ATSB releases report on microburst windshear serious incident
The Australian Transport Safety Bureau (ATSB) today released a report on the circumstances of a serious incident where a fare-paying scheduled passenger flight encountered microburst windshear near Brisbane last year.
Windshear is a change in wind speed and/or direction, including updrafts and downdrafts. An aircraft may experience a significant deterioration in flight performance when exposed to windshear of sufficient intensity or duration.
On 18 January 2001, a Boeing 737-476 aircraft (VH-TJX) encountered microburst windshear at 7.29am while conducting a go-around from runway 19 at Brisbane aerodrome.
The aircraft was operating a scheduled fare-paying passenger service from Sydney to Brisbane when it encountered an intense thunderstorm.
The report states:
- As the aircraft passed 1,000 feet during the landing approach, it encountered rain and some isolated hail. The approach lights for runway 19 were visible to the crew, and the pilot in command elected to continue the approach.
- At about 500 feet, the weather deteriorated rapidly, and the aircraft encountered hail and turbulence.
- At a height of 171 feet above ground level, the pilot in command discontinued the approach and applied go-around engine thrust.
- The aircraft commenced to climb normally at about 3,600 feet/minute, however, shortly after the go-around was initiated, the climb performance substantially reduced to less than 300 feet/minute due to the effects of the microburst downdraft and from flight through heavy rain.
- The pilot in command applied maximum engine thrust to improve the aircrafts heavy climb performance, and advised the Aerodrome Controller that the aircraft had encountered severe windshear.
- The crew then diverted the aircraft to Maroochydore where it landed without further incident.
The occurrence highlights that thunderstorms and convective activity in terminal areas are a significant issue in Australian and international aviation.
This incident also highlights that without extensive Doppler weather radar capabilities, and in the absence of appropriate systems designed to detect hazardous windshear in Australia there is a need for collaborative decision making among forecasters, controllers, pilots and operators during periods of intense or severe convective weather.
In its report, the ATSB made a number of recommendations to Airservices Australia, the Bureau of Meteorology and the Civil Aviation Safety Authority (CASA). It also notes that a number of safety actions have been initiated or implemented by the operator, Airservices and CASA as a result of the investigation.
The safety actions include:
- CASA is developing regulatory requirements and standards for organisations providing meteorological services in support of air navigation and air traffic services within Australia and its territories.
- Airservices Australia will develop a refresher training module based on the circumstances of this occurrence and will mandate its completion for all Full Performance Controllers.
The operator has initiated or implemented a number of safety actions as a result of the ATSB investigation, including:
- The development of a weather radar training package for flight crews and enhancement of flight crew education on the performance deterioration of aircraft in heavy rain.
- Undertaking a project to integrate qualified meteorologists into its dispatch processes in order to initiate best practice improvements.