle at higher layers than heavier glasses.
The mesopause is the boundary layer between the mesosphere and the thermosphere above it.
Thermosphere:
The temperature increases significantly with the altitude, very rapidly. Temperatures can get well over 1000oC. These
temperatures are caused by intense solar radiation. This is the layer which hosts the northern lights. The thermopause is
the boundary layer between the thermosphere and the exosphere above it.
Exosphere:
Starts at about 500km. The upper boundary is undefined. Perhaps between 1,000 and 10,000km, depending on
whom you ask. Pressure is little more than a vacuum.
At an altitude of approximately 150km, you start to enter the altitude for satellites, and aerodynamic lift can no longer be
used for maintaining height.

Definition of Standard Atmosphere:

-At sea level. - Change of 1.98oC per 1000’ (the standard lapse
- +15oC. rate).
 - 29.92” Hg or 1013.25 millibars/hectopascals. - 1” drop in mercury per 1000’ increase.
- Dry air, no humidity.
Pressure measurements:
- Aviators use pressure of mercury (Hg) in inches.
- Meteorologists use millibars.
29.92” Hg = 1.0 atm = 101.325 kPa = 1013.25 mb
Station Pressure – The weight of air pushing down on a station, then the station “adds” an imaginary column of air
between the station and sea level, which translates the physical reading to a theoretical reading that estimates sea level
pressure at the station.
With respect to temperature, the average surface temperature of the station over the past twelve hours is what is used.
Isobars – Lines on a weather chart that connect areas of equal pressure. Isobars are correct for sea level pressure. The
standard is to have them 4 millibars apart. Widely spaced isobars mean a shallower pressure gradient and relatively light
winds.
The standard airflow tends to be counterclockwise/upwards/inward around a low pressure system, and
clockwise/down/outwards around a high pressure system.
Pressure Gradient – The change in pressure over a given distance.
Although warm air usually creates a low, and cool air usually creates a high, remember that you always have to think in
relative rather than absolute terms, in comparison to nearby air. Also, other factors can come into play.
Pressure Systems include highs, lows, troughs, ridges, and cols.
High Pressure Center:
Air is sinking. In the northern hemisphere, air rotates clockwise and gently flows outward and downward. Also known
as an anticyclone. Large blue “H” on a weather map. In general, it is a region of subsiding air. Suppresses the upward
motion that is needed to support the development of clouds and precipitation. Commonly associated with fair weather
and light winds. Can remain stationary for days at a time.
Low Pressure Center:
Rising air rotating counterclockwise. This flow tends to increase as you move toward the center of a low. Strong
inward and upward flow. Also known as a cyclone. On a weather map, it is a red “L”. Air rises and becomes less dense
as it rises. Rising motions favor the development of clouds and precipitation.
- Lows usually tend to move quickly, perhaps 500 miles/day in summer and 700 miles/day in winter.
Trough:
Elongated area of low pressure. Symbol is a long purple line. Likely to bring about a wind shift at the surface. A trough
can act like a weak front.
Ridge:
- Sawtooth pattern on a weather map, although it is quite rare.
- Area of elongated high pressure.
Col:
-A neutral region between two highs and two lows. - In the winter, expect fog.
- Weather at a col tends to be unsettled. - In the summer, expect showers and
thunderstorms.
Boyle’s Law – At a given pressure, warm air will take up a greater volume than cold air. This greater volume will
typically exert itself by moving vertically upwards.
On cold winter days, when flying IFR, we need to factor cold weather corrections into altitude calculations.
At a given altimeter setting, an airplane will be much closer to a ground obstacle in the winter than it would be in the
summer.
Turning the altimeter subscale down results in a lower altitude.
If you set the altimeter (on the ground) in the Kollsman window and it shows a difference of more than 75 feet from
aerodrome elevation, you need to re-calibrate it.
As you progress cross-country and keep adjusting your altimeter, try to always use a setting from a station within 100
miles of your position.
When flying towards a low, if maintaining what appears to be a constant altitude on the altimeter, the aircraft will
gradually descend unless an altimeter correction is made. From high to low, look out below!
The altimeter does not compensate for non-standard temperatures! If terrain or obstacle clearance is a factor, a
conservative higher altitude should be flown to ensure adequate clearance. “From hot to cold, don’t be bold, or you
won’t grow old.”
When the air temperature is above standard, density altitude will be higher than pressure altitude. Remember that
higher density altitude means “air is less dense,” so the aircraft will not perform as well at that higher temperature.
True altitude is our exact height above sea level. Cold temperatures cause the pressure level to compress. Our
indicated altitude must be corrected for temperatures, especially for IFR or obstacle clearance! Use the left
window in the E6B for calculations of true altitude.
Rule of thumb for True Altitude calculations:
Multiply temperature variation from ISA (15oC) by 4 feet per 1000.’
The two main ways that the atmosphere is heated are radiation (terrestrial, not solar) and convection. The atmosphere is
heated from the bottom up!
Variations in Heating:
- Diurnal variation: Day and night.
- Seasonal variation: Due to the axial tilt of the Earth. A shallow lighting angle in winter results in less heating, but
there is a steeper lighting angle in summer. Also, there are more hours of daylight in summer.
- Latitude: Closely related to seasonal variation, although of course this is a constant factor rather than a
cyclical one.
- Topography: Land absorbs radiation faster than water, and also releases heat more quickly at night. Items such as
vegetation, soil type, slope, and aspect can significantly affect the amount of heating.
Methods of Heat Transfer:
1. Convection: Air near a warm surface is heated, and rises due to its buoyancy. Different surfaces (water,
trees, and buildings) convect heat differently. Convection transports heat in the vertical sense quite
efficiently.
2. Advection: Air is carried from one region to another by wind. Air is then warmed by the surface below.
This moves heat laterally.
3. Conduction: Heats layers of air that are in immediate contact with the Earth’s surface. 4. Latent Heat: Heat
energy that is stored in water vapor. When water vapor rises and condenses, the heat in the water vapor is released
during condensation.
5. Compression: When a large parcel of air sinks, it is compressed. Pressure increases, and the
temperature increases.
6. Turbulent Mixing: Turbulence that is caused by friction between the air and ground will create eddies
with vertical components. This will allow warm air near the surface to be lofted into the atmosphere.
Atmospheric cooling causes things like clouds, fog, and precipitation. This can happen through radiation,
advection, and adiabatic cooling.
Radiation Cooling:
- After the sun sets, the surface continues to radiate heat.
- This causes the ground to cool, then air in contact with the ground is cooled through conduction (heat
passing from the air to the colder ground surface).
- Radiation cooling rarely has an effect beyond the first few thousand feet above the Earth’s surface.
Advection Cooling:
- Air is carried from a warm area to a cooler area.
Adiabatic Cooling:
- Rising air starts to expand, and this leads to cooling.
- This can happen near mountains, near fronts, and in areas with a lot of convection. - This cooling occurs at
different rates depending on whether the air is saturated (with humidity) or not.
- Unsaturated air will cool at the dry adiabatic rate of 3oC per 1000’.
- Once saturated, it cools at 1.5oC per 1000’.
- Air with some humidity, if not yet saturated, is still subject to the “dry” adiabatic rate.
Environmental Lapse Rate – This is the observed actual change in temperature with a change in altitude. This changes
over time and is not a constant value. It changes from day to day, and even throughout the day.
Inversion:
Occurs when temperature increases as altitude increases. Air is very stable. Acts as a barrier to vertical movement of air.
A common cause of surface based inversion is radiation cooling from the surface on cool nights. - During a low level
inversion, if the relative humidity is high, expect smooth air and poor visibility due to haze, fog, and stratus clouds.

Isotherm – A line on a chart connecting areas of equal temperature. Usually dashed. May be darker for an important
isotherm such as 0oC.
Isothermal Layers – When the temperature remains the same at different altitudes. Like an inversion, it gives rise to
very stable air.
Transpiration – Moisture (water vapor) that is released by plants.
Sublimation – When a substance changes directly from a solid to a gas. This is how dry ice and snow forms.
Deposition – When a substance changes directly from a gas to a solid. This is how hoar frost is formed.
Dew Point – The temperature that air must be cooled to in order to reach 100% saturation. Knowing the dew point
also gives us a measure of how much water the atmosphere is currently holding. When the temperature is close to
the dew point, humidity is high. Also, the higher the dew point, the greater the amount of moisture present.
As air warms up, it can hold more water vapor.
Relative Humidity – The percentage of saturation of a parcel of air at that given temperature. Adding moisture to
the air (by evaporation or sublimation) increases the relative humidity and the dew point.
An adiabatic parcel will not add or remove heat from the surrounding atmosphere. When such a parcel rises, it
expands and cools. When it sinks, it will be compressed and warm.
Adiabatic Lapse Rate – Theoretical, can be calculated. If a dry parcel of air does not mix with the surrounding air,
then it can be considered adiabatic.
Dry Adiabatic Lapse Rate (DALR) – 3oC per 1000’.
The change in dew point temperature:
- The dew point also falls as the column of unsaturated air rises.
- The decrease in dew point temperature is 0.5oC per 1000’.
- Therefore, in a rising parcel of unsaturated air, the temperature and dew point converge at a rate of 2.5oC per
1000’.
- Use this for calculations of cloud base.
Saturated Adiabatic Lapse Rate (SALR):
- Accounts for latent heat released as water condenses.
- Once air has cooled to the dew point and starts condensing, the air parcel cools more slowly because condensation
releases energy.
- 1.5oC per 1000’.
Freezing level in feet above cloud base:
Freezing Level = (1000 x Dew point) / 1.5
Note that the dew point changes with altitude. A new dew point must be calculated at the freezing level by decreasing the
surface dew point by 0.5oC per 1000’ AGL.
Steep lapse rates lead to instability.
Precipitation - Occurs when condensing water droplets become large and heavy enough to overcome lifting agents such
as fronts & updrafts.
Icing is worse near the top of a cumulus cloud.
Three types of rainfall:
Frontal Rainfall:
Also known as convergent or cyclonic rainfall. Caused by the convergence of two air masses (fronts). Warm front rainfall
tends to be steady. Cold front rainfall tends to be showery.
Relief Rainfall:
Also known as orographic rainfall. Warm moist air is forced to rise over an obstacle such as a mountain range. This
cooling causes condensation, forming clouds and rain. Most of the rain is on the windward side of the mountain.
Mountains will also cause air streams to converge and funnel through valleys. Rainfall totals will increase when
mountains are parallel to the coast.
Convectional Rainfall:
The ground surface is locally heated, adjacent air expands and rises, convection rainfall occurs. - This heating
occurs daily in summer. Large cumulonimbus clouds are likely to form. Rain cools the air as it falls, because
some of it evaporates as it falls.The unstable conditions, possibly helped by frontal or orographic uplift, force the
air to rise in a strong vertical updraft or chimney. The updraft is maintained by energy released through latent
heat as water vapor condenses then freezes. The top of the cloud is characterized by ice crystals in an anvil
shape. The top of the cloud is flattened by reaching the temperature at the troposphere. - When the ice crystals
and frozen water droplets (hail) become large enough they fall in a downdraft. - This downdraft reduces the
warm air supply to the “chimney” and will limit the lifetime of the storm. These storms are usually accompanied
by thunder and lightning.
- Ice crystals have a positive charge. Snow forms under the same conditions as rain except that the dew point
temperatures are below freezing so the vapor condenses straight to a solid (deposition).
Snow:
- Ice crystals will form if there are small particles present for them to form onto. These may aggregate to form
snowflakes.
- Since warm air holds more moisture than cold air, snowfalls are heaviest when the air temperature is just below
freezing.
Sleet:
- Starts off as ice/snow when upper air is below freezing.
- A lower air temperature as it is falling allows it to partially melt.
- Then it goes through another cold layer and refreezes before it hits the ground.
Freezing Rain:
- Droplets stay in liquid form as they fall but are very close to freezing.
- They then hit frozen objects or ground, and freeze on contact.
Hail:
- Frozen raindrops that are more than 5mm in diameter.
- Hail keeps circulating up and down through a frozen layer until it is heavy enough to punch
downwards, form a downdraft, and fall to the ground.
- Can occur anytime, but is most likely to occur during summer and in cold fronts. Stable
Air – A small change will be resisted and the system returns to its previous state.
Unstable Air – A small change initiates a bigger change, and so on. Lifting actions in the atmosphere
decrease stability.
A rising (isolated) adiabatic parcel of air can only cool at one of two rates:
- Dry (unsaturated) adiabatic rate: 3oC per 1000’
- Saturated (wet) adiabatic rate: 1.5oC per 1000’.
Stable Air:
-Smooth flying. - Steady precipitation.
- Poor visibility. - Layer cloud (stratus).
- Ultimately ends in fog.
Unstable Air:
-Bumpy flying. - Cumulus cloud.
- Good visibility. - Ultimately ends in a thunderstorm.
- Showery precipitation.
If the layers of air closest to the surface are cooled, we increase the stability of the atmosphere. This can happen by
radiation at night, or by influx of cold air (cold advection).
Stability can also be increased by warming air at higher altitudes:
- Radiation cooling.
- Warm advection aloft.
- Large scale sinking of air.
Subsidence Inversion:
Air mass sinks and compresses. Upper part of the layer sinks/compresses more (relatively) than the bottom. Upper part
therefore increases in temperature more than the air at the bottom. Common in winter.
Things that enhance unstable conditions:
Daytime radiation. Warm air moving into a region (surface warm advection). Surface cold advection also. If cold air is
warmed by a warm surface, then it emulates the same behavior as if it had been warm air advection. Effects are enhanced
if there is moist air near the ground, and dry air aloft.
Dark earth absorbs more heat (solar radiation) than lightly colored earth.
Cooling of the upper atmosphere:
- Also causes instability, If cold air moves into higher altitudes and causes temperatures to cool faster than at the
surface.
Different lapse rates:
- Steep: Temperature decreases rapidly with altitude (leads to instability).
- Shallow: Temperature decreases slowly with altitude, fairly stable.
- Inversion: Temperature increases with altitude, stable.
- Isothermal layer: Temperature stays constant, stable.
If the environmental lapse rate is less than the DALR or the SALR, stability is favored. In this case, a parcel of air that
attempts to rise will end up cooler than the air around it.
Ways to cause heating of air near surface:
- Radiation: Long wave from ground.
- Conduction: Warm air contacting cold.
- Advection: Horizontal movement of air.
- Convection: Unequal surface heating.
Lifting processes that can cause instability:
- Convection: This happens due to unequal surface heating.
- Convergence: Excess air rises as pressure systems meet.
- Mechanical Turbulence: Surface friction.
- Orographic Lift: Air moving up hills/mountains (anabatic/katabatic).
- Frontal Lift: Advancing air being pushed up by cold air on the bottom.
Four types of stability:
- Absolute Stability: DALR and SALR are steeper than ELR.
- Conditional Stability: ELR is between DALR and SALR.
- Absolute Instability: ELR is steeper than both the DALR and SALR.
- Potential Instability: Instability would depend on some sort of a trigger mechanism, such as lift. An example
would be when the air is initially stable and unsaturated, but after becoming saturated, the lapse rate changes
and “adds” heat. This situation somewhat resembles conditional instability. Another scenario would be an
ELR that becomes steeper with altitude.
Layers of the sun:
- Photosphere (main mass).
- Chromosphere (similar to Earth’s atmosphere).
- Corona (all the stuff well above the surface).
Solar Wind – Charged atomic particles coming from the corona, moving quickly enough to escape the sun’s gravity.
These solar particles interact with the Earth’s magnetic field and with other particles in the upper atmosphere (aurora
borealis or aurora australis).
Sunspots:
- Operates on an eleven year cycle (but varies from nine to fourteen years).
- Tied to the sun’s periodic/variable energy output.
Solar Flare:
- Occurs when the area above a sunspot brightens and releases huge amounts of energy in the forms of ultraviolet,
x-ray, and radio electromagnetic radiation, and high speed solar particles. Can yield spectacular auroras, interfere
with radio and television reception, and knock out satellites and power grids.
Earth’s axis is tilted at 23.5o with respect to Earth’s orbital motion.
The equator is equidistant from each pole at every point along the equator.
Summer Solstice – Has the most hours of daylight of any day of the year, usually around June 21st. Winter Solstice –
Has the least hours of daylight, usually around December 21st.
Equinox – There are two of them, usually around March 21st and September 21st. On these two days, the sun is directly
“over” the equator. Spring is the vernal equinox, and fall is the autumnal equinox.
At the two solstices, the sun is above 23.5o latitude. One of the poles will experience 24 hour daylight, and the opposite
will experience 24 hour darkness (this 24 hour darkness/light actually lasts for several days).
Atmospheric Scattering – As sunlight and radiation passes through the atmosphere, particles of gas and dust are able to
scatter it. At the equator, there is not much scattering, as light and radiation passes straight through the atmosphere’s
normal depth. However, light and radiation reaching the poles does so obliquely, passing through the equivalent depth of
many atmospheres.
Cloud – A visible aggregate of tiny water droplets and/or ice crystals. Air must be saturated for clouds to form.
Air can be saturated in three ways:
1. By lowering the air temperature to the dew point temperature.
2. By adding water vapor into the air.
3. By mixing warm moist air to cold air.

Steam Fog – When you have a parcel of air that has some water vapor, and you evaporate more water into it, that
becomes a clouds
Okta – One eighth of the celestial dome. SKC: Clear sky.
 FEW: 1/8th or 2/8th. BKN: 5/8th to 7/8th, broken.
th th
SCT: 3/8 or 4/8 , scattered. OVC: Overcast, 8/8th, completely covered.
Ceiling:
Occurs with BKN or OVC, ie. more than half. VFR pilots are not allowed to fly over BKN or OVC, unless you have a
VFR OTT rating. - Ceiling is VV, vertical visibility, on the TAF or METAR. Example: VV003 = 300 feet. Has a scalloped
border on the GFA.
Clouds are classified into four families based on altitude and vertical development/appearance: - High: Above 20,000
feet, with a top usually around FL400 in Canada but it can be higher in other parts of the world. Includes cirrus,
cirrocumulus, cirrostratus.
- Middle: From 6,500’ to 20,000’, includes altostratus, altocumulus.
- Low: Below 6,500’, includes stratus, cumulus, stratocumulus, nimbostratus, stratus fractus, and cumulus
fractus.
- Vertical Development: Pass through two or all three of the above categories, including cumulus,
altocumulus, towering cumulus, and cumulonimbus.
Cumulus clouds are always puffy or pillowy, and often feature showery/inconstant precipitation. Cumulus clouds
frequently have roughly the same diameter, no matter what their altitude.
Stratus clouds are flat clouds that feature constant precipitation.
Nimbo clouds generate rain.
Cirrus (CI):
High and wispy. Generally above 20,000’. Sometimes called mares’ tails. Made of ice crystals. Generally appear in high
pressure systems, warm weather, and ahead of warm fronts. - Point in the direction of air movement at their elevation.
Cirrostratus (CS):
Really good at producing halos. Sheet-like, high level, composed of ice crystals. Tend to thicken as a
warm front approaches, signifying an increased production of ice crystals.
Cirrocumulus (CC):
Appear as a white sheet with a pebbly pattern. Somewhat rare.
Altocumulus (AC):
Puffy, cotton ball. On a warm, humid summer morning, they may be followed by thunderstorms as the day progresses.
Altostratus (AS):
Layer cloud with no definite pattern. Steely or bluish in color. Sometimes the sun or moon can be seen dimly throughout.
Seems to make the sun look like it is behind heavily frosted glass.
Stratus (ST):
Low layer cloud. Resembles fog but does not rest on the ground. No waves or patterns, gray.
Alto Cumulus Castellanus (ACC):
Created from instability associated with air flows having marked vertical shear and weak thermal stratification. Can
produce heavy precipitation.
Nimbostratus (NS):
Dark, low level clouds accompanied by light to moderate precipitation. Mostly water droplets, not ice crystals.
Stratocumulus (SC):
Low, lumpy layer of clouds. Sometimes accompanied by weak intensity precipitation. Stratocumulus on the windward
side of a mountain range may be supercooled and may lead to icing.
Stratus Fractus (SF):
Stratus cloud that has been torn by wind into fragments. May release drizzle.
Cumulus Fractus (CF):
Stratocumulus torn by wind. Can be differentiated from stratus fractus by their more rounded tops.
Cumulus (CU):
Fair weather. Appearance of floating cotton. Have a lifetime of 5-40 minutes. Given suitable conditions, can develop into
towering cumulus and then cumulonimbus.
Towering Cumulus (TCU):
Growing cumulus clouds. On the way to becoming a cumulonimbus. Like a giant cauliflower in the sky.

Cumulonimbus (CB):
Much larger and more vertically developed than fair weather cumulus. Fuelled by vigorous convective updrafts that are
at times in excess of fifty knots.Depending on the height of the troposphere and the buoyancy of the updraft, the tops of
cumulonimbus clouds can reach up to 60,000’.
Mammatus:
Powerful cumulonimbus clouds that may have appendages protruding from the base. Indicate that the
atmosphere is extremely unstable. Severe weather is possibly imminent.
Mountain Wave Clouds:
- Top: Moist layer of air, lenticular clouds.
- Middle: Dry layer of air.
- Bottom: Cap cloud, rotor clouds.
Orographic Clouds - Associated with mountains, develop when air is forced to rise by the Earth’s topography. This can
happen either prior to encountering a ridge, or after.
Lenticular Clouds – Form in the wave crest, very high and hundreds of miles long. Can look like a tortoise shell or like
a stack of pancakes.
Rotor Clouds (roll clouds) – Form downward and below each wave crest. They are dissipating and forming at the same
time due to the rotation of air.
Cap Cloud – Lie over the top of the mountain and extend partially down the leeward slopes, indicating an extremely
strong downdraft.
Contrails:
Cloud formed by the water vapor contained in the exhaust of jet engines. At high enough altitudes, the vapor turns
immediately to ice crystals. Resemble a long thin line of cirrus.
Mountain Waves:
Oscillations on the lee (downward) side of a mountain caused by disturbances in the horizontal air flow due to the
impending terrain. Can have speeds in excess of 5000 feet/second. About 150 NM in length is common, and can be
much longer. Most severe near the mountain or mountain ridges, and at about the same height as the top of the
summit. Significant horizontal and vertical shear may exist. Average wave length is 8 NM. A standing mountain wave
is fairly stationary as it propagates horizontally.
Conditions conducive to forming a mountain wave:
-Wind direction must be within 30o perpendicular to - Winds aloft increase with height.
the mountains. - Stable air mass layer aloft or an isothermal layer
- Wind velocity on the leeward side must be 25 or inversion near the mountain top.
knots or more.
Factors affecting wavelength:
-Stability: Higher stability makes shorter - Lateral Positioning of Ridges: Ridge spacing can
wavelengths. also change the wavelength.
- Wind Speed: Higher wind speed equals longer - Ridges will need to be 5km apart.
wavelengths.
Amplitude:
Half the vertical distance from the wave trough to the crest. Varies with height above the ground. Smaller amplitudes
near the surface and near the tropopause. Larger amplitudes between 3000’ to 6000’ above the ridge. Generally, the
greater the amplitude, the shorter the wavelength.
Factors affecting amplitude:
Lower stability produces lower amplitudes. Larger mountains produce greater amplitudes. Ridges with widths similar to
typically formed wavelengths will produce greater amplitudes. - A sharp lee slope will produce greater amplitudes.
Drops of greater than 3,000’ tend to produce the largest amplitudes.
There must be sufficient moisture for clouds to form, so lack of clouds does not always mean that it will not be turbulent.
Clouds that might indicate the formation of mountain waves include lenticular, rotor, cap, and banner.
Lenticular clouds:
Typically from 20,000’ to 40,000’. As the air in a mountain wave rises, it cools by expansion and condenses out moisture
to form the leading edge of the lenticular cloud. After air flows over the crest, it continues downward. Due to
compression, the moisture evaporates and is absorbed. The associated winds extend to the troposphere, making it difficult
to avoid by simply flying over it. - Lenticulars form in the crests of waves, and can be hundreds of miles long. In a PIREP
or METAR, it will be reported as either Alto Cumulus Standing Lenticular (ACSL) or Cirrocumulus Standing Lenticular
(CCSL). Cirro means ice crystals.

Rotor Clouds:
Indicate the presence of mountain waves. Possess the greatest amounts of turbulence. Avoid flying through, between, or
below rotors! Will form downward from each wave crest, land within the lower turbulent zone. Can be dissipating and
forming at the same time due to the rotation of the air. Diameter between 600’ and two miles. Center of rotation typically
near the ridgeline. The first rotor will be the most intense.
If you must pass through an area with rotors, the best choice is above them, and the second best option is around them.
Never fly under them if there is any alternative at all.
When flying downward into mountain wave turbulence, your aircraft will hit the turbulence faster and more violently.
Configure the aircraft for turbulence penetration.
Altimeter effects from a mountain wave:
- The drop in pressure associated with an increase in wind speeds will cause the altimeter to read incorrectly.
- This, coupled with non-standard temperatures, may result in an altimeter over-reading by as much as 3,000’ feet.
Four types of winds in mountain terrain include anabatic, katabatic, glacier winds, and funneling.
Anabatic:
Formed as the sunward side of a mountain slope heats up. Warm air starts to rise up the slope, creating an upwards flow
on the mountain. Pockets of turbulence are possible as the mountain slope heats up at different rates.
Katabatic:
Flows downslope. Can happen in areas that are shaded, although they are typically more powerful at night when
radiation cooling starts to happen. Wind will then flow down mountain valleys.
Glacier Wind:
Extreme type of katabatic wind. Cools over the glacier, starts to rush downhill, sometimes faster than 80 knots.
Funneling:
Flows perhaps between two ridges, or around a single peak. Speeds up, pressure drops abnormally. Very dangerous.
To limit exposure to mountain winds:
When crossing ridges from downwind, do it at a 45o angle and with a minimum clearance of 3000’ when strong
winds are present. If caught in a downdraft, speed up to get out of it rather than pitching for V Y to attempt to
outperform it. Check AIRMETs and PIREPs.
Types of Turbulence:
Convective Turbulence:
Caused by uneven heating of the earth’s surface. Darker areas such as soil, rocks, or sand heat up faster than lighter
areas such as grass or water. - Warm air will rise and be replaced by cooler sinking air. Indications include fair weather
cumulus, TCU’s, ACC’s, and CB’s. If possible, fly above clouds to avoid convective turbulence.
Mechanical Turbulence:
Caused by friction between air and ground. Created when wind encounters terrain like trees, or man-made
objects/buildings. - The GFA shows heights that MECH will be based at, along with maximum height. - From the surface,
it usually extends to between 2000’ and 5000’ AGL. Only shown on forecast if expected to be moderate or worse.
Frontal Turbulence:
Caused by friction between two opposing air masses. More commonly associated with cold fronts than with warm
fronts, although it can be either.
Orographic Turbulence:
Caused by friction in air currents through mountainous regions. Airplanes approaching hills or mountains from the
windward side are helped by rising currents. - Aircraft approaching from the leeward side encounter descending currents.
Mountain Wave Turbulence:
The fact that mountain waves are stationary means that the effects of turbulence on an aircraft are different when
flying downwind than when flying upwind.
Shear Turbulence:
Also known as wind shear. A change in wind speed and/or wind direction in a short distance. Can exist in a horizontal or
vertical direction. The greater the speed/direction change, the greater the severity. Some forms include microbursts and
virga.
Low Level Wind Shear:
There are six different types: Microbursts, virga, rotor winds, low level nocturnal inversions, low level jets, and
funnel winds. Can present a significant hazard to aircraft during takeoff/landing/climbing/descent. - Defined as a
significant, non-convective wind shear that could adversely affect aircraft operation within 1500’ over an
aerodrome. On the TAF/METAR, the height of the top is given first, followed by wind speed and direction at that
height. To a large extent, wind shear is an element that cannot be satisfactorily observed from the ground. Aircraft
reports and radiosonde reports are often the only ways that we can determine its possible presence. The main effect
is rapid gain/loss of airspeed. On a chart, WS indicates strong non-convective low-level wind shear expected within
1500’ AGL.
Wind shear reporting guidelines:
 - Change in wind speed of greater than 25 knots within 500’ AGL.
- Change in wind speed of greater than 40 knots within 1000’ AGL.
- Change in wind speed of greater than 50 knots within 1500’ AGL.
- Pilot reporting gain or loss of indicated airspeed of greater than 20 knots within 1500’ AGL.
Radiosonde – A battery-powered telemetry instrument package/probe carried into the atmosphere (usually by a weather
balloon), which measures various atmospheric parameters and transmits them by radio to a ground receiver.
Low Level Jets:
Often associated with a frontal system. A powerful jet of air following a front can produce significant turbulence.
Represented by a double-line black arrow on the charts.
Nocturnal Inversion: As night falls, winds aloft become decoupled with surface winds.
Microbursts: Formed by cold dense air and rain shafts as they rapidly descend.
Virga:
Similar to a microburst. Rain that falls, dragging cold dense air along with it. Should this rain fall into a layer of drier air
below, it will evaporate. The cold air that was falling with it will continue downwards, but without any rain that would be
a visual indicator of a strong downdraft.
Funnel Winds: Gently blowing winds can be forced into valleys, where they will speed up and create an area of
shear.
Clear Air turbulence (CAT):
Frequently associated with a jet stream aloft. Can also be caused by a sharp temperature gradient, mountain waves, or
wind profiles that vary significantly.
Turbulence Reporting:
- Light: Slight changes in attitude/altitude.
- Moderate: Greater intensity, aircraft under control.
- Severe: Large abrupt changes, temporarily out of control.
- Extreme: Airplanes are violently tossed, control is impossible.
- Chop: Intermittent turbulence.
The Coriolis force always makes things appear (to an observer in the northern hemisphere) to curve to the right.
In the upper troposphere, the air is unaffected by friction and we can see that there is a balance between the Pressure
Gradient Force and the Coriolis force.
Resultant Wind – Thanks to the balance between the pressure gradient wind and the Coriolis force, the geostrophic
wind blows parallel to the isobars. However, it is also slightly modified by friction from the surface which reduces the
Coriolis force and causes the wind to blow at a slight angle to the isobars.
Buys Ballot’s Law:
If you stand with your back to the wind (in the northern hemisphere), the low is always on the left and the high is
always on the right. Determining the highs and lows tells you the direction that the pressure gradient wind is blowing.
- Coriolis force is always in the opposite direction to the pressure gradient force.
Tri-Cellular Model:
Warm air rising at the equator, then moving to the poles and sinking, is just one aspect to consider. The earth’s
rotation, uneven distribution of its land masses, and the oceans all play a part in air circulation. This all means that
there is more than one cell responsible for recirculating the air through the atmosphere.
Latitude Regions:
- Polar: From 60o latitude to the poles, known as the polar cell, easterly winds.
- Mid Latitude: From 30o to 60o latitude, known as the Ferrel cell, warm southwesterlies.
- Tropical: From the equator to 30o, known as the Hadley cell, northeast trade winds.
There is generally HIGH pressure at the Poles and at 30o latitudes.
There is generally LOW pressure at the Equator and at 60o latitudes.
Doldrums – Low pressure, light wind area near the equator.
The equator is also known as the Inter Tropical Convergence Zone (ITCZ).
The areas at 30o latitude (which are generally high pressure areas) usually have clear skies and stable conditions.
The areas at 60o latitude (called the polar front) usually have low pressure, unstable conditions, and cyclonic rainfall.
Veering: Wind direction changing clockwise.
Backing: Wind direction changing counter-clockwise.
A calm ocean surface is smooth and has little effect on the wind. A city has a great effect on the wind speed and
direction.
Winds usually veer and increase during a climb out, and usually back and decrease during an approach. This is just the
way things generally work when you’re changing altitude. Non-standard winds frequently indicate warm fronts.
Gust – A brief rapid change of wind direction and/or speed.
Squall – A prolonged change of wind direction and/or speed. Be careful, as another separate definition of a squall is a
long line of thunderstorms.
Diurnal Effects:
During the day, vertical currents are formed that link the upper and lower winds, making them similar. At night,
a nocturnal inversion develops and there is no link between upper and lower surface winds; they back and
decrease. There can be a large difference between upper and lower winds. Winds at the surface can be stronger
and gustier during the day.
Sea Breezes:
A high develops over water (in the day) and a low over land. Air flows from highs to lows, ie. a cool breeze will be
coming off the ocean towards the land (during the day). The reverse (a land breeze) happens at night, with winds blowing
out to the ocean.
Types of Wind Shear:
1. Speed: Wind is blowing at different speeds at different altitudes.
2. Directional: Wind is blowing in different directions at different altitudes.
3. Increased Performance: An increasing headwind or decreasing tailwind.
4. Decreased Performance: A decreasing headwind or increasing tailwind.
Rossby Waves – Very strong winds in the upper troposphere, organized into wave patterns. They are the result of
temperature variations and the rotation of the earth. Depending on the season and circulation, there can be anywhere
from three to seven existing at any given time.
Jet Streams:
-Blow in excess of 230 km/hr. world within a week.
- Rapid transfer of energy around the globe. - Usually at least 60 knots.
- Can distribute debris from eruptions around the
Main Jet Streams:
- Polar Front (PFJS): From about 40o to about 60o latitude.
- Subtropical (STJS): At around 25 o to 30o latitude.
- Easterly Equatorial (EEJS): At the equator.
Polar Front jet stream (PFTS):
When it moves south, it brings cold air, which gives us dry and stable conditions with high pressures. When warmed, it
moves northward, giving strong winds and heavy rainfall. As winter approaches, it becomes stronger and plunges far to
the south. The wind speed is greater in winter, due to large temperature differences between the Polar and Ferrel cells.
During summer, it moves northward and wind speeds usually decrease.
Subtropical (STJS):
Found on the boundary between the Ferrel and Hadley cells. Weaker than the polar front jet stream due to lower
temperature variations between cells.
Easterly Equatorial jet stream (EEJS):
Tends to form aloft along the ITCZ (equator). Fairly seasonal, associated with summer monsoons in India.
Gentle jet stream.
Air Mass:
A large body of air (usually at least 1000 miles across) that has similar properties of temperature and moisture
throughout. The most likely source region is a large flat area where air can be stagnant long enough to take on the
characteristics of the surface below. The source region is always an area of high pressure. Slowly moving highs are the
best. Wind varies little with height. Usually named based on temperature and humidity, which of course is determined
by the source region. The name will be two parts, with the first part identifying the moisture region and the second part
identifying the temperature region.
Moisture Regions: Continental (dry) or maritime (moist).
Temperature Regions: Arctic (coldest), polar (mid-temp), or tropical (warmest).
Canada doesn’t have many continental-polar air masses because we’re actually a source for them. We don’t have many
continental-tropical air masses either. That leaves CA, MA, MP, MT: Continental Arctic, Maritime Arctic, Maritime
Polar, and Maritime Tropical.
Air masses are generally modified by either warming or cooling from below:
- An air mass being warmed from below results in instability and convection.
- An air mass being cooled from below results in an inversion and stability.
Fronts cause abrupt changes in temperature, wind, and stability.
Frontal weather is determined by:
- Stability and moisture content of warm air.
- Speed of cold air.
- The slope.
A front is named after the advancing air mass.
Symbols for fronts on maps: Warm fronts are red semi-circles, cold fronts are blue triangles, and occluded fronts are a
mix of each.
Types of fronts:
Cold Front:
Transition zone where cold air is replacing warmth. Tends to move more quickly than a warm front. Tends to undercut a
warm air mass. Tends to produce CU, CB, and TCU clouds. Isobars make a V-shape in the vicinity of the front. Maybe
500 miles wide.
Warm Front:
Warm air mass replacing cold. Slower than a cold front, overrides cold air. Slopes are very shallow, typically one half of
one degree.Maybe 200-250 miles wide.
Occluded Front:
When a cold front associated with a low “catches up” to the warm front, overtaking and undercutting it.
Does a wrap-around, disconnecting the warm air from the surface. Usually shown on a weather chart as
alternating purple half circles and triangles.
Trowal:
Used in Canada as another name for an occlusion. Stands for “trough of warm air aloft.” Usually a blue
line with red quadrilaterals on a weather chart. Can vary significantly depending on moisture content of
warm air, ie. anything from dry to heavy precipitation. Generally resembles a warm front ahead of the
trowal, and a cold front trailing. - In relation to the associated low, maximum precipitation, icing, and
convective activity will typically be in the northeast sector.
At a trowal/occlusion, remember that there are three air masses present: cold air, cool partially mixed air, and warm
air.
Stationary Front:
Not moving, neither air mass is replacing the other. Noticeable temperature change and/or change in wind direction is
common when crossing from one side to the other. Winds will be blowing parallel to the front.
Frontogenesis – Occurs when the temperature gradient becomes sharper.
Frontolysis – A dissipating front.
Upper Fronts:
Can happen when air is trapped on the surface and the frontal weather is pushed aloft. There will be few
indications of the frontal passage to a ground observer. No wind shift and no temperature change. However,
precipitation is still likely to fall. Upper fronts have empty symbols on a weather chart.
Frontal Fog – Associated with weather fronts, particularly warm fronts. Caused when frontal precipitation falling into
the colder air ahead of the warm front causes the air to become saturated through evaporation.
With the passage of a cold front, the surface wind usually veers and increases with speed.
Airframe Ice – Forms when supercooled water droplets strike an airframe that is at a temperature of less than zero
degrees. The three main types are rime, clear, and mixed.
Rime Ice:
Likes to form in layered clouds, like stratus. Rough, milky, opaque. Lots of air pockets, like what you see when you
open your freezer. Freezes instantly.
Clear Ice:
Larger drops, may be cumuliform. Smooth and transparent. Hits the leading edges, does not freeze instantly. Flows a
bit, filling in cracks and pockets, then freezes. Larger accumulations are characterized by upper and lower horns.
Extremely dangerous.
Always do everything possible to stay out of freezing precipitation. It is one of the most dangerous things out there for
pilots.
Factors having an effect on the rate of ice accumulation:
1. Shape: Thinnest surfaces collect the most ice.
2. Speed: Higher airspeeds result in greater rates of ice accumulation.
3. Droplet size: Large droplets are more likely to strike the wing than a smaller droplet.
 Icing Intensity comes in four levels: trace, light, moderate, and severe.
Trace icing:
Ice becomes perceptible. The rate of accumulation is slightly greater than the rate of sublimation. Generally not
hazardous unless you’re in it for a while (well over an hour). There is no symbol on the weather charts for trace icing.
Light icing:
The rate of accumulation will create a problem if the flight is prolonged (over an hour). - There is no symbol on the
weather charts for light icing.
Moderate icing:
Even short encounters are potentially hazardous.Has a symbol on the weather charts. De-icing or anti-icing equipment
will be required to clear it, and a diversion may be necessary.
Severe icing:
The rate of accumulation is fast enough to render de-icing or anti-icing equipment useless. - An immediate
diversion is necessary.
When icing is encountered:
1. Make an immediate decision.
2. Climb, descend, or go back.
3. Activate de-icing or anti-icing equipment, if available.
4. Turn on pitot heat and cabin heat.
Dangers of icing:
1. Poor aerodynamics.
2. Increased drag and weight.
3. Decreased lift and thrust.
Effects:
Aircraft’s performance will decrease. Increase in drag caused by rough surfaces. Decrease in power due to intake
blockages. Engine failure due to carb icing or blocked air intake. Engine foreign object damage (FOD) is likely for
turbine engines. Ice alters the wing shape, you become a test pilot. The angle of attack decreases, perhaps low enough to
happen before the stall alarm sounds. - Deteriorating trim effectiveness. Asymmetric shuddering and vibrations if one
prop blade sheds ice. Control surfaces may freeze in place. Flaps can be damaged during extension/retraction.
Landing gear may freeze in place or be damaged. Fuel vents may become blocked, which can lead to fuel starvation.
Pitot tube blockages will lead to airspeed errors. Obscured cockpit visibility. Antenna problems, poor radio reception.
Bank angles greater than 5o can cause a stall.
How to deal with potential icing:
Consider climbing through ice more quickly, if you’re stuck in it. File a PIREP. On landing approach, use more power
and higher airspeed. Clear ice tends to form in cumuliform clouds, try to avoid them whatever the season. The worst icing
in these clouds is between -10oC and 0oC. Rime ice tends to form in stratiform clouds. Accumulation is greatest between
-10oC and -20oC.
De-Icing and Anti-Icing equipment:
- Balloons.
- Heaters.
- Jets may use bleed air from engines.
Weeping Wing systems (also known as TKS) may pump fluid through mesh screens on the leading edges of the
wing and tail.
Frost forms on the aircraft when the surface temperature of the aircraft is below the dew point and below 0oC.
Frost can reduce wing lift by 30% and increase drag by 40%.
Cold Soaking – Typical when an aircraft comes down from the flight levels (where it is cold) and into warmer air
below. Warm moist air will then condense and freeze as it comes into contact with the cold portions of the wings.
If you start losing power, impact ice may be causing a problem. Select carb heat or alternate heat. Lean the mixture if
carb heat is used continuously.
How to Avoid:
1. Stay out of clouds and visible moisture when the outside air temperature (OAT) is below freezing. 2. Fronts
and low pressure systems are often associated with clouds.
3. If you must fly through a front, do it directly instead of at an angle.
4. A warm winter front is terribly dangerous.
Carry extra fuel, in case a diversion is needed!
Tail Stall:
 Tail can collect ice a lot faster than the wing. Horizontal stabilizer produces a down force that keeps the nose up. If the
tail stalls due to excessive icing, we would have a sudden and violent pitching of the nose down. This would be preceded
by oscillations in the control column, as opposed to the sensation of wing buffeting.
Recognition of a Tail Stall:
Can lead to abnormal pitch forces when flaps are extended, so don’t extend. A buffeting may be felt in the control
column(s), instead of in the airframe. A pilot induced oscillation may be an early indication.
Recovery:
- Raise flaps to the previous setting immediately.
- Pull back on the yoke, and reduce power if altitude permits.
- Do not increase airspeed unless necessary to avoid a wing stall.
If you suspect tail icing:
-Approach at the proper speed for your - Keep small bank angles for turning.
configuration. - Avoid abrupt pitch-down movements and thrust
- Keep the flaps retracted. changes.
Hoar Frost:
Caused by cooling on clear/calm nights. The Dew point of surrounding air is below zero. Water vapor turns directly to
ice (deposition). Frost color is white and opaque. Melts quickly.
Thunderstorm Development Requirements:
- High moisture content.
- Steep lapse rate.
- A lifting agent.
Development Stages:
1. Cumulus/developing stage: Updraft dominated.
2. Mature stage: Updrafts and downdrafts.
3. Dissipating stage: Downdraft dominated.
Cumulus Stage:
Warm moist unstable air is forced to rise. Moisture rapidly cools into liquid drops of water due to the cooler
temperatures at high altitude, which appears as cumulus clouds. As this water vapor condenses into liquid, latent heat is
released. This warms the air, causing it to become less dense than the surrounding dry air. Upward growth rate of 5 to 20
m/s, which is 10 to 45 mph. The updraft holds all the water droplets and ice crystals, so the rain is unable to fall. -
Usually, there is no precipitation at this stage.
Mature Stage: (Air Mass Storm)
Warmed air continues to rise until it reaches existing air which is warmer, then the air can rise no further. This cap
is often the tropopause. Air is forced to spread out, giving it an anvil shape. Water droplets coalesce into larger and
heavier droplets and freeze into ice particles. As they fall, they melt into rain. The cloud may have already reached a
height of 60,000’ and the updraft may be traveling at more than 6,000 feet/minute. While updrafts are still present,
falling rain also creates downdrafts. There will be strong downdrafts in areas of the heaviest precipitation. The heavy
rain cools and drags down the air with it, at speeds of up to 2000’ per minute.
Precipitation/turbulence/thunder/lightning are at their most intense. Turbulence is high due to the opposite rushing
air currents at the middle level. Updrafts continue to dominate the inner portions. Most of the downdrafts form on
the outside edges. Typically lasts fifteen minutes, but can last for an hour.
Dissipative Stage:
As heavy precipitation falls through the cloud, the cloud cools, and then downdrafts dominate the base of the
cloud.
If atmospheric conditions do not support “supercell” or “squall” development, this stage occurs rather quickly.
The downdraft will push down out of the thunderstorm, hit the ground, and spread out, causing a microburst.
This cooling causes the cloud to lose energy and the rainfall gradually ceases. Cool air carried to the ground by the
downdrafts cuts off the inflow, so the updraft disappears and the thunderstorm will dissipate.
Methods of Lift that create thunderstorms:
1. Orographic (Air Mass thunderstorm) – Form in mountains, created as air moves up a steep slope. 2.
Convection (Air Mass thunderstorm) – Rising hot air creates the energy source. Often seen on a summer
afternoon. Can even be triggered by wildfires.
3. Frontal – Created by frontal lift. Fast moving cold fronts can create energetic storms (known as Steady
State thunderstorms).
Squall Line:
 A line of thunderstorms moving in unison. Frequently found well ahead of a fast moving cold front. Exercise extreme
caution when close. Leading edge will be where updrafts and downdrafts are most severe. If you have to pass through,
penetrate the lightest areas.
Do not mistake a shelf cloud for a tornado. This happens commonly.
Lightning:
Air has an electrical resistance. When the electric potential or difference is large enough to break down this resistance,
the electrons flow to the positive charge, forming lightning. There can be lightning from clouds to the air, to the ground,
or to other clouds. - The greatest likelihood of lightning hitting an aircraft is between -5oC and +5oC. Lightning can strike
an aircraft flying in clear air in the vicinity of a thunderstorm. - Lightning may or may not cause problems if it hits an
aircraft.
There is no useful correlation between the external visual appearance of a thunderstorm and the
severity or amount of turbulence or hail in it. The visible thunderstorm is just a portion of a
violent system of updrafts and downdrafts that often extend far beyond. Severe turbulence may
extend up to 20 NM from severe thunderstorms. No flight path through an area of strong or very
strong radar echoes that is separated by less than 40 NM can be considered to be free of severe
turbulence.
Engine Water Ingestion – The strength and velocity of updrafts in a thunderstorm are strong,
and heavy concentrations of water collect in clouds. This moisture may exceed the amount that a
turbine engine can ingest, and the engine can flame out, so turn on the igniters if you’re in a
turbine.
The pressure ahead of a thunderstorm falls rapidly, then rises abruptly after the rain starts.
Whenever possible, do not take off or land when a thunderstorm is approaching. They can have
gusts exceeding 50 KTS, and wind direction can reverse in seconds.
If flying over a thunderstorm, clear the top by at least 1000’ for each 10 knots of wind speed at
cloud top. Hurricane – A huge destructive cyclonic storm originating in tropical waters. Often
100 miles across.
Tornado:
Rotating funnel shaped clouds linking the ground to a large thunderstorm. The funnel cloud does not become a tornado
until it touches down. Diameter is often only around thirty feet, but can be up to half a mile. Usually happens in
spring/summer. Average forward speed is 50 km/hr. wind speeds within the tornado can range from 65 km/hr to 450
km/hr. The path of destruction is usually three to four kilometers long.
Waterspouts – Funnel clouds that touch water, usually slightly less powerful than tornadoes. Put your airplane into a
hanger before a storm, if you have one!
Fog is not associated with convection.
Dashed brown line on the weather chart is usually fog.
Fog formation requirements:
1. High humidity.
2. Condensation nuclei.
3. Very light surface winds.
4. A process to either cool or to add moisture, to get the condensation going.
A temperature to dew point spread of 3oC or less and dropping will probably lead to fog. Six fog types include radiation,
advection, upslope, frontal, steam, and ice.
Radiation fog:
Formed by radiation cooling on clear nights where relative humidity is high and light winds are present. Most
likely to be present shortly after sunrise.
Advection fog:
Formed by the horizontal movement of warm moist air over a cool surface. The thickest advection fog will usually form
at night with low winds. Common during winter warm-ups and early spring thaws. Typically dense and can last for
several days.
Upslope fog:
Moist air moves up rising terrain. Easterly wind blowing across the plains can cause upslope fog.
Frontal fog:
Precipitation from a warm front or cold front falls into colder air below it and ends up saturating it. More typical
with a warm front. Also known as precipitation fog.
Steam fog:
 Also known as arctic sea smoke. Typical over a lake/river/pond at sunset or sunrise. The process begins when cold dry
air blows over warm water. Water evaporates into the lower layers of the air, saturating it. As the excess water vapor
condenses, fog/mist forms.
Ice fog:
- Sometimes it forms when temperatures are significantly below zero.
- Often created by exhaust from engines or factories on cold winter days.
Naming conventions: Called Mist (BR) if visibility meets or exceeds 5/8ths mile. Called Fog (FG) if visibility is less than
5/8ths of a mile.
Haze - Forms on days with high temperatures and high humidity.
Each region in Canada has a FIC, eight in total: Whitehorse, Kamloops, Edmonton, Winnipeg, North Bay, London,
Quebec City, and Halifax. You usually contact a FIC by calling 1-866-WXBRIEF.
FSS’s are sub-locations that coordinate with the FIC. We normally contact them by radio while en route. They are
referred to as “Radio” and their service is Flight Information Services Enroute (FISE).
Sometimes, a FSS will be responsible for overseeing the control of a Class E control zone, and FISE will be done
by the nearest FIC via VHF repeater. Usually 122.5 or 123.XXX MHz.
Direct User Access Terminal (DUAT) – Can legally be used as the sole source of pre-flight planning info.
Automatic Terminal Information Service (ATIS) – A short, pre-recorded audio summary of the current weather at
an airport, which plays on constant repeat. Reduces radio congestion.
VOMET:
- Weather info via high frequency (shortwave).
- Used for North Atlantic crossings.
- Frequencies are found in the CFS.
PBS – Pilot Briefing Service
TWB – Transcribed Weather Broadcasts
CAVOK – Stands for Ceiling & Visibility OK. This means visibility is greater than or equal to 6 SM, ceiling is greater
than or equal to 5000’, and no cumulonimbus, precipitation, thunderstorms, fog, or drifting snow are present.
Understand the difference between current reports (METARs, AWOS, PIREPs) and forecasts (TAF’s and GFA’s).
Current reports are measurements, and forecasts are estimates.
METAR:
- Winds are knots true.
- Cloud heights are AGL.
- Visibility is in SM.
- Times are in UTC/Zulu.
You must know how to decode a METAR, and know all of the abbreviations. Memorize them. METAR includes: The type
of report, airport identifier, date/time, wind direction and velocity, visibility, runway visual range, weather phenomena,
sky coverage, temperature/dew point, altimeter setting, remarks.
SPECI – Special METAR report
RVR – Runway Visual Range
The RVR is always followed with either /D or /U or /N to represent downward, upward, or no change.
An Automated Weather Observation Station (AWOS) is noted by AUTO in the METAR. Use these observations with
caution! Heavy rain or blowing snow can cause incorrect readings.
If filing a PIREP, go through these nine items in order:
1.Location and time. 6. Wind direction and speed.
2. Altitude. 7. Turbulence.
3. Aircraft type. 8. Icing.
4. Cloud (base, amount, top). 9. Remarks.
5. Temperature.
Mandatory PIREP codes:
UA: Normal PIREP.
UUA: Urgent PIREP.
/OV: Location of the PIREP, in relation to a NAVAID, an aerodrome, or geographical coordinates. /TM:
Time the PIREP was received from the pilot, in UTC.
/FL: Flight level, essential for turbulence and icing reports.
/TP: Aircraft type, essential for turbulence and icing reports.
Optional PIREP codes: (at least one is required)
 /SK: Sky cover. Used to report the cloud layer amounts and the height of the cloud base. /TA:
Ambient temperature, important for icing reports.
/WV: Wind velocity referenced in terms of True north (magnetic north in US).
/TB: Turbulence intensity, whether it occurred in or near clouds, and duration.
/IC: Icing, reported by type and intensity or rate of accretion.
/RM: Remarks, any other weather conditions that are not covered already.
/WX: Flight visibility and weather.
Identifiers:
- 2 letters are NDB’s.
- 3 letters are VOR’s.
- 4 letters are airports.
- 5 letters are intersections.
You need to be able to completely decode all weather products for your written exam and flight test.
Notice To Airmen (NOTAM) – Contains info concerning “stuff that’s happening” which might affect pilots or normal
flight operations. Usually distributed at least five but no more than 48 hours in advance.
NOTAM’s are tailored by locations and by who is affected. There are about 210 files (location indicators) for Canada.
NOTAM Categories:
- Aerodrome: Anything within 25 NM of an aerodrome.
- Flight Info Region: Of general interest throughout the FIR.
- National (CYHQ): Affects the entire country.
Types of NOTAMS:
N – New.
C – Canceling.
R – Replacing.
J – Runway Surface Condition Report.
Q – Query or Response NOTAM.
The reason why the RSC report is identified by a J is because it stands for the James Brake Index. Always check the
NOTAMS!
Graphical Area Forecast (GFA):
Clouds and weather. Icing, freezing, and turbulence levels. Two sets of maps. Depicts the most probable meteorological
conditions expected to occur below the 400 Mb or 24,000’ level. Designed to meet en route weather forecasting and
pre-flight planning requirements of general aviation and regional air carriers. Issued four times daily, about half an hour
before the beginning of the forecast period. Valid for six hour periods starting 0000, 0600, 1200, and 1800 UTC. Seven
different coverage regions.
What is included in the GFA:
Six charts total for each six hour issue. Three for clouds and weather (CLDS/WX). Three for turbulence and freezing
level conditions (ICG/TURBO/FRIV). For each of these sets of three, a near term forecast, a 6hr forecast, and a 12hr
forecast are depicted individually. Note that the 12hr CLDS/WX chart also includes an IFR outlook for an additional
12-hour period, so it’s good for 24 hours. Speeds are in knots, and heights are ASL. Horizontal visibility is in SM.
Times are UTC/Zulu. You will be asked to interpret a GFA on your exam. The scale on the map is in NM. Memorize all
of the standard abbreviations that are found in the AIM meteorology section.
Category Ceiling Visibility:
- IFR: Less than 1000’ AGL, and less than 3 SM visibility.
- MVFR: 1000’ to 3000’ AGL, and 3 to 5 SM visibility.
- VFR: Greater than 3000’ AGL, and greater than 5 SM visibility.
Synoptic Features – Weather features that are generally at least a thousand kilometers across, ie. very large. Planetary
features are larger, and mesoscale features are smaller.
Mesoscale Levels:
1. Mesoscale Alpha: From 1000km across down to 200km.
2. Mesoscale Beta: From 200km across down to 20km.
3. Mesoscale Gamma: From 20km across down to 2km.
If a synoptic feature is forecast to be moving at five knots or faster, there will be an arrow and a speed value. For speeds
of less than 5 KTS, use the letters QS for quasi-stationary.
Clouds on GFA:
Bases and tops between the surface and 24,000’ are indicated. The tops of convective clouds (TCU, ACC, CB) are
indicated even if they extend above 24,000’ ASL.Cirrus clouds are not depicted. Cloud types will be indicated if
considered significant. A scalloped border indicates a ceiling where the sky is BKN or OVC. If the visibility is greater
than 6 SM, and the sky is SKC/FEW/SCT, then a scalloped border is not used. - When multiple layers are forecast, the
amount of cloud at each layer is based on the amount at that level, not overall. Bases and tops of each layer are indicated.
CIG stands for Ceiling, and implies AGL. Visibility of greater than 6 SM is listed as P6SM. A dashed green boundary
with an interior of solid slanted bars is used to enclose areas of intermittent or showery precipitation. A solid green line
with a dotted interior is used to enclose areas of continuous precipitation.
Convective storm clouds:
ISOLD – Isolated – less than 25%.
SCT – Scattered – 25% to 50%.
NMRS – Numerous – Greater than 50%.
Surface Based Layer:
- Referred to as OBSCD.
- Fog or Mist.
- VV into surface based layers is AGL.
Obstructions to Vision (enclosed within a dashed orange line):
LCL – Local – Less than 25%.
PTCHY – Patchy – 25% to 50%.
XTNSV – Extensive – Greater than 50%.
Wind barbs:
Used if the sustained speed is 20 KTS or more. Show speed and direction. The “feathers” on the barb correlate to the
numerical wind speed. G stands for gusting. Uses true wind direction.
Icing on Charts:
Icing is depicted in blue whenever moderate or severe icing is forecast. Areas of light icing are described in the
comments box.
Turbulence on Charts:
Depicted in red. Depicted whenever moderate or severe turbulence is forecast. The base and top of each layer are shown.
If turbulence is due to any of the following five conditions, the cause will be identified with the appropriate abbreviation:
MECH (mechanical), LLWS (low level wind shear), LEE WV (mountain wave), LLJ (low level jet), and CAT (clear air
turbulence).
Freezing level:
Contours are abbreviated by dashed lines. Height is measured ASL. Contour lines are at 2500’ ASL levels, starting at the
surface.
GFA Amendments:
Automatically amended by AIRMET’s. Happens if there are significant deviations from the forecast. The GFA is
automatically amended by SIGMET bulletins, even though that is not explicitly stated in the SIGMET itself. A chart will
be reissued with comments if necessary.
AIRMET – Airman’s Meteorological Event.
SIGMET – Significant Meteorological Event.

Look at the GFA first, then the TAF, then the METAR. This lets you look at the big picture first, then a five mile region,
then a point analysis.
Terminal Area Forecast (TAF):
Weather expected within 5 NM of the airport. Cloud heights are AGL. Wind degrees are true. Typically issued 4 times
daily, for either 12, 24, or 30 hour periods. To add a forecast for low-level non-convective wind shear, an example is:
WS018/34045KT, which means that the surface to 1800’ AGL has shear, and at 1800’ the wind is 340 o True at 45 knots.
- Wind shear below 1500’ AGL, if expected to be significant, is always included in the TAF.
Sky Cover in a TAF:
- Cloud layers forecast as per METAR.
- Only CB will be specifically identified in the forecast.
For a TEMPO notation, in order to be legal, the forecast “temporary” conditions cannot be expected to last more than
50% of the total duration of the TEMPO, and none of the intermittent occurrences can last for more than one hour.
FM – From, permanent change.
BECM – Becoming, permanent but gradual change.
PROB XX – Probability of XX%. Must be less than 50%.
 Remarks on TAF:
- RMK then details.
- Unique to Canadian TAF’s.
Upper Winds and Temperatures:
Referred to as the FD charts. Forecasts of wind direction and velocity, as well as expected air temperatures at specific
heights. - Forecasts are prepared every twelve hours. It is rare that these forecasts are completely accurate. In flight, be
prepared to use your ten degree drift lines. Wind direction is True, the speeds are in KTS. Code of 9900 stands for light
and variable winds, no wind corrections are required for the Nav Log. - Unlike many other areas, a code of a minus sign
does mean below zero degrees. If all temps are below 0o at higher levels, then the minus sign will be omitted, so you have
to look at other parts of the chart to verify. Field elevations above 1500’ will not report a 3000’ FD. Temps are not
reported on a 3000’ FD. Different format: ie. 1921+14 means wind direction 190 o, speed 21 knots, temperature +14oC. -
If the wind direction is between 51 and 86, subtract 50 to get the wind track, and also add 100 knots to the wind speed.
For example, 731960 means 230oT because (73-50)=23, x10=230, and wind speed is 119 knots, and the temperature is
minus sixty.
Airman’s Meteorological Advisory (AIRMET) - Short term weather advisory, designed to highlight weather that is
not described in the current GFA. Can be issued for:
-Instrument Meteorological Conditions (IMC). - Isolated thunderstorms.
- Freezing precipitation (unless it is in a SIGMET). - Wind varies by greater than 60 o direction from
- Moderate icing. forecast.
- Moderate turbulence.
SIGMETS are more severe, and might be issued for severe thunderstorms, squall line, hail, volcanic ash, hurricanes,
tornadoes, severe icing, marked mountain waves, widespread sand or dust storms, and low level wind shear.
In-flight SIGMETS will be broadcast on 126.7 MHz, and you can get more info on the FISE frequency. Weather Charts:
Surface charts and upper level charts (constant pressure charts). Most charts have pressures reduced to sea level. The
upper level charts do not. They are very different!
Surface Analysis Charts: Actual observed information.
Surface Prognostic Charts: Forecast info.
Surface Analysis Charts:
Actual weather as observed from the surface to 3000’ AGL. Information can be a few hours old since it can take up to
three hours to create a map. - Info is based on observations taken at 00Z, 06Z, 12Z, and 18Z. Allows you to see how the
weather has been developing over time. Most symbols are the same as the ones used in the GFA. Black location dot is
overcast. Barbs on a wind flag are 10 knots for each long barb, and less for shorter barbs. Wind always veers at the front.
Surface Prognostic Chart:
- Looks similar to the SAC. Don’t confuse them! Check the title.
- Issued 48 and 36 hours before the standard validity times of 00Z and 12Z.
Upper Level Charts:
Issued by the weather office at 00Z and 12Z. Can give us a 3D view of the weather. Analysis, not prognostic! Levels used
(standard) are 850 mB, 700 mB, 500 mB, and 250 mB. If you’re doing commercial or ATPL, you might use a fifth chart,
the 400 mB. There are also two prognostic charts: the Significant Weather Prognostic chart and the Significant Weather
Prognostic High Level chart (there are actually more, but these are the two commonly used in Canada).
When we are looking at a constant pressure chart, we are actually looking at the height of the air for a given pressure at
a given location.
Average altitudes for these pressure levels:
850 mB – 5,000’ ASL – 150 dM (decameters)
700 mB – 10,000’ ASL – 300 dM
500 mB – 18,000’ ASL – 570 dM
250 mB – 34,000’ ASL – 1050 dM
An airplane that is flying through different temperature columns of air up in the Flight Levels will have its True altitude
constantly changing. This does not matter! All the other airplanes will have their altimeters set to 29.92, and they will
also rise and fall with the changes.
Contour Lines – Lines connecting similar heights (of air pressure levels). Therefore, lines on a CPC are not isobars!
The whole horizontal plane of the map is an isobar, except in two dimensions as a layer, not as a single line. It is still
important to note that tightly packed contour lines are still indicators of high wind speeds.
Satellite imagery is a good complement to (not a replacement for) other information.
Geostationary Satellites:
 - Placed in orbit above the equator at an altitude of about 36,000 kms.
- The satellite’s motion through space matches the pace of the earth’s rotation.
- An observer on the ground sees the satellite as motionless in relation to the stars and earth behind. - The satellite
still completes one rotation of the earth per day.
The National Oceanic & Atmospheric Administration (NOAA) uses three geostationary satellites for imagery: GOES
West, East, and South. These normally each see one half of the earth, a disc which depends on their orbital parking
spot. They produce a full image every thirty minutes, although they can be tasked to “rapidly scan” smaller areas
more quickly. However, because they are in orbit over the equator, they don’t provide accurate information at latitudes
over 60oN.
Polar Orbiting Satellites:
Orbit at an altitude of about 850km. They complete an orbit every 105 minutes, or 14 times/day. Because the earth
rotates beneath them, they “appear” to move west by about two time zones per orbit. Over any given time zone, there are
about two passes per day, which averages to about one pass per day during visual daylight hours. Currently, there are two
NOAA satellites working, one on each side of the planet. Together, they provide images once every six hours.
They can provide images at very high resolution since they’re so low.
Image types can be visible or IR. Depending on the wavelengths used, IR can tell us surface temps, cloud top temps, or
moisture content of the atmosphere. For white temperature labels, the coldest temperatures are bright whites. On color
temperature labels, green/purple are warm and down to orange/yellow/red are very cold. These are the Environment
Canada standard colors.
For visible satellite images, they use a white albedo style. IR images use a temperature scale.
Infrared Images:
Fog, which can be quite shallow, can be hard to pick out if it is the same temperature as the ground below it. In an
inversion, where temperatures aloft can be even higher than the ground, clouds can even appear as dark objects. The
typical resolution on IR images is about 4km at the equator and deteriorates further north, especially past 60o latitude.
Visible Images:
Need to be taken during daylight hours. Appearance changes throughout the day as the angle of incident light changes. -
Clouds are generally defined better than on IR. Banks of fog and large cumuliform clouds are easy to see. Resolutions are
around 2km at the equator and deteriorate further north, especially past 60o latitude.
Water Vapor Imagery:
Starting to become more common. Does not tell us where clouds are, but does tell us where there is a lot of moisture in
the air. - Areas of high moisture content will be bright white, while areas that are relatively dry will be a dark shade, or
black.