Takeoff and Landing
Performance
A significant number of accidents and
incidents occur during takeoff and landing.
Ensuring that your takeoff and landing can be
conducted within the confines of the runway
will significantly contribute to the safety of
these critical phases of flight.
Every effort is made to ensure that the information in this booklet is accurate and up to date at the time
of publishing, but numerous changes can occur with time, especially in regard to airspace and legislation.
Readers are reminded to obtain appropriate up-to-date information.
Contents
PIC Responsibilities................5
How to Comply............................ 5
Performance Factors..............6
Weight......................................... 6
Air Density................................... 6
Wind.......................................... 10
Slope.......................................... 12
Surface...................................... 12
Obstacle Clearance.................... 14
Flap Setting................................ 14
Ground Effect............................ 15
Tyre Pressure............................. 16
Wing Surface............................. 16
Other Considerations...........17
Runway Distance....................... 17
Pilot Technique.......................... 17
Speed Control............................ 18
Decision Points.......................... 18
Contingencies............................ 19
Determining Performance....20
Group Rating System................ 20
P-Charts..................................... 22
Aircraft Flight Manual................ 30
Air Transport Operations............ 32
Know Your Aircraft..................... 33
Conclusion.............................34
Performance Questions............. 35
CAA Web Site
Every effort is made to ensure that the information in this booklet is accurate and up-to-date at the time
of
printing,
butweb
numerous
can occur
with
time, especially
in regard to legislation.
See
the CAA
site forchanges
Civil Aviation
Rules,
Advisory
Circulars,
Readers
are reminded
to obtain
appropriate
information.
Airworthiness
Directives,
forms,
and moreup-to-date
safety publications.
4
PIC Responsibilities
Civil Aviation Rules clearly indicate that it is the responsibility of the
pilot in command to ensure that they operate their aircraft in a safe
manner with respect to takeoff and landing performance. In particular,
rule 91.201(2) states that “A pilot-in-command of an aircraft must …
during the flight, ensure the safe operation of the aircraft and the
safety of its occupants…”.
How to Comply
If you are operating under Part 135, there
If you are operating under Part 91,
will be specific performance requirements
you will need to meet – these are briefly
Advisory Circular 91-3 Aeroplane
Performance Under Part 91 provides
discussed later in this booklet.
guidance on how best to comply with
Note that the group rating system,
rule 91.201(2). Essentially, AC91-3 says
for instance, is quite conservative and
that you can determine the takeoff and
sometimes shows that an aircraft will
landing performance of your aircraft by
not fit on to a particular runway when
one of the following three methods:
in fact P-chart calculations (which are
•
Group Rating system;
more precise) show otherwise. It is
•
P-charts; or
•
Approved Aircraft Flight Manual data.
quite acceptable to select the method
that shows that the operation can
be performed within the aircraft’s
AC 91-3 also provides performance
performance limits.
correction tables for surface type, slope,
All of these three methods are
and contaminated runway surfaces,
discussed, with worked examples,
since this information is often omitted
later in this booklet.
from many light aircraft Flight Manuals.
5
Performance Factors
Many different factors affect aircraft performance.
Weight
Effect of Pressure on Density
The gross weight of the aircraft directly
Atmospheric pressure decreases with
affects stall speed, a 10 percent increase
altitude, because the air near the earth’s
in weight increasing the stall speed by
surface is compressed by the air above it.
5 percent.
As altitude increases, air is free to expand
and therefore becomes less dense.
Takeoff
Liftoff speed is generally about 15 percent
Effect of Temperature on Density
above the stalling speed, so an increase in
Temperature generally also decreases with
weight will mean a higher liftoff speed.
altitude. This causes the air to contract
In addition to the higher speed required,
and become denser. However, the drop
acceleration of the heavier aeroplane is
in pressure as altitude is increased has
slower. Hence, a longer takeoff distance
the dominating effect on density when
will be required. As a general rule of thumb,
compared with the effect of temperature.
a 10 percent increase in takeoff weight has
Effect of Humidity on Density
the effect of increasing the takeoff run by
Water vapour is lighter than air; consequently
about 20 percent.
moist air is lighter than dry air. It is lightest
Landing
(or least dense) when, in a given set of
Heavier landing weights require higher
conditions, it contains the maximum amount
approach speeds, which means the aircraft
of water vapour.
will have greater momentum and require
International Standard Atmosphere
more runway in which to land and stop.
A standard atmosphere has been
A 10 percent increase in landing weight has
established to enable comparison of aircraft
the effect of increasing the landing distance
performances, calibration of altimeters and
by about 10 percent.
other practical uses.
Air Density
In the International Standard Atmosphere
As air density decreases, both engine and
a particular pressure and temperature
aerodynamic performance decrease.
distribution with height is assumed.
6
At sea level the pressure is taken to be
1013.2 hPa and the temperature 15˚C.
In this ‘average’ atmosphere, any pressure
Height above
Sea Level
(Thousands
of feet)
Temp
(˚C)
Press.
(hPa)
Relative
Density
40
-56
188
0.247
level has a standard corresponding altitude
Cirrus clouds
called the pressure altitude (based on a
lapse rate of approximately one hPa per
35
-54
239
0.311
30
-44
301
0.375
30 feet at lower levels) and a corresponding
temperature called the ISA temperature.
Pressure altitude is the height that will
register on a sensitive altimeter whenever
Mt Everest
its sub-scale is set to 1013.2 hPa.
In the standard atmosphere, temperature
25
-34
377
0.449
20
-25
466
0.533
falls off with height at a rate of 1.98˚C per
1000 feet up to 36,090 feet, above which it
is assumed to be constant (see Figure 1).
Warm air is less dense than cold air.
High Cumulus clouds
Thus, when the temperature at any
15
altitude in the atmosphere is higher than
-15
572
the temperature would be in the standard
0.629
Mt Cook
atmosphere at the same altitude, then the
air at that altitude will be less dense than
10
-5
697
0.739
5
+5
843
0.862
in the standard atmosphere.
ISA also assumes dry air. In normal
conditions, the amount of water vapour
Stratus and Nimbus clouds
in the air does not make a significant
difference to its density. However, as warm
0
air can contain much more water vapour
than cold air, at high temperatures and
+15
1013
Sea level
1.000
high humidity, the reduction in density may
become significant and degrade aircraft
Figure 1
takeoff performance accordingly.
The International Standard Atmosphere
7
Density Altitude
Density altitude can be calculated by taking
Density altitude represents the combined
pressure altitude and adding (or subtracting)
effect of pressure altitude and temperature.
120 feet for each 1˚C above (or below) ISA.
It is defined as the height in the standard
When an aircraft is taking off at a density
atmosphere, which has a density corre-
altitude above ISA sea level, it will still get
sponding to the density at the particular
airborne at the same indicated airspeed
location (on the ground or in the air) at which
as at sea level, but because of the lower
the density altitude is being measured.
density the true airspeed (TAS) will be
Aircraft performance depends on air density,
greater. To achieve this higher speed with
the same engine power, a longer takeoff run
which directly affects lift and drag, engine
power, and propeller efficiency. As air
will be needed.
density decreases, aircraft performance
The effect of a high-density altitude on the
decreases. Density altitude, therefore,
power developed from the unsupercharged
provides a basis for relating air density to
engine is adverse, and less power will be
ISA, so that aircraft performance can be
available for takeoff. (When taking off from a
readily determined.
high-density altitude aerodrome, the engine
8
• The takeoff distance is increased by
will not even develop the power it is capable
one percent for every 1˚C above the
of unless the mixture is correctly leaned.)
standard temperature for the aerodrome
An increase in density altitude, therefore,
elevation.
has a two-fold effect on the takeoff:
• Rate-of-climb and angle-of-climb are
• An increased takeoff speed (TAS) is
noticeably reduced, as is obstacle
required.
clearance after takeoff.
• Engine power and propeller efficiency
High-density altitudes are found most
are reduced.
commonly at high-elevation aerodromes
• The approximate effect of these two
when the temperature is high.
components on takeoff and landing
Low atmospheric pressures will accentuate
performance are:
the effect. Taking off with a heavy aeroplane
• The takeoff distance is increased by one
in these conditions is fraught with danger.
percent for every 100 feet of aerodrome
Your takeoff performance sums have got to
pressure altitude above sea level, and
be right.
the landing distance by one percent for
every 400 feet.
9
Glentanner aerodrome has an
elevation of 1824 feet AMSL.
Wind
Landing distances are similarly increased.
Tailwind takeoffs and landings should be
Headwind
avoided unless it can be established with
Taking off into wind results in the shortest
absolute certainty that there is sufficient
takeoff run and the lowest groundspeed
distance available to do so.
on liftoff. If it becomes necessary to
abandon the takeoff, not only will the lower
Crosswind
groundspeed make it easier to stop, but also
A crosswind situation will affect takeoff
the shorter takeoff run means more runway
and landing performance, mainly because
available to do so. Climbing into wind
of the reduced headwind component.
gives a lower groundspeed and therefore a
If the wind is 30 degrees off the runway
steeper angle of climb after takeoff; this is
heading, the headwind is effectively
good for obstacle clearance.
reduced by 15 percent. If the wind is
Landing into wind results in a lower
45 degrees off, the headwind is reduced
groundspeed and shorter landing run.
by 30 percent.
Takeoff and landing distances are reduced
by about 1.50 percent for each knot of
Gusting Winds
headwind up to 20 knots.
A gusting wind situation will require that
you keep the aeroplane on the ground for
Tailwind
a slightly longer period of time to provide
Taking off downwind results in a much
a better margin above the stall, thereby
longer distance to get airborne and a
increasing your overall takeoff roll.
decreased angle of climb, which is bad for
Gusty conditions also necessitate a higher
obstacle clearance.
approach speed, which results in a longer
For a 5-knot tailwind component, the takeoff
landing roll.
distance should be multiplied by 1.25 and
for ten knots by 1.55.
10
Turbulence and Windshear
The possibility of turbulence and
windshear should be considered
when working out takeoff or landing
distances. Windshear is a change in
wind velocity (speed and/or direction)
over a very short distance.
The presence of windshear can cause
sudden fluctuations in airspeed after
takeoff or during an approach.
Hangars, buildings and areas of trees
all influence the flow of the wind near
them. The mechanical turbulence
resulting from this disturbed airflow
may become very marked in the lee
of the obstruction.
In winds below 15 knots, turbulence
occurs in the lee of the obstruction and
may extend vertically to about one third
higher again than the obstruction.
In winds above 20 knots, eddies can
occur on the leeward side to a distance
of about 10 to 15 times the obstruction
height and up to twice the obstruction
height above the ground.
11
Slope
15 metres (50 feet) height difference on a
750-metre strip gives an answer of 0.02,
An uphill slope increases the takeoff ground
or a 2 percent slope.
run, and a downhill slope increases the
landing ground run. For example, an upslope
Surface
of 2 percent increases takeoff distance by
about 15 percent and a 2 percent downslope
Takeoff
decreases it by about 10 percent.
Grass, soft ground or snow increase the
Slopes can be calculated from known or
rolling resistance and therefore the takeoff
estimated information. Divide the difference
ground run will be longer than on a sealed
in height between the two strip ends by
or paved runway.
the strip length (working in the same
Dry grass can increase takeoff distance
units of measurement). For example,
by up to 15 percent. Long wet grass can
12
further increase this distance depending
Landing
on the length and wetness of the grass and
On landing, grass or snow cause an
the weight and wheel size of the aircraft.
increased ground roll, despite increased
Aircraft type is a big factor here – attempting
rolling resistance, because the brakes are
to takeoff on such a surface in a Piper Cub is
less effective.
an entirely different proposition to a Cessna
Long wet grass can mean a very large
172 for example.
increase in the landing run due to this effect.
It is often inadvisable to takeoff in long wet
grass, and it can be impossible.
Puddles of water on the runway can also
significantly retard acceleration.
13
Obstacle Clearance
by the number of nautical miles covered
Plan to clear obstacles on the climbout path
per minute eg, 500 fpm/1.1 NM per min =
454 feet per NM of climb performance
by at least 50 feet.
(this assumes a groundspeed of 66 knots).
Consider what your aircraft’s climb gradient
is likely to be as part of your takeoff
This will then give you a good indication of
performance calculations – especially
whether you will be able to maintain safe
if terrain, wires, and the possibility of
terrain and obstacle clearance.
Photo courtesy of Kaye Nairn
downdraughts are factors in the climbout
path. Calculating the gain-of-height per
Flap Setting
mile is straightforward. Simply divide the
Flap reduces the stalling speed and enables
aircraft’s known rate-of-climb performance
you to lift off at a lower indicated airspeed.
14
wing out of ground effect. Thus the wing
This can mean a shorter ground run, but
is more efficient while in ground effect.
it may not give any reduction in takeoff
distance to 50 feet because flap usually
While this can be useful on occasions, it can
causes a reduction in the rate of climb.
also trap the unwary into expecting greater
climb performance than the aeroplane is
The recommended flap setting should
capable of sustaining.
always be used.
On landing, ground effect may produce
Ground Effect
‘floating’ and result in a go-around (or an
When flying close to the ground, the wing
overrun, if the danger signs are ignored)
generates less induced drag than around a
particularly at very fast approach speeds.
15
Low-wing aeroplanes are more sensitive
satisfactory obstacle clearance as result,
to ground effect than high-wing ones.
which is all the more reason for making
Ground effect makes it possible to lift off
sure that you get it right first time.
at too high a pitch angle, or too soon with
Tyre Pressure
a heavy load. Taking off too steeply (or too
Low tyre pressure (perhaps hidden by grass
soon) will cause the angle of attack to be
or spats) will increase the takeoff run.
at or near that of a stall, with drag and
thrust nearly equal, and thus no chance
This is something that should always be
of accelerating.
checked during the pre-flight walk around.
Don’t force your aircraft to become
Wing Surface
airborne too soon.
Deposits on the wing surface, such as
Let it lift off when it’s ready to fly. Utilise
raindrops or insects, can have a significant
ground effect by briefly holding the aircraft
effect on laminar flow aerofoils such
in ground effect to let it accelerate to best
as used on some self-launching motor
angle-of-climb speed before climbing out.
gliders and high performance home-built
This is especially important when departing
aeroplanes. Stall speeds are increased and
from a short soft field with obstacles.
greater distances are required.
If you inadvertently leave ground effect
The presence of surface frost, ice or snow
too soon, and the aeroplane is not able
affects any aerofoil, including the propeller.
to accelerate to its proper climb speed,
Minor hangar rash or dents on the lifting
the only way to retrieve the situation is
surfaces or propeller will also degrade
to lower the nose, allow the aircraft to
performance. Keep all lifting surfaces
accelerate, and then climb. The problem
damage-free and clean to ensure maximum
is, that you may not be able to achieve
performance.
16
Other Considerations
It is good airmanship to think about what technique, speed,
and decision point, you will use for every takeoff and landing.
Runway Distance
Pilot Technique
Information on available runway distances is
Ensure that recommended short-field
published in the AIP New Zealand AD section.
takeoff and landing techniques are always
At non-published airstrips distances should be
paced out. Pace length should be established
used when operating out of airstrips
where the distance available is a factor.
Consult the Flight Manual, or an instructor,
accurately – or deliberately underestimated.
if you are unsure as to what technique
If you expect to use a strip frequently, you
should be used for a particular aircraft.
should ensure that the length is measured
Consider undertaking some dual short-field
accurately (for example, by using a rope of
takeoff and landing revision.
known length).
17
Speed Control
Decision Points
The speed at which you lift off is very
You should always nominate a decision
important with regard to achieving the
point where you will abandon the takeoff
best takeoff performance from the aircraft
or discontinue the approach if things are
– particularly when runway length is a
not going as expected.
significant factor. Likewise, letting the
For takeoff, this is the point at which there
aircraft accelerate in ground effect to best
is sufficient distance available to safely
angle-of-climb speed is also critical.
stop the aircraft should it accelerate slower
For landing, correct speeds for the prevailing
than expected or suffer a power loss.
conditions are obviously important.
This is particularly important for multiengine aircraft.
Photo courtesy of Kaye Nairn
Arrive too fast and you will use up more
runway, too slow on approach and you may
For landing, the decision point should be
stall and not arrive on the runway at all.
a height where there is sufficient room to
18
effect a safe go-around if you are not happy
Contingencies
with the approach. An important factor
Even after having worked out your aircraft’s
here, and one that is often overlooked by
takeoff or landing performance, it is prudent
pilots, is the assessment of groundspeed
to add a contingency to allow for other
while on approach. A check of the windsock
factors that you may have overlooked.
and an estimate of whether your ground-
For instance, the engine may not be
speed is about what you would expect for
performing as well as it used to, the brakes
your airspeed when on short final is good
may be dragging slightly, the propeller may
practice. Any tailwind component very
be less efficient than it used to be, you might
significantly increases the landing distance,
encounter a lull or shift in the wind, etc.
so a go-around is usually the best course
Where takeoff and landing distances are
of action should this be the case.
looking marginal, we suggest that you always
factor a contingency of at least 10 percent
into your calculations.
19
Determining Performance
The following section gives three ways of ensuring adequate takeoff
and landing performance for private operations.
Group Rating System
The Group Rating system allows for runway
length, slope and surface, with a generous
What Is It?
allowance for ambient conditions, and it
Every light aircraft in New Zealand has been
assumes that the operation is conducted
(and still is) assigned a group rating number
into wind using recommended short-field
from 1 to 8 – based on its takeoff and
techniques. The system can’t take into
landing performance at maximum weight
account specific conditions on the day,
(1 = excellent performance and 8 = poor
so the aircraft Group Rating number
performance). Runways that are published
allocated is conservative for private
in the AIP New Zealand AD section are
operations. However, if ambient conditions
also assigned a group rating number based
differ significantly from ISA in a way that
on their characteristics (1 = short distance
will reduce performance, and the airstrip is
available and 8 = long distance available).
sloping, it would be wise to use a P-chart
20
AIP New Zealand
NZGS AD 2 - 52.1
GISBORNE
Certificated Aerodrome 1NM W of Gisborne
Not for operational use
NZGS
OPERATIONAL DATA (1)
RWY
RWY
SFC
Strength
Gp
Slope
ASDA
14
32
1310
B
PCN 20
F/B/Y/T
8
0.07U
0.07D
14
14
B
PCN 20
F/B/Y/T
7
6
0.07U
32
32
0.07D
Take-off distance
1:20
1:25
1:30
1:40
1:50
1371
777
EXTENSION CLOSED
LDG
1:62.5 DIST
1371
1270
1310
868
B
PCN 20
F/B/Y/T
6
7
14
14
Gr
ESWL
1600
4
6
0.08U
32
32
Gr
ESWL
1600
6
4
0.08D
03
21
Gr
ESWL
5700
8
0.05U
0.05D
1042
1170
1170
1042
09
27
Gr
ESWL
9080
8
0.1U
0.1D
1039
1173
1173
1039
868
EXTENSION CLOSED
551
750
777
750
551
MINIMA
Figure
2
IFR Take-off
RWY
Day
Night
14/32
300–1500
300–1500
03/21
600–1500
600
1500
or the Flight Manual to determine
takeoff
09/27
NA runways with a group rating of 6 or
from
and landing distances.
greater. If the runway group rating is less
The group number of your aircraft can be
than 6 it may still be safe to operate under
found in the front of its Flight Manual.
favourable conditions, but you would need
The runway group rating number can
to work out the distances required for the
be found in the table at the top of each
prevailing conditions using one of the other
aerodrome operational data page in the
two methods.
AIP New Zealand AD section.
Note that some runways may in fact have
(continued)
more than one group number assigned to
How Does It Work?
them because of differences in the available
Using the group rating system is very
takeoff and landing distance, for example
simple. For example, if your aircraft has
Gisborne (see Figure 2).
a group rating of 6, it is safe to operate
Effective: 24 SEP 09
GISBORNE
21
E Civil Aviation Authority
OPERATIONAL DATA (1)
P-Charts
What Are They?
Use of a Performance chart (P-chart) is
P-charts are graphs developed from
another acceptable method (which is more
manufacturer’s test data. They apply various
precise than the group rating system)
factors, including density altitude, type of
for determining takeoff and landing
operation, runway surface, runway slope
performance.
and wind to readily determine takeoff
and landing distances for a particular set
Photo courtesy of Jack Stanton
of conditions.
22
The CAA no longer (as of 1 April 1997)
P-chart, it is important to know how to use it
includes a P-chart when it issues a
and to understand what is being allowed for.
Flight Manual for an aircraft. But for the
majority of light aircraft in New Zealand
Examples
the P-chart remains a very practical
The following example gives guidance on
method of determining takeoff and landing
how to best use a P-chart. (Note that at the
performance and can be completed with
bottom of the P-chart there is a tracking
ease. If your aircraft Flight Manual has a
depiction on how to work from box to box.)
23
Takeoff Distance Example
Determining Density Altitude
The red line in Figure 3 relates to the data
The first thing we need to do is to calculate
supplied below and the blue line provides
the airstrip’s density altitude.
a comparison for ‘standard’ conditions.
To do this we must determine the pressure
Note that all takeoff distances are to a
altitude of the airstrip and then correct
height of 50 feet, at which point a speed of
it for temperature by using the ambient
1.2 Vs (where Vs is the stall speed for the
temperature of the day (26˚C in this case).
chosen configuration) is assumed to have
This is an area that many pilots seem to
been achieved. Landing distances are also
have difficulty with.
all from a height of 50 feet with a speed of
The easiest way to determine pressure
1.3 Vs when passing through that height.
altitude, if we are sitting in our aircraft,
The distances given for private operations
is to set the sub-scale on the altimeter to
represent the minimum distance acceptable,
1013.2 hPa. The altimeter will then read
and pilots should carefully review all factors
the pressure altitude of the aerodrome.
(and other options) before landing at or
taking off from an aerodrome with only the
Alternatively, knowing that 1013.2 hPa is
bare minimum distance available.
ISA pressure at sea level, we calculate the
difference from today’s QNH (sea level
Type of Operation – Private
pressure), which is 997 hPa. This is 16 hPa
Aircraft – Cessna 172P
below 1013.2 hPa, and as each hectopascal
Max all up weight – 1089 kg
equals approximately 30 feet, this equates
to 480 feet. We must now apply this
QNH – 997 hPa
correcting figure to our aerodrome elevation
Temperature – 26˚C
of 1320 feet. Do we add it or subtract it?
Wind – 050˚M/15 knots
Because the pressure today is lower than
Aerodrome elevation – 1320 feet amsl
standard (pressure decreases with altitude,
997 hPa being found at 480 feet amsl
Runway – 020˚M
on a standard day) we add the figure to
Surface – grass
aerodrome elevation, arriving at a pressure
Length – 730 metres
altitude of 1800 feet.
Slope – 1% up
24
25
Figure 3
0
1000
2000
3000
4000
DENSITY
ALTITUDE
Density Altitude Graph
Surface
Now we start at the box for determining
From this point we track vertically up
density altitude which can be found at the
into the next box, until we meet the line
bottom left of the chart. We enter the graph
“Private – Grass – Day”.
at the top with the ambient temperature
of 26˚C, and track vertically down that line
Slope
until we meet the imaginary angled pressure
We then move horizontally to the next
altitude line for 1800 feet (ie, a point just
box going through to the zero line. (This is
under the angled 2000-foot line).
most important – always go to the zero
line in the last two boxes.) We then track
(For our exercise, we don’t need to worry
parallel to the curved lines until we reach
about the angled temperature lines marked
the 1 percent up line.
“ISA+10” etc, which depict the ISA drop-off
in temperature with altitude.)
Wind
From that point we exit the box horizontally
The headwind component must now
to the right. A scale is not usually marked
be determined because the wind is not
on the righthand side of the box, but we
straight down the runway. The crosswind
have shown the density altitude figures in
component graph in the Flight Manual can
colour on our example to give you a better
be used to calculate this (see figure 4).
appreciation of what you are working out.
The headwind component in this case is
(You will note that, although the aerodrome
13 knots.
elevation in our example is only 1320 feet,
Now we move horizontally to the zero
the density altitude under the prevailing
line of the wind box. Using the headwind
conditions is 3500 feet – quite a significant
component of 13 knots track parallel to
difference.)
the curved line until we reach the 13-knot
headwind line. From this point, we exit
Weight
horizontally to the right of the box, where
Continue horizontally into the next box until
we can read off the distance required
we meet the weight line of 1089 kilograms
for takeoff.
(ie, the maximum). You will notice that the
only variable on the chart that the pilot has
In this example nearly 700 metres is
any control over is the weight of the aircraft.
required to reach a height of 50 feet.
Bearing this in mind, the graphs can be
As the runway in this example is 730 metres
used to work out a safe operating weight
long, we should be able to take off safely
on marginal runways.
(but remember this is for short dry grass).
26
Figure 4 Wind Components
EXAMPLE:
FLIGHT
PATH
60
0˚
10˚
Wind Speed
Angle between wind
direction and flight path
10 Knots
Headwind component
Crosswind component
9.5 Knots
3.5 Knots
20˚
20˚
50
IN
W
30˚
D
AT
FL
IG
HT
P
50˚
N
AN
D
50
S
OT
KN
H
60
–
60˚
40
W
EE
N
W
IN
D
DI
RE
CT
IO
30
30
70˚
GL
EB
ET
20
AN
HEADWIND COMPONENT – KNOTS
D
EE
40
SP
40˚
20
10
80˚
10
0
90˚
-10
-20
100˚
180˚ 170˚ 160˚ 150˚ 140˚
0
10
130˚
120˚
20
30
40
CROSSWIND COMPONENT – KNOTS
27
110˚
50
60
Landing Distance Example
as engine performance is not a critical factor
Now work through the landing example
(unless a go-around becomes necessary).
At very high density altitudes, however,
provided (see Figure 5) using the same
the resulting higher true airspeed (TAS)
aircraft, aerodrome and weather conditions
should be borne in mind in relation to the
as above by following the red line.
approach and landing, as should the reduced
Note that aerodrome elevation is used rather
power available for a go-around.
than density altitude in this calculation,
You will also note that the slope corrections
are reversed from the takeoff situation;
an uphill slope on landing will decrease the
landing distance and vice versa.
28
29
Figure 5
Aircraft Flight Manual
allowed for manually and added to the
Takeoff and landing performance graphs/
basic takeoff or landing distance as a
tables in aircraft Flight Manuals vary from
percentage value.
manufacturer to manufacturer.
AC91-3 suggests that takeoff and landing
Usually they do not allow for as many
distances derived from the aircraft flight
variables as P-charts.
manual should be corrected for variation
in runway surface and slope by applying
Each graph or table will normally be
the factors in Figures 6 and 7.
formulated for standard conditions
(ie a level, dry, paved surface in nil wind
If your aircraft Flight Manual has a
with the aircraft configured for a short-
P-chart, we suggest that, in most cases,
field takeoff or landing) and allows for
it is preferable that you use it over other
variations in weight, pressure altitude,
Flight Manual data – particularly if it is an
and temperature only. For tables, these
old Flight Manual, some of which tend to
variables are usually given over rather
be less comprehensive than their modern
a broad range, eg temperature in bands
counterparts. Some manufactures’ Flight
of 10˚C and pressure altitude in bands
Manual data can also, at times, tend to be
of 1000 feet. Other variables, such as
optimistic rather than conservative about
wind and type of surface, have to be
their aircraft’s performance.
30
AC91-3
AC91-3
ensures that you
the capability
Aircraft flight
manual
thishave
ensures
that you
4.
Aircraftdata
flight manualthis
data
clear any obstacles close
theobstacles
runway end
cleartoany
cl
4.1
For calculating
aircraft
performance,
4.1
For calculating aircraft performance,
the aircraft manufacturer
has
supplied
4.3
In
addition
you
should
correct
the
the aircraft manufacturer has supplied
4.3
In addition yota
performance data performance
in the aircraft data
flightinmanual.
off distance
from
airc
the aircraft flight
manual.to 50 feet
offderived
distance
to the
50 feet
This data allows you to calculate the take-off
manual for–
This data allows you to calculate flight
the take-off
flight manual for–
and landing distances with a correction for
and landing distances with a correction for
(a) other than a paved runway surface
density altitude at various weights and for the
(a) other than a p
density altitude at various weights and forapplying
the
the factors in Table 1; and
surface wind. The manufacturer does not
applying the f
surface
wind. the
Theeffect
manufacturer
does not
provide you with data
to calculate
of
provide
you runway
with data
to calculate the (b)
effect
of slope by applying the factor
runway
runway slope or the
different
surface
(b) runway
slope
runway slope or the different runway surface
Table 2 up to a maximum
of 3%
slo
types.
Table 2 up to
types.
4.2
You should use the flight manual data
4.2
You should
to determine the take-off
distance
to 50use
feet the
as flight manual data
determine
the take-off distance to 50 feet as
Table 1. Runwayto
surface
factors
Table 1. Runway surface factors
SURFACE
TAKE-OFF
LANDING
SURFACE
TAKE-OFF FACTOR
LANDING
TYPE
DISTANCE
FACTOR DISTANCE
TYPE
DISTANCE FACTOR DISTANCE FACTOR
x 1.00
x 1.00
Paved
x 1.00
x 1.00
Paved
Figure 6
x 1.00
x 1.05
Coral
Runway surface
x 1.00
x 1.05
Coral
x 1.05
x 1.08
Metal
factors
x 1.05
x 1.08
Metal
x 1.16
Rolled earth x 1.08
4.
Grass
Rolled earth
x 1.14
Grass
x 1.08
x 1.18
x 1.16
x 1.14
x 1.18
Table 2. Runway slope factors
DIRECTION OF
SLOPE
Figure 7
Runway slope
factors
Uphill
Table 2. Runway slope factors
% OF SLOPE
TAKE-OFF
DISTANCE
DIRECTION OF %CORRECTION
OF SLOPE
SLOPE
1
+5%
1
+10%
+5% -10%
-5%
2
+15%
+10%-15%
-10%
1
-5%
3
+15%+5%
-15%
2
-10%
1
-5% +10%
+5%
3 Downhill
-15%
2
-10% +15%
+10%
-15%
+15%
2
3
Downhill
LANDING DISTANCE
CORRECTION
LANDING DIS
TAKE-OFF
CORRECT
DISTANCE
CORRECTION
-5%
Uphill
3
For slopes expressed to a decimal point, the correction is 0.5% distance for each 0.1% slope. For example, f
runway slope of 1.6% the correction factor is 8%.
31
For slopes expressed to a decimal point, the correction is 0.5% distance for each 0.1
runway slope of 1.6% the correction factor is 8%.
Air Transport Operations
There are also specific runway surface and
slope correction factors to apply.
If you are operating a light aircraft on
Air Transport or Commercial Transport
Part 135 requires you to use Flight Manual
operations, there are specific performance
data to determine takeoff and landing
requirements that must be met in CAR Part
performance. This may include the use of
135 Air Operations – Helicopters and Small
P-charts but the group rating system is not
Aeroplanes, Subpart D.
acceptable for air transport operations.
For example, the takeoff distance required
See Advisory Circular 119-3 Air Operator
must not exceed 85 percent of the takeoff
Certification – Part 135 Operations for details
run available. You must take account of
on how to compile a P-chart and apply the
not more than 50 percent of the reported
applicable Air Transport factors to your aircraft
headwind (or not less than 150 percent of
Flight Manual performance data.
the reported tailwind, as the case may be).
32
Know Your Aircraft
when it comes to deciding whether such
It is useful to work out, and remember, the
calculations are necessary – it is better
takeoff and landing distances required for
to be safe than sorry.
your aircraft in ISA conditions at sea level,
If you own your own aircraft, you might
with nil slope, and nil wind on a sealed
like to consider actually confirming what
runway. This can serve as a basis for
distance it will takeoff and land in under
determining whether it is necessary to carry
these conditions – get to know your
out performance calculations in any given
own aircraft.
situation. Always err on the side of caution
33
Conclusion
Takeoff and landing are both high-risk
phases of flight. The more that we can
do as pilots to minimise these risks,
especially when operating out of a short
airstrip in an underpowered aircraft,
4. 1973 feet is required.
the safer we will be.
Yes, I could land there at this weight.
If takeoff or landing performance is ever
3. Maximum weight would be 1045 kg.
doubtful, then taking the time to apply
2. Yes – 460 metres would be required.
basic performance calculations is a
prudent thing to do and takes the
Landing – 460 metres.
‘she’ll be right’ out of the situation.
1. Takeoff – 570 metres.
Make performance calculations part of
problems from page 35:
your pre-flight planning if you suspect
Answers to aircraft performance
things might be tight.
34
Performance Questions
Now that you have seen how to use a P-chart, try these problems by using the chart
provided in the original example above (answers on page 34):
grass runway, in my private Group 6
1. A private flight, C172P, aircraft weight
1089 kg, QNH 1020 hPa, temperature
Cessna 172P. Assume standard pressure,
20˚C, aerodrome elevation 400 feet,
a temperature of 25˚C, and nil wind.
slope nil, grass/day, wind 250˚M at
The runway is 575 metres long with
5 knots, runway 22.
no slope.
What would be the maximum allowable
What takeoff and landing distances
weight for a safe takeoff under these
are required?
conditions? Could I land there at
2. An air transport flight, C172P,
this weight?
aircraft weight 1089 kg, QNH 997
4. A private flight, C172P, aircraft weight
hPa, temperature 26˚C, aerodrome
2400 lbs, QNH 1013 hPa, temperature
elevation 1700 feet, slope 1 percent
25˚C, aerodrome elevation 1000 feet,
down, paved/day, wind 150˚M at
nil slope, grass/day, wind 220˚M at
10 knots, runway 18 (520 metres).
10 knots, runway 22.
Can I safely land on runway 18 in these
Use the Flight Manual data provided below,
conditions?
and any other corrective factors required,
to calculate the takeoff distance to 50 feet
3. I would like to fly into Kaikoura
under these conditions.
(elevation 19 feet), which has a Group 4
0˚c
Takeoff
Speed KIAS
Weight
LBS
Lift off
AT 50 ft
2400
51
56
Notes:
10˚c
20˚c
30˚c
Press
Alt ft
Ground Total ft Ground Total ft Ground Total ft Ground Total ft
roll
to clear
roll
to clear
roll
to clear
roll
to clear
ft
50 ft OBS
ft
50 ft OBS
ft
50 ft OBS
ft
50 ft OBS
S.L.
1000
2000
3000
4000
5000
6000
7000
8000
795
875
960
1055
1165
1285
1425
1580
1755
1460
1605
1770
1960
2185
2445
2755
3140
3615
860
940
1035
1140
1260
1390
1540
1710
1905
1570
1725
1910
2120
2365
2660
3015
3450
4015
925
1015
1115
1230
1355
1500
1665
1850
2060
1685
1860
2060
2295
2570
2895
3300
3805
4480
1. Decrease distances 10 percent for each 9 knots of headwind.
2. For operation on a dry, grass runway, increase distances by 15 percent.
35
995
1090
1200
1325
1465
1620
1800
2000
----
1810
2000
2220
2480
2790
3160
3620
4220
----
PO Box 3555,
Wellington 6140
Tel: +64 4 560 9400
Fax: +64 4 569 2024
Email: info@caa.govt.nz
Takeoff and Landing Performance was published in January 2011.
See our web site, www.caa.govt.nz, for details of more safety publications.