The Australian Transport Safety Bureau (ATSB) released its initial investigation into the Sept. 28, 2012, ATC error that occurred 25 miles south-southwest of Williamtown, New South Wales. At 0801 EST an Airservices air traffic controller at the Brisbane ATC complex in Queensland assumed responsibility for airspace sectors extending from 45 nm north of Sydney to near Coffs Harbor in New South Wales, a distance of about 300 nm. The airspace included a number of one-way airways that had previously been split vertically between two control positions at 12,500 feet.

On accepting responsibility for the now-combined airspace, the oncoming controller failed to update the altitude filter on his computer display affecting the airspace above FL125. At 0802, on the incorrect assumption that a Boeing 737 was landing at Williamtown, the controller inhibited the aircraft’s flight data record for the remainder of its trip between Sydney and Brisbane. At the time the 737 was 22 nm southwest of Williamtown and climbing to FL390. This meant that most of the normal aircraft data–airspeed, altitude and destination–were no longer visible on the controller’s screen.

It was only through luck that no actual loss of separation occurred due to the error.

The ATSB will issue a final report by June 2013.