Mark Dickson, 47, an air traffic controller from Troon, Ayrshire, sustained a fatal head injury in the crash on 4 September last year at Portmoak airfield on the shores of Loch Leven near Kinross, the home of the Scottish Gliding Centre.
The single-seat glider, a Schempp-Hirth Nimbus-3 aircraft, crashed as it was being winched into the air - only two seconds after the winch cable had been released, trapping Mr Dickson under the heavy glider.
Mr Dickson, who worked for the National Air Traffic Services at Prestwick Airport, had been gliding for more than 30 years and had gained a gold certificate for his flying.
The AAIB report, published today, states: “At an early stage of the launch the right wing tip contacted the ground, the left wing lifted and the glider cartwheeled to the right before coming to rest, inverted.”
According to the report Mr Dickson had prepared for take off with winds gusting to 18 knots. One student assisted the winch launch by holding the right wing tip steady.
The report states: “The winch operator did not have a clear view of the gliders at the launch area because of a slight rise in the ground, but he could see the gliders as soon as they became airborne.
“During the launch, the wingtip holder was unable to keep pace with the glider for more than a step or two before he had to release the wing. As soon as he let go he saw the right wing drop towards the ground, then lift up again.
“The wing tip then dropped again and the wingtip ran along the ground. He expected the pilot to release the winch cable, but the launch continued with the right wing running along the ground. After a short period, the left wing lifted and the glider briefly became airborne before cart wheeling and coming to rest upside down.
“The situation developed very rapidly, to a point from which the glider was not recoverable.”
According to the AAIB inspectors the total flight time had been around five to six seconds.
“It was assessed that it was around four seconds from the start of the launch until the cable released by which time the glider was in an unrecoverable attitude. It was not possible to establish if the pilot had released the cable or whether the back release mechanism had operated.”
The report continues: “The advice from the British Gliding Association is that if the wing touches the ground during the launch then the pilot should immediately release the winch cable. Although the right wing of the glider contacted the ground at an early stage of the launch, th cable was not released and the launch continued.”
It was possible, said the investigators, that the pilot may not have initially been aware that his wing tip was on the ground.
They state: “This type of glider has a long wing and only a small roll angle is required before the wing contacts the ground. The Nimbus 3 is a heavy glider with a particularly long wing and it may be that there is a greater likelihood of wing touching the ground during take off, perhaps without the pilot being aware of it.
“On this occasion both the wing holder and launch signaller saw the wing touch the ground but events then developed quickly, so it is unlikely that either of them had time to make a ‘stop’ signal. Therefore the responsibility to release the cable would have to rest with the pilot.”
The Scottish Gliding Centre is operated by the Scottish Gliding Union, the largest gliding club in Scotland, and provides year-round flying to both members and many visitors.
The Nimbus-3 first took to the air in 1981. The aircraft is 25ft long with a wingspan of 80ft, and can reach a top speed in flight of 170mph.