A packed Cathay Pacific jet put on a crash course with another passenger plane by air traffic control blunders was less than two minutes from a collision when the pilots swerved to avoid each other, an investigation has found.
The pilot of a Cathay Airbus A330 carrying 309 passengers from Hong Kong to Melbourne was 55 kilometres - or 120 seconds - from an oncoming Virgin Blue Boeing 737 over northern Australia on December 22, 2009, when the Airbus' onboard collision alarm system sounded.
A report into the incident by the Australian Transport Safety Bureau released yesterday revealed that a string of errors by an 'inadequately equipped' air traffic controller brought the planes dangerously close.
When the Cathay Pacific captain contacted the controller about the TCAS (traffic alert and collision avoidance system) alarm, the controller instructed him to climb, a manoeuvre that began when the two planes were just 46 kilometres apart, the report said.
Seconds later, with just 37 kilometres separating them and the TCAS alarm indicating they were still heading towards each other, both pilots swerved to their right without waiting for air traffic control (ATC) clearance.
The report said: 'The flight crews of both aircraft reported that they considered the situation significant enough to commence diversions right of track without obtaining an ATC clearance prior to their respective manoeuvres.'
Aviation rules state that pilots can take such action without ATC clearance only in an emergency. The two aircraft were around 19 kilometres apart at the time, the report noted.
The Virgin Blue plane, carrying 120 passengers from Melbourne to Darwin, had been flying at a pre-approved, non-standard level because of turbulence when it found itself on a head-on course with the Cathay Pacific plane, which was on an 11 1/2-hour flight from Hong Kong.
The controller told investigators he had meant to ask the Virgin Blue plane to descend as both planes entered his sector but 'forgot to implement that plan'.
He was preoccupied with an unrelated discussion with another ATC sector controller throughout the incident and failed to issue a required safety alert when the Cathay Pacific pilot first alerted him to the situation. The actions of the controller 'indicated a reduced awareness of the criticality of the situation'.
The controller had joined government air traffic control body Airservices Australia 14 months earlier and had ATC experience with the Royal Australian Air Force, allowing him to take a shortened 11-week training course. 'The incident demonstrated a less-than-effective recovery action by the controller in response to the lack of separation assurance,' the report said. He was 'inadequately equipped to manage the imminent conflict'.
Crediting both cockpit crews for their responses, the report said: 'The flight crews of both aircraft identified the traffic confliction and initiated avoidance action to maintain separation. The actions of both flight crews were significant in alerting the controller to the conflict and ensuring the safety of the aircraft through the subsequent controller-initiated level change and flight crew-initiated diversions right of track.'
The report said Airservices Australia had conducted its own internal investigation and had recommended action to address safety factors arising from the incident, which the Transport Safety Bureau said it would be satisfied with once implemented.
Reacting to the report, Henry Craig, Cathay Pacific's general flying manager, said: 'Both aircrafts' TCAS equipment generated appropriate and early alerts which led the Cathay Pacific A330's flight crew to query the level and proximity of the Boeing 737, before initiating track diversions to avoid the other aircraft. This was the appropriate action to take.'
The number of air accidents involving deaths in 2010, up from 23 in 2009