The Mysterious
Dumbfounding Data or Dangerous Disregard?
by Matt McDaniel
D:
E
arly this year I was reviewing and preparing material for my series of WAAS/ block (Figure 1). At first I thought
Advanced IFR refresher seminars, and while doing so I noticed a symbol on an it might be indicating that the
approach plate that I had never seen before. It was the letter “D” placed on airport was within Class D air-
a black square background. The symbol appeared on the airport diagram portion space, but in fact, the airport
of a NACO Terminal Procedure Chart (Approach Plate), near the field elevation in question was uncontrolled. I
went to the legend at the front
of the Terminal Procedures
booklet – no luck, the symbol
was simply not there. To add
more confusion, the symbol
was appearing inconsistently.
At some airports it was on each
approach plate’s airport dia-
gram, but not the full-page
airport diagram. At other air-
ports it was on the full-page
airport diagram, but not the
individual approach plates.
And at other airports, it was
either on both or nowhere to
be found at all. Confused yet?
I certainly was.
I placed a few calls to my lo-
cal FSDO, where I personally
know several FAA inspectors. I
asked about this mysterious D
symbol, but no one could answer
definitively. I made a mental note
to keep searching and returned
to work on my seminar presen-
tation. You can probably guess
what happened next. The first
time an approach plate with
this new symbol appeared in
front of a room full of pilots at
the seminar, one of them asked,
“What’s that D on the airport
diagram?” I admitted my search
for its meaning, so far, had been
frustrating. I promised to get the
answer for everyone as soon as
possible. Within two days, one
of the seminar attendees was
hot on the trail of the mysteri-
ous D, gathering enough infor-
mation from his local FSDO
(different than mine) to get us
FIGURE 1: A St. George, Utah approach plate both digging in the right places
with the D symbol in the airport diagram section (lower right). for the answers.
Volume 4, Number 3 CIRRUS PILOT • 15
Enough with the suspense; the
D symbol indicates that there is
Declared Distance Information
(DDI) available for that airport
and that this DDI is not on the
airport diagram. But, that is only
the beginning of the answer. The
complete answer is like the body
of an octopus with numerous
tentacles of related information
attached to it. Let’s proceed to
dissect this octopus, one piece at
a time.
When, Where & Why?
When: The D symbol is brand
new and is being implemented
by the FAA and the National
Aeronautical Charting Office
(NACO), but it will take time
to get it into the system consis
tently. As of this writing, it is
so new that the symbol doesn’t
even appear in the Terminal
Procedures Legend sections, al-
though it will eventually.
Where: At airports where the
D symbol is appropriate, it will
appear on the full-page airport
diagrams within the Terminal
Procedures booklets and the
Airport/Facility Directory (A/FD)
(Figures 1 & 2). At airports large
enough to merit a full-page dia-
gram, the D-symbol could be
eliminated from the small airport
diagram appearing on each indi-
vidual approach plate. If said
airport does not have a full-page
airport diagram, the D symbol
will appear on each approach
plate’s airport diagram.
Why: The new D symbol serves FIGURE 2: The full-page airport diagram for Springfield, Ill.
two purposes: First, it allows a Note the D symbol in the upper-left corner.
great deal of information to be
excluded from the airport diagram. This can greatly de- Declared Distance Information (DDI)
clutter the diagram, making the remaining information DDI is runway length information that is different than
more readable. Second, it tells the pilot that the DDI the simple total runway length that is shown on the airport
can be found in the A/FD. This encourages pilots to refer- diagram. DDI includes a variety of lengths for a given
ence the directory in their flight planning. It contains a runway that break down its total length into distances
wealth of information, which is all-too-often overlooked which should be considered for normal, abnormal, and
by pilots. Use of the A/FD has been declining for years, emergency operations (Figure 3).
yet even the advanced GPS databases we’ve all grown
used to in recent years don’t include much of the infor-
RUNWAY DECLARED DISTANCE INFORMATION
mation found within its pages. The D symbol is another
way the FAA can encourage pilots to reference the A/FD, RWY 13: TORA-7400 TODA-7400 ASDA-7217 LDA-7217
where they can find not only the DDI, but all the other RWY 31: TORA-7400 TODA-7400 ASDA-7000 LDA-7000
available safety data. Note: Digital A/FDs are now available
free at www.faa.gov. FIGURE 3: Coded Runway Declared Distance Information (DDI)
from the Airport/Facility Directory, for Springfield, Ill. (KSPI).
16 • CIRRUS PILOT
First, I’ll define the terms and discuss a clearway is a safety enhancement
the lengths associated with the DDI in- to all aircraft utilizing that runway. A
formation. DDI includes: clearway is an area beyond the runway,
TORA – Takeoff Run Available: The at least 500 feet wide, centered on the
length of runway available and suit- extended runway centerline, and under
able for the takeoff ground run. the control of the airport authority. It can
be thought of as an imaginary surface
TODA – Takeoff Distance Available: sloping upward from the departure end
The length of the takeoff run available of the runway (at no steeper than a
(TORA), plus the length of the clear- 1.25% slope) above which no object
way, if provided. or terrain may protrude. An exception
ASDA – Accelerate-Stop Distance Avail is that threshold lights may protrude
able: The length of the takeoff run into the clearway if their height at the
available, plus the length of the stop- threshold is 26 inches or less, and they
way, if provided. are located on each side of the runway.
Certain turbine airplanes certified prior
LDA – Landing Distance Available:
to August 1959 may include clearways
The length of the runway that is avail- FIGURE 4: A stopway/blastpad. The as little as 300-feet wide in their perfor-
able and suitable for the landing yellow chevron markings indicate it mance calculations.
ground run. This would exclude any is not to be used for any normal
runway prior to a displaced threshold aircraft ground operations. Stopway: An area beyond the run-
or otherwise unusable pavement due way, centered upon the extended run-
to glidepath angle, obstructions and/or other landing way centerline and no less than the runway width, able
safety factors. to support an airplane during an aborted takeoff without
causing structural damage to the airplane. This area must
As you can see, the basic length of a runway simply be designated by the airport authority for use in deceler-
does not tell the whole story of that runway’s usability. To ating an airplane during an aborted takeoff. Stopways
further clarify the above, let’s define some of those terms: often double as blastpads, or areas free of items that
Clearway: In a certification sense, this term applies could be damaged by a departing aircraft’s jet or prop
only to turbine-powered airplanes. Yet, the existence of blast (Figure 4).
Volume 4, Number 3 CIRRUS PILOT • 17
Accelerate-Stop Distance: While this term generally applies to multi-engine air-
craft, it can certainly be related to single-engine aircraft for the purpose of prudent
Piper. Step In. preflight planning of the runway distance required under a worst-case scenario.
Step Up.
Officially, it’s the distance required for a twin-engine airplane to accelerate to a
specified speed (generally a takeoff decision speed or V1) and, assuming failure of
an engine at the instant that speed is attained, to bring the airplane to a stop. For
single-engine aircraft, this distance can be estimated by adding the computed takeoff
ground roll to the calculated landing ground roll.
Runway Safety Area (RSA): The surface surrounding a runway, suitable for reduc-
ing the risk of aircraft damage during an undershoot, overshoot, or runway excursion.
The RSA dimensions vary, but all RSAs shall be:
a. Cleared, graded and free of potentially hazardous surface variations;
PIPERJET: b. Drained to prevent water accumulation;
360 ktas l 35,000 ft l 1,300 nm c. Capable of supporting snow removal and fire/rescue equipment and occasional
It Machs! aircraft passage without causing structural damage to the aircraft;
d. Free of all objects except those necessary to be placed in the RSA due to their
function. Those objects must be on low-impact-resistant supports no higher than
three inches above grade.
Displaced Thresholds
Most likely, these terms are not new to
MERIDIAN G1000: you. It is worth pointing out that a displaced
260 ktas l 30,000 ft l 1,000 nm
threshold will shorten a runway’s usable land-
Turboprop l Pressurized l Garmin Avionics
ing distance, but not affect its usable takeoff
distance.
Threshold: The beginning of that portion of
the runway suitable for landing.
Displaced Threshold: A threshold that is
located at a point on a runway, other than the
MERIDIAN: designated beginning of the runway.
260 ktas l 30,000 ft l 1,000 nm
Turboprop l Pressurized l Avidyne Avionics A threshold is generally displaced to allow
the glidepath to the touchdown zone to clear
obstructions and/or to comply with noise re-
strictions. Typically, the pavement prior to the
displaced threshold is still perfectly suitable
for the takeoff roll or the landing rollout from
the opposite direction (Figure 5). Therefore, FIGURE 5: A displaced threshold.
it is included in basic runway length. So, how The white arrows point the pilot to
MIRAGE: the landing threshold of the runway,
are you considering it when calculating your
213 ktas l 25,000 ft indicated by the white band across
Landing Distance Required (LDR)? Specifi-
1,343 nm l Turbocharged l Pressurized the runway end. The area prior to the
cally, you should be excluding it and consid-
displaced threshold may be used for
ering it unusable when it’s at the approach taxi, takeoff and landing rollout from
end of your landing runway. the opposite direction.
Distance Beyond Glideslope
When conducting precision instrument approaches, always consider that any
MATRIX: amount of runway under the glideslope will be mostly unusable. Distance Beyond
213 ktas l 25,000 ft Glideslope is the effective runway length for landing and is published by Jeppesen on
1,343 nm l Cabin-class l Six seats the back of their Airport Diagrams. Typically a precision glideslope is designed to
intersect the runway 1,000 feet from the threshold (denoted by the 1,000-foot fixed
distance markers on instrument runways).
Climbing Through
The Flight Levels Engineered Materials Arresting System (EMAS)
Has Never Been Easier. EMAS is a runway safety device that has gained wide acceptance in recent
years and is being installed mainly at runways with limited or no stopways and /
PiPer.com 866.FLY.PiPer or where dangerous terrain or obstructions exist beyond the stopway /EMAS area.
Not pictured – Seneca V, Seminole, Warrior III
It consists of high - energy - absorbing materials installed in the RSA (Figure 6).
May/June 2009
The material is designed to unforgiving surfaces. EMAS may be located as close at
crush under the weight of 35 feet from a runway end and should never be taxied or
a commercial aircraft and driven on.
exert decelerating forces on
the landing gear. EMAS is a Usable Runway
fabulous idea and at many Hopefully, this information has made it obvious that
airports it cannot be installed the length of a usable runway can vary wildly from its
quickly enough. For instance, basic, published length. This is true for normal, abnormal
FIGURE 6: A stopway/blastpad with
when a 737 overran its run- and emergency situations. In comparison to basic runway
EMAS installed. The EMAS section
is grey and slightly raised above the way at Chicago -Midway on length, usable length can be shorter in the case of dis-
rest of the stopway. This example December 8, 2005, it ca- placed thresholds, missing or non-conforming clearways,
is installed on Runway 12R at reened through the approach obstructions, glidepath variations, etc. It can be longer
Minneapolis/St. Paul International lights, blast fence, and air- than the basic length in the case of suitable clearways,
Airport, due to a deep and abrupt port perimeter wall, crushing stopways, RSAs, etc. When your runway distance is per-
terrain dropoff into a river gorge formance critical, will you know the correct length to apply
a car outside the airport
just beyond the EMAS area.
property (killing a child in to your situation? The safety of you, your passengers and
the car). Had that runway had EMAS installed, there is a innocent bystanders may very well depend on it. COPA
high probability the 737 would have been decelerated
within the airport property, preventing a child’s death. About the Author: Matthew McDaniel is a Master & Gold Seal
Yet, as pilots of smaller aircraft, we must bear in mind CFII, ATP, MEI, AGI, IGI and CSIP. In 19 years of flying, he
that EMAS is designed for commercial aircraft. It may has logged over 10,000 hours total and over 4,000 hours of
instruction-given. As owner of Progressive Aviation Services, LLC
not crush under the weight of small GA aircraft, limiting
(www.progaviation.com), he has specialized in Cirrus instruction
its effectiveness on deceleration; or it may literally tear since 2001 and has held the CSIP credential since the first day it
the gear out from under a Cirrus-sized aircraft, causing was available in late 2003. Currently, he’s teaching Cirrus clients
significant aircraft damage and possible injury to persons nationwide via personal flight training and seminars. He’s also an
onboard. Yet, even those options seem better than the airline and corporate pilot, having flown a wide variety of airliners
alternatives at airports where significant overruns can & corporate jets, holding five turbine aircraft type-ratings. Matt
mean a collision with buildings, bodies of water or other can be reached at: matt@progaviation.com or 414-339-4990.
20 • CIRRUS PILOT May/June 2009
