PERFORMANCE

Runway
TORA (Take off Run available): It is the length of the runway suitable for normal operations.
Stop-way: The area at the end of the Take-Off run of the same width as the runway, extended above
the centre line which is able to support the Aircraft during aborted Take-Off operation without
causing any structural damage to the aircraft.
Clearway: It is the area beyond the runway not less than 152m wide located above the extended
centre line in which no obstacle must exist except runway threshold lights and it gives a slope of
1.25%. This can be on the water or on the land as well.
Displaced Threshold: An area at the starting of the runway in which take off is possible but not the
landing.
ASDA (Accelerated Stop Distance Available):
TODA (TAKE OFF DISTANCE AVAILABLE): TORA + CLEARWAY
Balanced Field: When TODA = ASDA. It gives highest possible take off weight in the given condition
and given runway.
 Speeds
Vmcg:
Min speed at which if one engine becomes inoperative AC can still be directionally controlled
with the primary controls only. Assuming:
Max rudder force of 150LBs,
Engine failed is critical engine,
cross-wind is coming from the dead engine: 7kts.
Without using thrust on the live engine
Landing gear extended
Vmca: Minimum controllable speed in air.
Minimum spreed at which if one engine becomes inoperative then AC can be directionally
controlled. Assuming:
Engine failed is the critical engine.
Max rudder force of 150lbs.
Bank angle not exceeding 5º.
Directional change not exceeding 20º.
Without reducing thrust on the live engine.
Aircraft out of ground effect.
Under-carriage retracted.
V1: Action initiation/Decision speed
It is the speed at which the action to continue take-off or abort take-off can be taken. If engine
failure happens before V1, it is mandatory to abort. Engine failure happens after V1, it is
mandatory to Take-off. However, the action to abort the take-off can be taken if there is a reason
to believe that aircraft is unable or unsafe to fly. Conditions:
V1 ≥ Vmcg
V1≤ Vr
V1 ≤ Vmbe
V1 < V2
Vmbe: Max break energy speed
Speed after which if the brakes are applied then due to the extreme heat, tyre fuse plugs may
melt and loss of braking may happen.
Vr: Max Rotation speed
Speed a which the action to rotate the AC will be taken. Limits:
Vr ≥ V1
Vr > 1.05% Vmca
Vr > 1.10 Vs
Vmu: Min unstick speed
Speed at which main landing gears will become airborne.
Vlof: min lift-off speed
Speed at which main landing gears will become airborne and it is usually 5% higher than Vmu.
V2: take-off safety speed
 It is the speed that has to be achieved till screen height and it gives 20% stall margin and 15º
manoeuvre capability.
V2 ≥ 1.2 Vs
Aircraft weight↑= V2 ↑
Higher the flaps,↓ the V2.
Forward CG = More V2

Segments of Flight

First segment:

Action is to retract landing gear

Climb gradient positive,
Speed V2
Flaps/Power: Take- Off setting

Second Segment

It will start from landing gear retracted to 400ft

Action is to clear obstacles
Climb gradient 2.4%
Speed V2
Flaps/Power= Take-off setting
Landing Gear retracted

Third Segment

Acceleration segment
Starts from 400ft till flaps retracted.
Climb gradient: 0-1.2%
 Flap retraction speed (clean configuration speed)
Max continuous thrust

Fourth Segment

Starts from flap retraction to 1500ft.

Climb gradient 1.2%
Climb speed
Maximum continuous thrust
Flaps and landing gear retracted.

What is Gradient?
Gradient: it is the ration of height divided by horizontal distance.
Gross gradient: It is the performance of the AC in actual conditions.
Net Gradient: It is the gross gradient reduced as per regulations.

Cost index: It is the ration of variable cost to the fuel cost. Less Cost index means AC is consuming
less fuel in more time.
Optimum altitude: Altitude at which best fuel mileage is achieved. It depends on the overall weight
of the aircraft, hence when the AC flies, it burns fuel and optimum altitude increases.
Max Range cruise: A technique which gives best fuel mileage for a given altitude and weight which
means when the AC maintains a constant altitude then the thrust will be reduced with the reduction
in the weight.
Long Range cruise: It is the speed above the max range cruise which results in 1% less fuel milage
but give 2-3% faster cruise speed.
 Density, temperature, weight and performance

When the overall weight of the aircraft increases, performance reduces.

1. V speeds increase (V1, V2, Vr)
2. Stopping, landing and take-off distance increase.
3. Climb Gradient, ROC and ceiling height will reduce.
4. ROD will increase
5. Min Stall speed will increase and Max stall speed decreases hence the safety margins will reduce.
6. Drag, fuel consumption increases. Range decreases.
7. Manoeuvre ability reduces and stress on the AC will increase.

Centre of Gravity (CG)

It is the point of balance. The point where all the three axis pass through.
It is the point where the total weight of AC will act through
Datum: It is the point on the longitudinal axis, from where all the CG will be measured.
Balance Arms: It is a distance from the datum to the current centre of gravity.
Ballast: It is the temporary or permanently installed weight in the AC which is used to bring current
CG within the limit. It can be fuel as well.
 Payload
Basic Empty Weight: Structure + Standard items

Standard Items: Emergency equipment, Unusable fuel and oil, supplementary items and
ballast.

Dry operating weight: (DOW) BEW+ Variable load

Variable Load: Crew and crew baggage, food and catering items, lavatory chemical and waters.

Passenger service equipments (blankets etc).

Max Zero Fuel Weight (MZOW)= DOW+ Traffic Load
It is the maximum permissible Take-off Weight of an aircraft without useable fuel.

Traffic Load: it is the total of passengers, cargo any revenue or non-revenue load.
Pay Load: It is that part of the traffic load from where revenue is generated.
Useful Load: Traffic load + Useable fuel.

Max Take-Off Weight MTOW: Max permissible Take-Off weight of an aircraft in ideal conditions. It
defines structural integrity of the AC
Performance limited Take Off Weight PTOW: Max permissible TO weight in actual conditions.
Regulated Take Off Weight RTOW: It is the minimum of MTOW or PTOW
Max Landing Weight MLW: Max permissible landing weight of aircraft in ideal conditions.
Performance-Limited landing weight PLW: Max permissible landing weight of an aircraft in
actual conditions.
Regulated landing weight RLW: Minimum of MLW and PLW
 Fuel
Trip Fuel: Used to complete take off climb, cruise, descent and landing.
Contingency Fuel: Fuel taken for unforeseen circumstances which is 5% of the trip.
Alternate fuel: fuel required for 1 missed approach at destination and transit to the alternate.
Reserve: Fuel that has to be in the fuel tanks at the time of landing which is 30mins for the Jet engine
and 45 mins for the piston engine.