|
Section 21 (2) of the Transport Safety Investigation Act 2003 (TSI Act) empowers the ATSB to discontinue an investigation into a transport safety matter at any time. Section 21 (3) of the TSI Act requires the ATSB to publish a statement setting out the reasons for discontinuing an investigation. The statement is published as a report in accordance with section 25 of the TSI Act, capturing information from the investigation up to the time of discontinuation. |
Overview of the investigation
The ATSB commenced an investigation into an unforecast weather event involving a Qantas Boeing 737-838 aircraft, registered VH-VYZ, which occurred at Adelaide Airport, South Australia on the morning of 16 August 2020.
The weather forecast used for pre-flight planning did not require the carriage of fuel for an alternate destination, however, the flight crew requested additional fuel for other operational reasons. Once airborne, an updated forecast identified fog at Adelaide that was expected to clear prior to the aircraft’s estimated time of arrival. The flight crew prepared for possible diversions in the event that the weather did not clear at the expected time.
During the flight, there was an unexpected outage of Bureau of Meteorology (BoM) services at Adelaide, which resulted in an updated forecast not being available prior to the crew’s calculated latest divert time. However, the weather forecast received earlier in the flight was still valid for the expected time of landing.
After the latest time to divert had passed, the crew received an updated forecast indicating that the fog would clear later than originally expected. Despite the extended fog duration, there was still sufficient fuel on board for the aircraft to operate safely for more than 30 minutes beyond the new clearing time.
During the approach phase, the flight crew interrogated the automatic terminal information service[1] multiple times noting that the observed conditions were improving. They also received verbal advice from air traffic control that the conditions were improving.
At 0914 Central Standard Time,[2] the flight crew conducted a missed approach due to lack of visual references and commenced holding in the vicinity of the airport. About 30 minutes later, just before 0945 the flight crew made another approach deciding to use the aircraft’s autoland[3] system in order to minimise their workload. Weather camera images provided by the Bureau of Meteorology showed that the weather during the second approach had improved since the time of the missed approach.
The captain reported being visual at the minima and the aircraft landed safely, well above minimum fuel reserves.
As part of the investigation the ATSB:
- interviewed the flight crew,
- collected and examined the weather data including forecasts, weather and camera images,
- examined the recorded flight and air traffic data,
- examined the operator’s flight planning procedures and in-flight decision making in relation to weather.
The ATSB found that at all stages of the flight the operator and flight crew acted in accordance with the regulations and in alignment with operational guidance.
In 2013, the ATSB published a safety research report into the effects of Australian aviation weather forecasts on aircraft operations at Adelaide and Mildura Airports (AR-2013-200). The results of the report encouraged the retrieval of weather forecasts at the latest possible time prior to arrival. In this case, that weather was not available due to the outage and that aspect is being investigated by the BoM.
Reasons for the discontinuation
Based on a review of the available evidence, the ATSB considered it was unlikely that further investigation would identify any systemic safety issues or important safety lessons. Consequently, the ATSB has discontinued this investigation.
The evidence collected during this investigation remains available to be used in future investigations or safety studies. The ATSB will also monitor for any similar occurrences that may indicate a need to undertake a further safety investigation.
__________
- Automatic terminal information service (ATIS) is a continuous broadcast of recorded aeronautical information at airports containing information including current weather.
- Central Standard Time (CST): Coordinated Universal Time (UTC) + 9.5 hours
- The autoland system automates the landing procedure of the aircraft’s flight, supervised by the flight crew.