Two helicopters came within 100ft of a mid-air collision over Shetland, it was revealed yesterday.
The pilot of one aircraft, understood to be involved in ferrying oil rig workers, threw the machine to one side when he saw the other aircraft below him as he descended.
The pilot of the other helicopter, an EC135T2, did not see the other aircraft at all, a near-miss investigation discovered.
It was only by chance that a crash was avoided, said the report.
The incident was assessed as the highest risk rating – Category A – in a report released by the UK Airprox Board.
The EC135T2 – operated by Bond Offshore Helicopters – was heading from the northern tip of the islands back to Tingwall Airport near Lerwick with four people on board when it passed 100ft below a Sikorsky S92 owned by Bristow Helicopters Ltd which was on approach to Scatsta Airport on the north of the main island.
The pilot of the EC135T2 did not see the other aircraft and the two helicopters narrowly avoided colliding as they flew over the Burravoe area.
The S92 was descending when the pilot noticed the other helicopter approaching from below in the opposite direction at around noon on September 16 last year.
The S92 pilot made a sharp left-hand turn to avoid hitting the aircraft. He told the UK Airprox Board he had no warning until after the helicopter had passed.
Under the levels of service in place that day the pilots, rather than the air traffic control service, were responsible for avoiding other traffic.
The Bond helicopter pilot contacted air traffic control five minutes before the incident and were told about the other aircraft and to remain “well to the east”.
The board members found the cause of the incident was a late sighting by a the S92 pilot and non-sighting by the EC135T2 pilot.
They stated: “Although noting that the S92 pilot had taken an avoiding action turn on sighting the EC135 below him, it was considered that this action probably occurred as the EC135 was already passing the S92. Consequently, it was agreed that the turn probably did not measurably increase the separation between the two helicopters. The board agreed unanimously that, because separation had been reduced to the minimum and chance had played a major part in events, nothing more could have been done to improve matters and the risk was assessed as Category A.”