PAUL PHELAN / CAIRNS
Heavy precipitation can reduce aerodynamic efficiency, according to a report into an incident involving a Qantas Boeing 737-400 that experienced a severe downburst on approach in January 2001.
The report, by Australia's Air Transport Safety Bureau (ATSB), reveals that heavy rain or hail can destroy lift and trigger erroneous warnings from radio altimeters and ground proximity warning systems.
The aircraft was on approach at Brisbane Airport when a severe downburst almost threw the aircraft at the ground. The crew had initiated a go-around when it encountered severe windshear, hail and turbulence, but despite an attempt to climb on full power, descent continued to a radio altitude of 171ft (52m) before the aircraft recovered into a 3,600ft/min (18.3m/s) climb.
The report urges improvements to controller and pilot windshear training, and improved real-time aerodrome windshear indicators to warn crews of danger. The ATSB says that had the controllers been provided with aerodrome warnings and lightning alerts, they would have issued a thunderstorm hazard alert to approaching aircraft.
Source: Flight International
