High winds caused problems for pilots trying to land at Leeds Bradford Airport yesterday.
'Wind shear' - a meterological phenomenon which involves a change in wind speed or direction over a short distance - led to several aborted landings on Sunday.
A KLM jet arriving at Leeds Bradford from Amsterdam took four attempts to land on Sunday night. Local photographer Andrew Easby filmed aircraft coming in to land.
Wind shear has been a factor in several air crashes in the past and since 1993 it has been compulsory for commercial aircraft to be fitted with wind shear detection equipment.
The outflow from a storm causes changes in the wind velocity just above ground level, leading to a headwind that increases airspeed. Pilots often react by reducing engine power if they are unaware of the wind shear. As the aircraft descends, the headwind lessens, which reduces the airspeed of the plane. On the other side of the downdraft, the headwind becomes a tailwind, which reduces the lift generated by the wings. The aircraft can then be left in a slow descent with insufficient power. Accidents have been caused by the plane being too low to then recover before grounding.
Between 1964 and 1985, there were 26 major air crashes caused by wind shear in the USA alone, with 620 passengers killed. In 1985, a Delta Airlines plane flying from Florida to Los Angeles crashed while landing in Dallas, killing 137, after encountering a microburst caused by a storm. The number of accidents has dramatically reduced since wind shear detection technology became mandatory.
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