1. Transportation PLANNING and management AIRPORT ENGINEERING lec#02By
Engr. Ghulam Hussain
Lecturer
Civil Engineering Department
The University Of Lahore

2. Runway
According to ICAO a runway is "A defined rectangular area on a land aerodrome prepared for the landing and take-off of aircraft." Runways may be a man-made surface (often asphalt, concrete, or a mixture of both) or a natural surface (grass, dirt, gravel, ice or salt).

3. Runway configuartion Single runway Parallel runways Open-V runways
Intersecting runways

5. Reasons for choosing one configuration over another is all about the prevailing winds, noise pollution, and local restrictions, among other.

6. Runway Length Analysis

7. Understanding aircraft weight & its characteristics

8. Aircraft Mass Definitions
There are several important aircraft operational characteristics to know about the aircraft mass.
Aircraft mass expenditures are significant and thus need to be accounted for in the air vehicle runway length analysis.
OEW = operating empty weight (or mass) is the weight (or mass) of the aircraft without fuel and payload (just the pilots and empty seats)
MTOW = maximum takeoff operating weight (or mass) - structurally the maximum demonstrated mass at takeoff for safe flight
(excludes run-up fuel and includes OEW, fuel & Payload). Longer trips requires more fuel with less payload

9. Aircraft Mass Definitions (II)
MALW = maximum allowable landing weight (or mass) is the maximum demonstrated landing weight (or mass) to keep the landing gear intact at maximum sink rate (vertical speed)
MSPW = maximum structural payload weight (or mass) is the maximum demonstrated payload to be carried without stressing the aircraft fuselage
MZFW = maximum zero fuel weight (or mass) is the sum of the OEW and the MSPW
MTW = maximum taxi weight (or mass) of the maximum demonstrated weight (or mass) for ground maneuvering. Usually slightly more than MTOW (includes run-up fuel).

10. Operational definitions
DTW = desired takeoff weight (or mass) is the weight of the aircraft considering fuel (includes reserve), payload and OEW to complete a given stage length (trip distance)
DTW = PYL + OEW + FW (trip fuel reserve)
where:
PYL is the payload carried (passengers and cargo)
OEW is the operating empty weight
FW is the fuel weight to be carried (usually includes reserve fuel)

11. Length of runway
Selecting the length of runway is perhaps the important decision which must be made in the planning of landing area.
Length of runway mainly depends on
The type of aircraft
Its payload
Trip length (fuel weight)
Altitude and temperature at the airport
Safety regulations

12. Basic runway length
It is the length of runway under the following assumed condition at the airport:
Airport altitude at sea level
Temperature at airport is standard (150 c)
Runway is leveled in the longitudinal direction
No wind is blowing on runway
Runway surface is dry
Aircraft is loaded at its full loading capacity
Corrections to basic runway length

13. Typical runway lengths
Aircraft Type
Takeoff (ft.)
Landing (ft.)
B B
10,500
6,150
DC-10-30
10,490
5,960
Concorde
10,280
8,000 B
10,080
4,800
A300 B4
8,740
5,590 B
6,550
4,290
DC-9-50
7,880
4,680 F
5,490
3,540
F27-500
5,470
3,290
SD3-30
3,900
3,400

14. Terms used for runway length
FS = full strength pavement distance
CL = clearway distance
SW = stop way distance
FL = field length (FS+SW+CL)
LOD = lift off distance
TOR = takeoff run
TOD = takeoff distance
LD = landing distance
SD = stopping distance
D35 = distance to clear an 11 m (35 ft.) obstacle
DAS = distance to accelerate and stop (ASD)

15. Runway Components

16. Runway design concepts
Runway in future discussion refers to full strength pavement (FS) - Support the full weight of the aircraft
For turbine aircraft the regulation do not requires FS for the entire Take-off Distance (TOD), while for piston aircraft requires FS for entire TOD
Runway Field Length (FL) have three basic components
Full strength pavement (FS)
Clearways (CL)
Stopways (SW)

17. Runway design concepts
Clearway (CL)
Rectangular area beyond the runway not less than 500 ft. wide and not longer than 1000 ft.
Extends from end of runway with a slope not exceeding 1.25 percent above which no object protrude except for the threshold lights on two sides of the runway (not higher than 26 inches)
Allowing aircraft to climb safely to clear an imaginary 11 m (35 ft. obstacle)

18. Runway design concepts
Stopway (SW)
Area beyond runway, width not less than runway
Paved surface that allows aircraft to stop in situation of abandoned takeoff (engine failure in turbine powered is not very common)
Permit use of lesser strength pavement for turbine powered, while for piston aircraft requires FS for entire SW

19. Runway requirtements
The following cases are considered for determining the basic runway length
Normal takeoff (all engines working fine)
Engine-out takeoff condition
Continued takeoff
Aborted takeoff
Landing
The cases which works out the longest runway length is finally adopted

20. Normal landing case
The normal landing case requires that an air craft should come to a stop within 60% of the landing distance. The runway of full strength pavement is provided for the entire landing distance.
Runway
Stop
60% of landing distance
Landing distance

21. Landing distance case
The landing distance should be 67% longer than the demonstrated distance to stop an aircraft

22. Normal take-off case
The normal take-off case requires a clearway which is an area beyond the runway and is in alignment with the centre line of runway.
The width of clearway is not <150m and is kept free form obstruction.
The clearway ground area or any object on it should not protrude a plane inclined upward at a slope of 1.25% from the runway.

23. Normal Takeoff Case
clearway

24. Clearway ≤ ½ of this distance
10.5m height
Lift-off distance
115% of Lift-off distance
Distance to 10.5m height
115% of distance to 10.5m height ( take-off distance)
Longitudinal section
Runway
Clearway
Min150m
Plan
Normal Take-off Case

25. Normal Takeoff Case
TOD does not have to be full strength but what is needed that this distance is clear of obstructions.
LOD is lift of distance.
CL is min. 500 ft. wide with a grade less than 1.25 deg.

26. Engine-Out Takeoff Case
Dictated by two scenarios:
Continued takeoff sub case
Actual distance to clear an imaginary 11 m (35 ft) obstacle D35 (with an engine-out)
Aborted or rejected takeoff sub case
Distance to accelerate and stop (DAS)

27. The rules for take off are complicated to say the least
The rules for take off are complicated to say the least. The main issue being what to do if an engine fails while taking off. The procedure begins  with the pilot calculating a speed, known as V1. These calculations take into account temperature, pressure, weight of the aircraft , runway slope and the wind component; all of which effecting the runway length required for take-off.
In the event of an engine failure at or before reaching V1 speed, the pilot must abort the take off by braking the aircraft to a stop by the end of the stopway (see diagram). If there is no engine failure through V1, the pilot raises the nose t at VR ,or rotation speed, and the aircraft  lifts off the runway. Then the  aircraft is flown to  achieve V2, (initial climb out speed), not later than reaching a height of 35 feet.
If an engine out situation occurs after V1, a Clearway( see diagram), beyond the end of the runway, must be available to allow the aircraft to safely continue the climb.. 

28. Engine Out Analysis *
* Decision speed is the speed chosen by the aircraft captain in relation to the respective limitations of the aircraft, the airline operator rules and procedures, runway characteristics and actual meteorological conditions

29. Longitudinal section Min150m Stop Runway way Plan Engine Failure Case
Clearway ≤ ½ of this distance
Decelerated – stop distance
Engine
Failure
10.5m
height
Stop way
Clear way
Lift-off distance
Accelerated stop distance
Distance to 10.5m height ( take-of distance )
Longitudinal section
Runway
Stop
way
Min150m
Plan
Engine Failure Case

30. Required Field Length (FS,FL, SW, CL)
Lengths for the critical aircraft:
Case 1: Normal take-off Case 2: Engine-failure take-off
Case 3: Eng. -failure aborted take-off Case 4: Landing
Final analysis
If both ends of runway are to be used, the field length components (FS, SW and CL) must exist in each direction.

31. Example – Runway Length
Determine the runway length requirements for turbine powered aircraft. Following aircraft performance characteristics are observed:
Normal take off:
Lift off distance = 2100 m
Distance to 11 m height = 2400 m
Engine failure:
Lift of distance = 2460 m
Distance to 11 m height = 2730 m
Engine failure aborted take off:
Accelerate stop distance = 2850 m
Normal landing:
Stop distance = 1500 m

32. Solution: Runway Length (I)
For normal take off:
TOD1 = 1.15 (D351) = 1.15 X 2400 = 2760 m
CL1 = 0.5[TOD (LOD1)] = 0.5[ X 2100]=172.5 m
TOR1 = TOD1 – CL1 = 2760 – = m
For engine failure:
TOD2 = D35.2 = 2730 m
CL2 = 0.5[TOD2 – LOD2] = 0.5[ ] = 135 m
TOR2 = TOD2 – CL2 = 2730 – 135 = 2595 m
For engine failure aborted take off:
DAS = 2850 m
For normal landing:
LD = 1500/0.667 = 2248 m
FL4 = FS4 = LD = 2248 m

33. Solution: Runway Length (II)
The actual runway components are:
FL = max (TOD1,TOD2, DAS, LD)
= max (2760, 2730, 2850, 2500)
= 2850 m
FS = max (TOR1, TOR2, LD)
= max (2587.5, 2595, 2248)
= 2595 m
SW = DAS – max (TOR1, TOR2, LD)
= max (2587.5, 2595, 2248)
= 2850 – 2595
= 255 m
CL = min [(FL – DAS), CL1, CL2)
= min [(2850 – 2850), 172.5, 135)
= min (0, 172.5, 135) = 0

34. Declared distances
Declared distances are the distances which the airport owner declares are available and suitable for:
Take-off run available (TORA)
Take-off distance available (TODA)
Accelerate stop distance available (ASDA)
Landing distance available (LDA)

41. Correction for Elevation, Temperature and Gradient
The basic runway length is for mean sea level
Elevation having standard atmospheric conditions.
For any change in elevation, temperature and gradient for actual site of construction, necessary corrections are to be applied to obtain the length of runway.

42. Correction for Elevation
The air density reduces as the elevation increases, this in turn reduces the lift on the wings of the aircraft and the aircraft requires greater ground speed before aircraft becomes airborne. To achieve greater speed, longer length of runway is required.
Higher altitude requires longer runway length
ICAO recommends that basic runway length should be increased at the rate of 7% per 300m rise in elevation above MSL.

43. Correction for Elevation
Increase the required runway length at a rate of 7% for each 300m (1000ft.) airport elevation above MSL
Elevation factor, Fe = 0.07*E + 1
Where, E is airport elevation above MSL in units of 300m (1000ft.)

44. Correction for Temperature
Higher temperature requires longer runway
Higher temperatures results in lower air density, resulting in lower output of thrust
Increase is not linear with temperature, rate of increase higher at higher temperatures
Standard temperature is 59oF (15oC) at sea level (MSL)
Increase in length is 0.42% to 0.65% per degree Fahrenheit

45. Correction for Temperature
The length corrected for elevation is to be further increased at a rate of 1% for each degree centigrade by which the airport Reference temperature exceeds the Standard temperature at the elevation of airport site.
Reference temperature (T) is defined as:
T1 = Mean of mean Daily Temp. for the hottest month
of the year (Hottest month has the highest mean
daily temperature)
T2 = Mean Maximum Daily Temperature for the same
month

46. Correction for Temperature
Standard Temperature at the airport site can be determined by reducing the standard temperature at MSL (15oC) at a rate of 6.5oC per m or 1.981oC per 1000 ft. rise in the airport elevation above MSL.
Temperature correction factor Ft , is computed through following Equations
Where, E = Airport elevation in 1000 m above MSL

47. Correction for Gradient
Uphill gradient requires more runway length than a down-ward gradient
Increase and decrease in runway length is linear with change in gradient
Length increases by 7-10% for each 1 percent increase in gradient (max gradient is 1.5%)
Average uniform gradient: straight line joining the ends of the runway (no point 5 ft. above the average)
Effective gradient: difference in elevation between the highest and lowest points divided by length of runway

48. Correction for Gradient
The runway length having been corrected for elevation & temperature be further increased at a rate of 10% for each 1% of the runway Effective Gradient (G). The Effective Gradient is the maximum elevation differential of runway center line divided by the total length of runway.
Where, RLmax and RLmin are the reduced levels of highest and lowest points along the runway center line.

49. Surface Wind Greater the head wind, shorter is the runway
The direction of the wind also effects the allowable take-off weight for the airplane
A 5-kn headwind approximately reduces the take-off length by 3 percent
A 5-kn tailwind approximately increases the take-off length by 7 percent.
For planning, no wind is considered if light wind occurs at the airport sight

50. Condition of Runway Surface
Presence of water or slush (reduce braking resistance)
From 0.25 to 0.5 inch, take-off weight must be substantially reduced to overcome the retarding force of water and slush
Velocity at which hydroplaning develops:
For tire pressure range = 120 – 200 psi, Vp ranges from 110 to 140 mph (usual landing and take-off speed)

51. Example
Find out the required length for the airport of reference code 4 D, located at 450 m above mean sea level. The runway effective gradient is 0.5%. The monthly mean maximum and mean daily temperatures of the hottest month of the year are 27oC and 18oC, respectively.
Solution:
Field length = 1800 m
Correction for elevation = 0.07 *450/ = 1.105
Corrected runway length = 1800 * = 1989 m
Standard temperature at the airport site = *450/1000 = 12.08C
Airport reference temperature = 18 + (27-18)/3 = 21C
Rise in temperature = 21 – = 8.92C
Correction for temperature = 0.01 * =
Corrected length for temperature = 1989 * = 2166 m
Correction for gradient = 0.01 * = 1.05
Final runway length = 2166 * 1.05 = 2275 m

52. …??