CROSS-WIND APPROACH AND LANDING SYSTEM OF AN AIRCRAFT

In aviation, a crosswind landing is a landing maneuver in which a significant component of the prevailing wind is perpendicular to the runway center line.

Aircraft in flight are subject to the direction of the winds in which the aircraft is operating. For example, an aircraft in flight that is pointed directly north along its longitudinal axis will, generally, fly in that northerly direction. However, if there is a west wind, the actual track of the aircraft will be slightly to the east of north. If the aircraft was landing north on a north-south runway, it would need to compensate for this easterly drift caused by the west crosswind.

In situations where a crosswind is present, the aircraft will drift laterally as it approaches the runway. This drift poses significant safety issues because safe operation of the undercarriage requires the body and track of the aircraft to be aligned with the runway at touch down. The landing gear designs of the “pioneer era” 1909 Bleriot XI, and the much later Cold War B-52 strategic jet heavy bomber, were designed and each built with an unusual feature to counteract the problem:

with the B-52, all four of its landing gear bogies could be steered, allowing the aircraft to land with the wheels facing the direction of travel even if the nose was not pointed in the same direction. The Bleriot XI had pivoting main gear legs, which passively allowed the main gear wheels to castor together about each of their vertical axes as a unit to allow small-angle crosswind landings, with bungee-cord loaded rigging members between the lower ends of the main wheel forks, to bring the wheels back to a “directly-ahead” orientation after touchdown. If the crosswind landing is not executed safely, the aircraft may experience wingstrike, where a wing hits the runway.

Techniques

The following guidelines are advised by Boeing for a crosswind landing. These guidelines assume steady wind (no gusting). These winds are measured at 10 m (33 feet) tower height for a runway 45 m (148 feet) in width. Basically, there are 3 landing techniques which may be used to correct for cross winds: de-crab, crab, and sideslip.

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