The Australian Transport Safety Bureau (ATSB) is investigating a separation incident between aircraft operated by Hong Kong's Cathay Pacific and Australia's Virgin Blue over Australia's Northern Territories on 22 December.

At 0252 CST (Central Standard Time), a southbound Cathay Airbus A330-300 aircraft on the Hong Kong-Melbourne route and a northbound Virgin Blue Boeing 737-800 aircraft on the Melbourne-Darwin route were on "the reciprocal track also at non-standard FL370", says the ATSB.

The ASTB has classified the incident as serious.

"When the crew of the A330 questioned the controller, the controller instructed the A330 crew to climb to FL380 and cleared the aircraft to divert to right of track," says ATSB. "The crew of the 737 then advised the controller they were diverting 10NM right of track. There was a breakdown of separation standards. The investigation is continuing."

Cathay Pacific confirms that the incident took place and the "appropriate avoidance action was taken by the Cathay Pacific crew." It has filed a report with the Hong Kong Civil Aviation Department.

An investigation report has yet to be released, says ATSB.

Source: Air Transport Intelligence news