Two Qantas jets flew within 150m of each other in what the Australian Transport Safety Bureau (ATSB) is calling a “serious incident”.
It took place while a trainee Air Traffic Control (ATC) worker was on duty under the supervision of an on-the-job training instructor, according to a new ATSB report.
As there wouldn’t be enough runway spacing between the two planes, the trainee controller instructed the 737 flight to perform a ‘go-around’ (circling in the air instead of landing).
However, this led to a “loss of separation between their aircraft and the departing A330”, according to the ATSB.
The distance between the two planes was at one point just 150m vertically and 800m laterally. This falls far short of the minimum that separation controllers are required to maintain between aircraft operating inside terminal area airspace: 5km laterally or 300m vertically.
Attempting to increase the distance between the two aircraft, the controller instructed the 737 to turn further right. The 737 was flying at about 300 vertical metres, below the minimum altitude at which planes are allowed to turn at night.
The jets flew close enough to each other that a traffic advisory alert was triggered from the A330’s airborne collision avoidance system (ACAS).
The A330 first officer saw the 737’s proximity and reduced the aircraft’s angle of bank in response.
The flight’s captain radioed ATC to say that it was “very close”, and the controller told the A330 to turn left.
Following the loss of separation, the A330 climbed to 1,525m and flew to Melbourne without incident, while the 737 made a second approach to the runway and landed safely.
An investigation into events is ongoing, but the ATSB has classed it as a “serious incident” in a preliminary report.
Qantas has emphasised that the two aircraft were never in danger of colliding, even had they stayed on the same flight paths.
“Our crew followed directions from air traffic control at all times,” a spokesperson told The Independent. “We’re continuing to work with the ATSB on their ongoing investigation.”