Aircraft miss each other by 5m above Darwin
TWO Cessna aircraft came within a split-second of colliding at above 6000ft in Darwin airspace.
An investigation by the Australian Transport Safety Bureau found the two aircraft, carrying four people between them, missed each other by less than 5m in a terrifying near miss 46km southwest of Darwin two years ago.
An inaccurate altitude reading and a series of poor decisions - starting at takeoff and continuing until the moments before the planes almost collided - have been identified as the causes for the near miss, the ATSB investigation found.
Destined for Port Keats, the Hardy Aviation and Chartair charter aircraft took off just one minute apart from a Darwin Airport runway about 8am on January 6, 2017.
Not long after takeoff, after tracking at a safe distance, the two pilots lost sight of each other. About 46km into the flight path, the Chartair Cessna, carrying one pilot and no passengers, told the ATSB the Hardy Aviation Cessna, carrying one pilot and two passengers, "came from the left top corner of his windshield across the nose to the bottom right in front of him and filled the windscreen".
"He estimated the two aircraft passed 3-4 metres apart," the investigation found.
According to the Hardy Aviation pilot, the Chartair plane "came within 5m" of collision. The investigation recorded the Hardy Aviation pilot as reporting they were "surprised by the proximity" to the Chartair plane.
The near miss, the investigation found, was due to a warning alert sounding too late.
"Neither pilot had an appreciation of just how close the aircraft were until they re-sighted each other as they passed in proximity," the investigation found.
A "discrepancy" between one plane's radar altitude and "actual aircraft altitude" was also found in the investigation, putting the aircraft 500 metres vertically closer to the other aircraft than displayed.
The investigation found that had air traffic control initially verified the initial altitude of the craft on first contact, the radar discrepancy, and near miss, could have been avoided.
The ATSB also found that neither aircraft was "equipped with any Airborne Collision Avoidance System (ACAS) technology".