Pilots of smaller Australian aircraft have been urged to fit collision avoidance technology after two charter flights came within five metres (16.4ft) of hitting each other.
The aircraft involved, a Cessna 210 and a Cessna 206, were operating the flights in December, 2017 under Visual Flight Rules (VFR) from Darwin Airport to Port Keats, about 390kms from Darwin.
Both aircraft were equipped with Mode C transponders and the Cessna 206 had two passengers on board.
The aircraft departed in quick succession and planned to track at 8500ft. They had been informed by air traffic control of each other’s presence and plans, according to a report released Thursday by the Australian Transport Safety Bureau.
The Cessna 210 was the trailing aircraft, but it was traveling faster than the C206 and as the two converged the pilot of 206 lost sight of the other plane.
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“With the wing structure obscuring the view, the pilot advised air traffic control but took no further action to ensure segregation between the aircraft as they drew nearer,’’ the ATSB said.
“The situation culminated with the aircraft reportedly coming within five metres of each other as they passed.
“Owing to a combination of radar accuracy/resolution and the inaccuracy of the displayed height of the C210, the controller issued a safety alert only after the near-collision had already occurred.”
Investigators said the limitations of see-and-avoid — the primary means by which Visual Flight Rules aircraft prevent collisions — were well known.
They said recent advances in airborne collision avoidance system technologies had made them viable for general aviation aircraft.
“They provide valuable information to alert pilots of other aircraft in their proximity and can direct the pilot to take avoiding action, thereby reducing the risk of collision,’’ they said.
Groups representing private pilots have complained about the cost of adopting new technology but authorities say the price has been dropping and new options are becoming available.
The Australian aviation regulator is also proposing to make it easier for small planes to be fitted with less expensive equipment that would increase awareness of other aircraft traffic.
The report notes that a near-collision between a Saab 340 and a glider in 2016 prompted a proposal by an Australian industry group to the Civil Aviation Safety Authority about standards for satellite-based ADS-B technology in general aviation aircraft.
“Following industry consultation, CASA is proposing to relax the equipment and installation standards for ADS-B fitment in VFR aircraft,’’ it said. “The aim is to make it cheaper and easier for aircraft operating under VFR to purchase and use the technology.”
CASA has been testing cheaper ADS-B equipment as part of this process.
One pilot told AirlineRatings that almost all general aviation and charter pilots now used an Apple or Andriod electronic flight bag that could take an input from an ADS-B transceiver costing as little as $1119.
He said this was a small fraction of the cost of fully-approved equipment and well within the reach of small aircraft operators and pilots.
“Because they are for VFR use and operate air-to-air, they can offer a considerable safety enhancement without necessarily needing the intervention of ATC,” he said.
“So they can be effective even in more remote areas where ATC radar isn’t available, provided both aircraft in the conflict pair are equipped.
“Pilots using these devices do/must not solely rely on them for separation – because they are flying VFR, they must also sight the traffic – but the devices give an early, highly accurate warning of upcoming conflicts and where to look, long before the traffic can be seen.
“It seems extremely unlikely these two aircraft would have ever got so close if they were equipped.”
An added advantage was that the devices also make small planes visible to appropriately equipped larger aircraft, he said.
