Landing performance

The performance data for landing an aircraft can be obtained from the aircraft's flight manual or pilot's operating handbook. It will state the distance required to bring the aircraft to a stop under ideal conditions, assuming the aircraft crosses the runway threshold at a height of 50 ft, at the correct speed. The actual landing performance of an aircraft is affected by many variables which must be taken into account. The performance data for landing an aircraft can be obtained from the aircraft's flight manual or pilot's operating handbook. It will state the distance required to bring the aircraft to a stop under ideal conditions, assuming the aircraft crosses the runway threshold at a height of 50 ft, at the correct speed. The actual landing performance of an aircraft is affected by many variables which must be taken into account. The weight of an aircraft is one of the basic factors that determines the length of the landing roll of an aircraft. An increase in weight increases the stall speed of an aircraft. Stall is a reduction in the lift coefficient generated by a wing as angle of attack increases. Therefore, the minimum approach speed is much higher in case of heavier aircraft. The kinetic energy (1/2 mV2) that has to be overcome to stop an airplane, is a function of the mass of the airplane and the square of the speed at touchdown. The kinetic energy in case of heavier aircraft is higher and the brakes have to absorb this greater energy, increasing the landing run of an aircraft. A decrease in density of air results in decrease in both aircraft and Engine performance. High elevation airports are characterized by low pressure and high ambient temperatures. The True Airspeed (TAS) will be higher than the Indicated airspeed indicated by the Airspeed indicator to the pilot in air of low density. This increase in TAS leads to greater touchdown speed hence increases the landing roll. More energy has to be absorbed by the brakes thus demanding the need of a longer runway. An increased density altitude means a longer landing distance. The headwind reduces the landing distance for an aircraft. Landing into a headwind reduces the Ground Speed (GS) for the same TAS. This is beneficial to pilots as well as Air traffic controllers (ATC). An aircraft landing into a headwind will require less runway and will be able to vacate the runway sooner. If the headwind decreases near the ground, there's a decrease in the performance of the aircraft and it will tend to sink and possibly under shoot the aiming point.Tailwind increases the Ground Speed of an aircraft for the same TAS and thus a longer runway distance will be required for an aircraft to land. Landing in a tailwind situation could lead to the aircraft over shooting the runway and colliding with objects or terrain. Runway conditions affect take off and landing performance of an aircraft. The runway may be made up of concrete, asphalt, gravel or grass. An important safety concern at airports is the contamination of the runways due to ice, snow, water, rubber deposits etc. The landing distance required by an aircraft is much more in case of low friction runways which do not facilitate effective braking to occur. Aquaplaning is a phenomenon in which directional control is lost because of the presence of film of water between the rubber tires and the runway surface. The construction of grooved surface runways and regular maintenance, especially rubber removal, both help reduce runway slipperiness and facilitate good ground handling and effective braking.