1. Lecture 8: Approach & Landing Performance
AIRCRAFT WEIGHT & PERFORMANCE

2. IANS / ATC Training / Courses / Basic / ACFT
Factors CRUISE
Introduction
Climb
Cruise / En-route
Descend
Approach & Landing
Take-off
Vicinity=area nearby
When an aircraft is in vicinity of the destination airport, it is considered to be in the final approach phase of its flight.
Edition 1.1

3. Final Approach
During the final approach, from approximately 10nm range, the flaps are progressively lowered.
In addition, the landing gear is also lowered at about 5nm from touchdown. Both flaps and landing gear produce drag and will require the addition of power.
The spoilers are "armed", i.e. they are put in a state whereby they will be automatically deployed fully on touchdown.

4. Landing
Following the final approach the aircraft will start the landing phase.
Landing begins from certain height (35ft/50ft) above the runway until a complete stop by the aircraft.
It comprises of an airborne segment, touchdown and a ground roll (the point from touchdown to reaching a full stop).
Once on the ground the thrust reverser and spoilers will be fully deployed and wheel breaking will be applied in order to stop the aircraft more efficiently and use less landing distance.
Thrust reverser=to provide thrust in the opposite direction

5. Landing Performance
 In many cases, the landing distance of an airplane will define the aircraft landing performance.
Before commencing an approach, the crew shall check and confirm that the landing distance required is less than the landing distance available.

6. LDR & LDA
The landing distance required (LDR) shall be the horizontal distance required to land and come to a complete stop from a point on the approach flight path at a selected height above the landing surface. (ICAO Annex 8 Part IV Paragraph )
The landing distance available (LDA) is the length of the runway which is declared available by the appropriate Authority and suitable for the ground run of an aeroplane landing. (JAR-OPS 1.480(a)(2)(i) (5)).

7. LANDING DISTANCE
The minimum landing distance is obtained by landing at some minimum safe speed which provides enough control.
To obtain minimum landing distance at the specified landing speed, the forces which act on the airplane must provide maximum deceleration during the landing roll. (that is, extensive use of the brakes).
Thus, any factors that reduces the efficiency of the brakes will increase landing distance. Any item which alters the landing speed or deceleration rate during the landing roll will affect the landing distance.
Since the objective during the landing roll is to decelerate, the thrust should be the smallest possible.

8. Two types Landing Accidents
Land an aircraft on a runway where the landing distance available is shorter than the landing distance required will lead to accidents (overrun on landing).
Overrun on Landing:
A landing aircraft is unable to stop before the end of the runway is reached.
Undershoot on Landing:
An aircraft attempting a landing touches down in the undershoot area of the designated landing runway.

9. Overrun on Landing:
On 2nd August 2005, and Air France A340, comes in too high for landing at Toronto Airport during thunderstorm. The runway is short and the pilots deploy the thrust reversers too late. The A340 overruns the runway. Although the aircraft is burnt out, all 309 people onboard survive by evacuating the aircraft in less than 90 seconds.
B738, Kingston Jamaica, 2009: On 22 December 2009 a Boeing , operated by American Airlines, ran off the eastern end of runway 12 on landing at Norman Manley International Airport, Kingston, Jamaica, having landed on the wet runway with a tailwind.
Runway overrun in storm, short runway, pilot error
Air France Flight 358 comes in too high for landing at Toronto Pearson International Airport during a storm. The runway is short and the pilots deploy the thrust reversers too late. The A340 overruns the runway and smashes through the airport fence before plunging into a small ravine. Although the aircraft is burnt out, all 309 people onboard survive by evacuating the aircraft in less than 90 seconds.

10. Overrun on Landing:
E170, Cleveland OH USA, 2007: On 18 February 2007, while landing at Cleveland Hopkins International Airport, USA, an Embraer ERJ170 overran the snow-contaminated runway.
DC10, Tahiti Hawaii, 2000 : On 24th December 2000, a Hawaiian Airlines DC-10 overran the runway at Tahiti after landing long on a wet runway having encountered crosswinds and turbulence on approach in Thunderstorms.
MD82, Little Rock USA, 1999 : On 1 June 1999, an MD-82 belonging to American Airlines, overran the end of the runway during landing in thunderstorm. The captain and 10 passengers were killed.

11. Undershoot on Landing:
F70, vicinity Munich Germany, 2004 : On 5 January 2004, a Fokker 70, operated by Austrian Airlines, carried out a forced landing in a field 2.5 nm short of Munich Runway 26L following loss of thrust from both engines due to icing.
JS31, Fort St. John BC Canada, 2007 :
On 9 January 2007, Jetstream 31 from Grand Prairie, Alberta made an to Runway 29 at Fort St. John, British Columbia and touched down 320 feet short of the runway striking approach and runway threshold lights. The right main and nose landing gear collapsed and the aircraft came to rest on the right side of the runway, 380 feet from the threshold. There were no injuries to the 2 pilots and 10 passengers. At the time of the occurrence, runway visual range was fluctuating between 1800 and 2800 feet in snow and blowing snow, with winds gusting to 40 kts.

12. Factors affecting Landing Performance
Put simply, the LDR must be less than the LDA.
Aircraft performance (LDR and landing speed) is calculated by consider several factors
Aircraft performance during landing depends on a number of factors, principally:
Runway Condition
Landing Speed
Wind
The aircraft landing speed & mass;
The surface wind and temperature;
The runway elevation and slope;
The runway surface conditions (dry, wet or contaminated); and,
The condition of aircraft braking systems.
Air Density
Aircraft Configuration
Aircraft Mass

13. Factors affecting Landing Performance
Landing speed: The distance required for landing is proportional to the square of the aircraft’s ground speed on landing. Thus increased landing speed will give a significantly increased landing distance requirement.

14. Factors affecting Landing Performance
Aircraft landing mass: Beside the landing speed, aircraft mass affects the deceleration and the required brake drag as well.
Increased mass reduces the deceleration for a given deceleration force and therefore increases the landing distance (inertia).
In the same time, increased mass increases the brake drag available (greater pressure on the ground) and this decreases the landing distance.
However, the major effect is that the landing distance required will increase with increasing mass.
The effect of gross weight on landing distance is one of the principal items determining the landing distance of an airplane.
One effect of an increased gross weight is that the airplane will require a greater speed to support the airplane at the landing angle of attack and lift coefficient.
When minimum landing distances are considered, braking friction forces predominate during the landing roll and, for the majority of airplane configuration, braking friction is the main source of deceleration.

15. Factors affecting Landing Performance
Wind: The effect of wind on landing distance is large and deserves proper consideration when predicting landing distance.
The wind affects the deceleration force during the landing roll.
A headwind component adds to the deceleration force and therefore increases the braking efficiency & reduce the landing distance.
While a tailwind component for the same reason reduces the braking efficiency & increase the landing distance.
**Strong cross-winds, turbulence and wind shear make handling difficult and are likely to result in an increased landing distance.
The effect of wind on deceleration during the landing is identical to the effect on acceleration during the takeoff.
A headwind which is 10 percent of the landing airspeed will reduce the landing distance approximately 19 percent but a tailwind which is 10 percent of the landing speed will increase the landing distance approximately 21 percent. Figure illustrates this general effect.

16. Factors affecting Landing Performance
Air density: Low density (high temperature, low pressure or high aerodrome elevation) will give an increase in the required landing distance due to the decrease of the engine reverse thrust and higher landing speed.
Higher air density, shorter landing distance
The effect of pressure altitude and ambient temperature is to define density altitude and its effect on landing performance.
An increase in density altitude will increase the landing speed but will not alter the net retarding force.
Thus, the airplane at altitude will land at the same indicated airspeed - as at sea level but, because of the reduced density, the true airspeed (TAS) will be greater.
Since the airplane lands at altitude with the same weight and dynamic pressure, the drag and braking friction throughout the landing roll have the same values as at sea level.
As long as the condition is within the capability of the brakes, the net retarding force is unchanged and the deceleration is the same as with the landing at sea level. Since an increase in altitude does not alter deceleration, the effect of density altitude on landing distance would actually be due to the greater TAS (true airspeed).

17. Factors affecting Landing Performance
Runway conditions: Landing performance depends on the runway braking conditions. A hard dry surface gives the good braking condition & reduce landing distance.
If the runway is wet or contaminated the landing distance achieved will be increased.
The presence of standing water, snow or ice on the runway has a particularly serious effect on landing performance and if it cannot be cleared, it must be reported as accurately as possible. Special techniques must be used by pilots when landing on contaminated runways. Ice or snow on the runway or runways on which hydroplaning occurs will give a very small coefficient of friction.
If the runway is sloping, the weight component along the runway will add to or subtract from the deceleration force. A downhill slope will increase the landing distance required and an uphill slope will reduce the landing distance.
Runway Conditions.
The maximum landing mass and the landing speed depend on the runway braking conditions. If these have been inaccurately reported or if the runway is wet or contaminated when its condition was reported as being dry, the landing distance achieved will be increased.
The presence of standing water, snow, slush or ice on the runway has a particularly serious effect on landing performance and if it cannot be cleared, it must be reported as accurately as possible. Special techniques must be used by pilots when landing on contaminated runways.
Weather Conditions.
The maximum landing mass and landing speed is calculated based on the reported wind and temperature. Significant changes to the reported conditions will affect the landing distance achieved.

18. Factors affecting Landing Performance
Aircraft Configuration:
Failure of the devices which affect the aircraft braking (flaps, brakes, landing gear, reverse thrust) can have a serious effect on landing performance.
These devices must functioning well to stop the aircraft more efficiently and use less landing distance.
↑ Flaps = ↓ Distance
↑ Friction = ↓ Ground Roll

19. Summary
The most critical conditions of landing performance are the result of some combination of high gross weight, high density altitude, and unfavorable wind.
These conditions produce the greatest landing distance and provide critical levels of energy dissipation required of the brakes.
In all cases, it is necessary to make an accurate prediction of minimum landing distance to compare with the available runway.
A polished, professional landing technique is necessary because the landing phase of flight accounts for more pilot caused airplane accidents than any other single phase of flight.
Headwind, Shorter landing distance

20. Hydroplaning
Hydroplaning or aquaplaning by the tires of vehicle (aircraft) occurs when a layer of water builds between the rubber tires of the vehicle and the road surface, leading to the loss control.
Hydroplaning of aircraft tires is often a contributing factor in take-off and landing overrun accidents.
When a tire rolls along a wet surface, it is squeezing water from under the footprint. This
squeezing process generates water pressures on the surface of the tire footprint. At a critical
speed the tire will be completely separated from the ground surface by a film of water. This
speed is called the hydroplaning speed. The water pressure build-up under the tire originates
from the effects of fluid density and fluid viscosity. Two types of hydroplaning can be
distinguished:
• Dynamic hydroplaning
• Viscous hydroplaning

21. Hydroplaning
The ability to brake can be completely lost when the tires are hydroplaning because a layer of water separates the tires from the runway surface.
Not only reduce braking effectiveness, hydroplaning also cause aircraft lost directional control.
There are three types hydroplaning which are:
Dynamic Hydroplaning
Viscous Hydroplaning
Reverted Rubber Hydroplaning
In general both types of hydroplaning can occur at the same time. This paper will focus on
dynamic hydroplaning because this is the most important one.
Dynamic hydroplaning is the result of the hydrodynamic forces developed when a tire rolls on a
water covered surface. This is a direct consequence of the tire impact with the water that
overcomes the fluid inertia. The magnitude of the hydrodynamic force varies with the square of
the tire forward ground speed and with the density of the fluid. Dynamic hydroplaning is
influenced by tire tread, water layer thickness and runway macrotexture. Macrotexture is the
runway roughness formed by the large stones and grooves in the surface of the runway. When
there is sufficient macro texture on the surface and / or the tire has proper tread, total dynamic
hydroplaning will usually not occur. However, hydroplaning can occur when the water depth is
high enough so that both tire tread and runway macro texture cannot drain the water quick
enough.

22. Types of Hydroplaning 1. Dynamic Hydroplaning:
Occurs when there is water on the runway. Water is not displaced fast enough to allow the tire to contact the surface, and the tire rides on a wedge of water.
Viscous Hydroplaning:
On smooth or contaminated surfaces (oil, rubber, dust, de-ice fluid, fuel) a thin film of water resists penetration by the tire and reduces braking action. Can occur at lower speeds.
Reverted Rubber Hydroplaning:
As a tire skids and rubber melts it acts as a seal which traps water under the tire footprint where it is heated to steam which supports the tire off the runway surface.
Dynamic hydroplaning is a condition where the tire is lifted completely above the surface of the runway. As little as one-tenth inch of water combined with the “NASA critical speed” of the tire is the causal factor.
Viscous hydroplaning can occur at slower speeds and rather than the water lifting the tire from the pavement, the tire slips on a thin film. This occurs on smooth runways.
Reverted Rubber (Steam) Hydroplaning: Encountering an emergency during takeoff or landing often causes the pilot to “lock” the brakes. If this occurs on a wet runway, the tire track area heats up due to friction causing some of the rubber to “revert back” to a gummy state, trapping water. The water turns to steam and steam pressure lifts the tire from the runway.

23. Non-Rotating Tire =7.7×√PSI