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.