1. Performance
Chapter 11

2. Aim
To determine aeroplane performance using flight manual data

3. Objectives Define Performance State terms and definitions
State factors affecting take-off and landing performance
Calculate Pressure and Density altitudes
Calculate take-off performance
Calculate landing performance

4. Background Define the following Max take-off weight (MTOW) –
Max landing weight (MLW) -
Basic empty weight (BEW) -
Centre of Gravity (CoG) -
Maximum permitted take-off weight
Maximum permitted landing weight
Weight of aircraft without any payload, includes un-useable fuel and full oil
Point where all the weight is said to act. Also the point about which the aircraft pivots

5. 1. Define Performance Definition
Understanding performance data allows us to make practical use of the airplane’s capabilities and limitations

6. 2. Terms and Definitions
Take-Off Distance Required (TODR) - Distance required to take-off and reach a screen height (usually 50ft) above the runway at take-off safety speed
Take-Off Run Required (TORR) - Actual Ground Run Required
Take-Off Safety Speed (TOSS) - Speed which gives an adequate margin above the stall speed in the take-off configuration. Must not be less than 1.2Vs
Screen Height
TORR
TODR

7. 2. Terms and Definitions
Clearway – Defined area on the ground or over water that is free of obstacles, over which an aircraft may make its initial climb
Take-Off Run Available (TORA) – Length of the runway available and suitable for the ground run of an aircraft taking off
Take-Off Distance Available (TODA) – Length of take-off run available plus any clear way
Screen Height
Clearway
TORA
TODA

8. 2. Terms and Definitions
Stopway – Defined area on the ground at the end of a runway suitable area in which an aircraft may stop in an emergency
Accelerate Stop Distance Available (ASDA) – Distance specified as being the effective length available for use by an aircraft executing an aborted take-off, including any Stopway
Stopway
ASDA

9. 2. Terms and Definitions
Landing Distance Required (LDR) - Distance required to land from a height of 50ft above the threshold to where the aircraft comes to a complete stop
Landing Run Required (LRR) - Actual Ground Roll Required
Landing Distance Available (LDA) – Length of runway suitable for the ground roll of an aircraft beginning at the threshold or displaced threshold
50’
LRR
LDR
LDA

10. 3. Factors Affecting Perf.
Take-Off
The pilot in command of an aircraft must ensure the TODR does not exceed the TODA
When calculating TODR the PIC must take into account:
TORA
Wind component
Pressure Altitude
Temperature
Aircraft Weight
Slope
Surface

11. 3. Factors Affecting Perf.
Take-Off - Wind
Nil Wind

12. 3. Factors Affecting Perf.
Take-Off - Wind
Head Wind

13. 3. Factors Affecting Perf.
Take-Off - Wind
Tail Wind

14. 3. Factors Affecting Perf.
Take-Off - Wind
Head Wind
Nil Wind
Tail Wind

15. 3. Factors Affecting Perf.
Take-Off
Factor
Wind
Altitude
Temp.
Weight
Slope
Flaps
Surface
Reason
Affect on TODR
H/W – T/W –
Groundspeed changed
Lower engine efficiency, greater TAS required
Increase in temperature decreases air density giving a lower performance
More inertia
Need to accelerate uphill
Some aircraft have take-off flap settings, allowing then to get airborne faster but reducing their overall climb performance
Friction

16. 3. Factors Affecting Perf.
Landing
The pilot in command of an aircraft must ensure the LDR does not exceed the LDA
When calculating LDR the PIC must take into account:
LDA
Wind
Elevation/Altitude
Aircraft weight
Slope
Surface

17. 3. Factors Affecting Perf.
Landing - Wind
Nil Wind

18. 3. Factors Affecting Perf.
Landing - Wind
Head Wind

19. 3. Factors Affecting Perf.
Landing - Wind
Tail Wind

20. 3. Factors Affecting Perf.
Landing - Wind
Head Wind
Nil Wind
Tail Wind

21. 3. Factors Affecting Perf.
Landing
Factor Wind Altitude Weight Slope Flaps Surface
Reason
Affect on LDR
H/W – T/W –
Groundspeed changed
Greater TAS
Increased momentum
Upslope helps deceleration
Lower approach speed, Increase in drag
Bitumen increases braking efficiency

22. 3. Factors Affecting Perf.
CAO – Take-Off
Subject to paragraph 6.3, the take-off distance required is the distance to accelerate from a standing start with all engines operating and to achieve take-off safety speed at a height of 50 feet above the take-off surface, multiplied by the following factors:
(a) 1.15 for aeroplanes with maximum take-off weights of kg or less;
(b) 1.25 for aeroplanes with maximum take-off weights of kg or greater; or
(c) for aeroplanes with maximum take-off weights between kg and kg, a factor derived by linear interpolation between 1.15 and 1.25 according to the maximum take-off weight of the aeroplane.

23. 3. Factors Affecting Perf.
CAO Landing
Subject to paragraphs 10.3 and 10.4, an aeroplane must not land unless the landing distance available is equal to or greater than the distance required to bring the aeroplane to a complete stop or, in the case of aeroplanes operated on water, to a speed of 3 knots, following an approach to land at a speed not less than 1.3VS maintained to within 50 feet of the landing surface. This distance is to be measured from the point where the aeroplane first reaches a height of 50 feet above the landing surface and must be multiplied by the following factors:
(a) 1.15 for aeroplanes with maximum take-off weights of kg or less;
(b) 1.43 for aeroplanes with maximum take-off weights of kg or greater;
(c) for aeroplanes with maximum take-off weights between kg and 4500 kg, a factor derived by linear interpolation between 1.15 and 1.43 according to the maximum take-off weight of the aeroplane.

24. READ THE CONDITIONS ON THE CHART
3. Factors Affecting Perf.
CAO
Some tables and charts will factor this in.
READ THE CONDITIONS ON THE CHART

25. 4. Pressure and Density Altitude
International Standard Atmosphere (ISA)
ISA provides a yardstick against which we can measure the effects of changing atmospheric conditions against performance figures produced by the aircraft manufacturer
Standard ISA conditions at sea level are:
QNH 1013 hPa
Lapse rate of 1 hPa per 30ft
Temperature 15⁰C
Lapse rate of 2⁰C per 1000ft
Density Kg/M3

26. 4. Pressure and Density Altitude
Pressure Altitude
Pressure altitude is altitude corrected for pressure deviations from ISA
If our QNH is greater than ISA our pressure altitude will be less than our actual altitude and the aircraft will perform better
If our QNH is less than ISA our pressure altitude will be greater than our actual altitude and the aircraft will perform worse
To calculate pressure altitude we must:
Determine pressure variation from ISA
Multiply variation by the pressure lapse rate, 30ft per 1 hPa
Apply the variation to the aerodrome elevation
If our QNH is greater than ISA our pressure altitude will be less than our actual altitude
If our QNH is less than ISA our pressure altitude will be greater than our actual altitude

27. 4. Pressure and Density Altitude
Pressure Altitude
For Example:
Elevation is 650ft
QNH is 1020 hPa
Temperature is 30⁰C
What is the pressure altitude?
Determine pressure variation from ISA
1013 hPa – 1020 hPa = -7hPa
Multiply variation by the pressure lapse rate, 30ft per 1 hPa
-7 hPa x 30ft = -210ft
Apply the variation to the aerodrome altitude
Since QNH is greater than ISA, pressure altitude will be lower
650ft – 210ft = 440ft

28. 4. Pressure and Density Altitude
Density altitude is the altitude which has the same density as ISA standard
If our density altitude is less than ISA the aircraft will perform better
If our density altitude is greater than ISA the aircraft will perform worse
To calculate density altitude we must:
Determine pressure altitude
Determine temperature variation from ISA at the pressure altitude
Multiply variation by the lapse rate, 120ft per 1⁰C
Apply the variation to the pressure altitude
If our temperature is greater than ISA our density altitude will be greater than our actual altitude
If our temperature is less than ISA our density altitude will be less than our actual altitude

29. 4. Pressure and Density Altitude
For Example:
Pressure altitude is 4000ft
QNH is 1020 hPa
Temperature is 22⁰C
What is the density altitude?
Determine temperature variation from ISA at the pressure altitude
15 ⁰C - (2x4)= 7 ⁰C
Multiply variation by the lapse rate, 120ft per 1⁰C
22⁰C - 7 ⁰C = 15 ⁰C x 120ft = 3300ft
Apply the variation to the pressure altitude
Because the temperature is greater than ISA our density altitude will be greater than our actual altitude
4000ft ft = 7300ft

30. 5. Calculate Take-Off Perf.
Take Off Performance – Typical Cessna Chart
For Example, calculate the Maximum Take-Off Weight for the following conditions:
Pressure altitude 4000ft
Temperature 25⁰C
Take off Distance Available 800m
Surface long dry grass
No slope
15kt Headwind

31. 5. Calculate Take-Off Perf.
Take Off Performance – Typical Cessna Chart
Method:
Enter the chart with 4000’ on the pressure altitude scale and plot a horizontal line to intersect 25⁰C
From this point plot a vertical line to the TODA of 800m. Also from the intersection of the climb weight limit line draw a horizontal line to the right. This gives us the climb weight limit of 1060kg

32. 5. Calculate Take-Off Perf.
Take Off Performance – Typical Cessna Chart
Method:
From the intersection of the TODA (800m) line plot a horizontal line to the reference line
From the reference line follow the lines in the window to the “Long dry grass” line. Plot a horizontal line from here into the slope graph

33. 5. Calculate Take-Off Perf.
Take Off Performance – Typical Cessna Chart
Method:
From the intersection of the horizontal line and the “Level” line plot a vertical line down into the wind graph to intersect 15kt headwind
From this point plot a horizontal line to the Take Off Weight scale. This gives us the runway performance weight limit of 1000kg

34. 5. Calculate Take-Off Perf.
Take Off Performance – Typical Cessna Chart
Method:
The Maximum Take Off Weight is the lesser of the climb weight limit (1060kg) and the runway performance limit (1000kg)

35. 5. Calculate Take-Off Perf.
Take Off Performance – Typical Piper Chart
For Example, calculate the Take-Off Distance Required for the following conditions:
Pressure altitude 2000ft
Temperature 20⁰C
Surface Long dry grass
2% Down slope
5kt Headwind
Take-Off Weight 1000kg

36. 5. Calculate Take-Off Perf.
Take Off Performance – Typical Piper Chart
Method:
Enter the chart with 25⁰C on the Temperature scale and plot a vertical line up to the Pressure altitude of 2000’. Also check the climb weight limit
From this point plot a horizontal line to the surface reference line. Follow the guide lines to the long dry grass line then proceed horizontally to the slope reference line

37. 5. Calculate Take-Off Perf.
Take Off Performance – Typical Piper Chart
Method:
Follow the guide lines to the 2% down slope line then proceed horizontally to the wind reference line
Follow the guide lines to the 5kt headwind line then proceed horizontally to the take off weight of 1000kg

38. 5. Calculate Take-Off Perf.
Take Off Performance – Typical Piper Chart
Method:
Follow the guide lines to determine the Take-Off Distance Required 750m

39. 5. Calculate Landing Perf.
Landing Performance – Typical Cessna Chart
For Example, calculate the Landing Distance Required and Maximum Landing Weight for the following conditions:
Pressure altitude 7000ft
Temperature 15⁰C
No slope
10kt Headwind

40. 5. Calculate Landing Perf.
Landing Performance – Typical Cessna Chart
Method:
Enter the chart with 7000’ on the pressure altitude scale and plot a horizontal line to intersect 15⁰C
From this point plot a vertical line into the Landing Distance Required Window

41. 5. Calculate Landing Perf.
Landing Performance – Typical Cessna Chart
Method:
Enter the chart again from the wind component of 10kts and plot a vertical line up to the slope, in this case level
From this point plot a horizontal line to intersect the vertical line already in the Landing Distance Required window

42. 5. Calculate Landing Perf.
Landing Performance – Typical Cessna Chart
Method:
Follow the guide lines to the left to determine the Landing Distance Required 550m
We also need to check the climb weight limit – in case of a Go-Around – In the climb weight limit window plot a horizontal line from pressure height to the reference line then straight down to read the climb weight limit of 910kg

43. 5. Calculate Take-Off Perf.
Landing Performance – Typical Piper Chart
For Example, calculate the Landing Distance Required for the following conditions:
Pressure altitude 4000ft
Temperature 30⁰C
2% Down slope
10kt Headwind

44. 5. Calculate Take-Off Perf.
Landing Performance – Typical Piper Chart
For Example, calculate the Landing Distance Required for the following conditions:
Pressure altitude 4000ft
Temperature 30⁰C
2% Down slope
10kt Headwind

45. 5. Calculate Take-Off Perf.
Take Off Performance – Typical Piper Chart
Method:
Enter the chart with 30⁰C on the Temperature scale and plot a vertical line up to the Pressure altitude of 4000’. Also check the climb weight limit
From this point plot a horizontal line to the slope reference line. Follow the guide lines to the 2% down slope line then horizontally across to the wind reference line
No climb weight limit with a pressure alt. of 4000’

46. 5. Calculate Take-Off Perf.
Take Off Performance – Typical Piper Chart
Method:
Follow the guide lines to the 10kt headwind line then proceeded horizontally to read the Landing Distance Required of 690m
No climb weight limit with a pressure alt. of 4000’

47. Questions?