The ATSB will monitor the introduction of new take-off procedures at Sydney Airport after a British Airways 787 and Qantas A330 flew too close to each other in September last year.
The incident saw the Boeing aircraft’s collision avoidance system become activated before its first officer spotted the Airbus.
A report into the ‘loss of separation occurrence’ revealed how an unusual set of circumstances led to the mix-up, including that the traditionally longer-haul A330-200 was operating a domestic flight meaning it had a higher climb performance.
The ATSB’s director of transport safety, Stuart Macleod, said, “Maintaining separation in high traffic terminal areas, such as Sydney, requires that both controllers and flight crews remain vigilant, maintain open communications, and use the available systems and tools to minimise the risk of errors.
“When sequencing departures, controllers should consider a number of factors, including how the flight duration (and the associated fuel load) will likely affect aircraft climb performance.”
The full report reveals how, on the afternoon of 28 September 2022, a Boeing 787-9, operated by British Airways, took off from Sydney’s runway 16R for a scheduled passenger service to Singapore.
Approximately three minutes later, an Airbus A330-200, operated by Qantas, departed the same runway for a scheduled passenger service to Cairns.
Both aircraft were directed to follow the same standard instrument departure (SID) routing, the DEENA 7 SID, for their respective climbs to 28,000 ft.
This SID required the aircraft to meet two separate conditions after take-off before turning to the north-west: they had to pass the DEENA waypoint, and they had to climb to at least 6,000 ft.
“Because aircraft have to satisfy two separate conditions prior to turning, there is no way to ensure aircraft will turn at the same location when conducting the DEENA 7 SID,” Macleod said.
In the September incident, the trailing A330 was being used on a domestic flight, with a correspondingly lower fuel load and higher climb performance than it would have had for an international flight.
“The departure controller did not expect this and instead expected the A330 to have a similar climb performance to the 787 it was following, thus remain behind it and turn at about the same location.”
Instead, the A330 reached 6,000 ft as it passed DEENA and began its turn about 20 km from the airport. Meanwhile, the heavier 787 reached 6,000 ft sometime after passing DEENA and began its own turn about 25 km from the airport.
This meant the trailing A330 was turning inside the path of the 787, as they both climbed to the same flight level.
During the event, the separation between the aircraft was reduced to 2.4 NM laterally and 600 ft vertically – below the required separation standards of either 4 NM laterally (for ‘heavy’ aircraft) or 1,000 ft vertically – before the controller advised the aircraft and separation was re-established.
The British Airways flight crew later advised they had received a traffic collision avoidance system (TCAS) traffic advisory during the event, and the first officer had subsequently visually identified the A330.
The ATSB final report notes that, in the last decade in Australia, there has been eight loss of separation occurrences involving aircraft cleared on a SID, where a following aircraft has climbed faster than the preceding aircraft.
Of these, six were at Sydney, and five involved the DEENA 7 SID.
“Airservices Australia has advised the DEENA 7 SID has been redesigned to remove the two conditional requirements of the procedure,” Macleod said.
“The changes are planned to be part of the first implementation package for Western Sydney International Airport, but as the timeframe for this implementation is unknown, the ATSB will continue to actively monitor this open safety issue.”
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- Source: https://australianaviation.com.au/2023/03/british-airways-787-and-qantas-a330-fly-too-close/
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