- 1 Introduction
- 2 Landing flare
- 3 Required landing distance
- 4 Deceleration on the Runway
- 5 Short landing operations
- 6 Defences against threats
- 7 See also
- 8 Reference
- 9 Author
- the flare
- the landing roll
A detailed landing phase of a fixed wing aircraft can be presented with the following sequence
- Final approach before the runway threshold
- Flare after the runway threshold
- Touchdown and de-rotation
- Roll out and deceleration
Position A: Aircraft is on final. Position B: Aircraft power thrust is on idle and pilot will increase slightly aircraft pitch. Position C: It is the flare phase of the flight.
If executed correctly, the flare will result in the aircraft achieving the appropriate landing attitude by:
- A power setting at or near idle,
- A reduced rate of descent
- A decaying airspeed
Appropriate deceleration procedures should be initiated immediately following the touchdown as dictated by the calculated stopping distance and the available runway.
Required landing distance
The determination of landing distance required for aircraft to land is calculated by taking into account the effect of various influencing factors, including runway construction, surface conditions and the use of aircraft devices which are available to assist deceleration.
Required landing distance = calculated landing distance + safety factor.Safety factors will vary according to the aircraft type, the runway conditions (dry, wet or contaminated), and the runway construction and parameters (slope, altitude).
Deceleration on the Runway
- Reverse engine power
- Mechanical spoilers.
Engine power and reverse thrust/propeller
Braking effectiveness is affected by:
- The degree of brake wear created by wheel rotation When brake temperature indication is available on the flight deck, it must be within prescribed limits before a take-off roll is commenced so that effective braking is available if a take-off is rejected. System faults or inappropriate use of brakes during a long taxi out can raise brake temperatures into cautionary ranges where a delay for take-off may be required.
- The tyre parameters (inflation pressure, condition)
- The condition of the runway surface
In small aircraft, the brake system can be a master cylinder and it does not need hydraulic pumps. In larger aircraft, the brake system can be powered by hydraulic fluid using pump or in last designed aircraft by electric systems.
Historically, the pilots use a single lever to apply all brakes symmetrically and the brake control was mechanical. Now, the pilots have the toe operated brake controls incorporated into the rudder pedals. The foot operated controls by the pilot through applying left or right brakes independently (differential braking) can maintain directional control during take-off or landing roll when the airspeed is too low for the aerodynamic controls to be effective.
The mechanical spoilers are activated with a mechanical deflection of parts of the wing upper surfaces. These spoilers can assist deceleration in two ways:
- By increasing aerodynamic drag
- By increasing the effective downward load on the landing gear and thereby increasing the efficiency of wheel braking.
Runway Surface Conditions
The effectiveness of decelerating on the runway after a landing or a rejected take-off decision will be affected by the surface friction. The surface can be contaminated by water, ice, snow, oil … etc …
When the surface is contaminated, the landing distance or rejected take-off roll distance is increased. Regulation has made some recommendation with considering a safety factor different in function of the type of contamination. Consult the document about landing distance calculation in order to have these values.
Short landing operations
Some aircraft operations need a short landing operation due to the remoteness of the airport or to physical limitations relating to extending the runway.
The short landing operations will only be approved with considering the following criteria:
- The vertical distance between the path of the pilot’s eye and the path of the lowest part of the wheels, with the aircraft established on the normal glide path, shall not exceed 3 m.
- The visibility/RVR must not be less than 1,5 km.
- Minimum pilot experience, training requirements and special aerodrome familiarisation must be specified
- The charts and country’s regulation may impose additional conditions necessary for a safe operation (aircraft characteristics, orographic characteristics in the approach area, and missed approach landing considerations).
Defences against threats
On a typical flight with a duration of 1.5 hours, the landing phase accounts for approximately 1% of the total time. However, according to the Boeing Aircraft Aviation Safety department, landing accidents, in jet powered aircraft have resulted in approximately 20% of aviation fatalities.
The defences for landing operation are:
- Stabilised approach implies that the flight path would terminate within the touchdown zone. If the approach is not stable, a missed approach should be executed.
- Flare height should be at the height recommended in the aircraft flight manual. Adjustments for crosswind or wind gust conditions may be required.
- Pitch from approach attitude to landing attitude should be accomplished at a rate which prevents ballooning but ensures landing attitude is achieved prior to touchdown. Excessive pitch should be avoided.
- Power/thrust reduction should comply with the recommended values in the aircraft flight manual. Adjustments for crosswind or wind gust conditions may be required.
- Touchdown should be appropriate for the aircraft type and should avoid excessive float.
- Deceleration procedures during roll out should be initiated immediately following main wheel touchdown.
- VID 150259 - Creation
- VID 256272 - Wiki Integration
DATE OF SUBMISSION
- 02:19, 14 May 2021
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