THE search was called off last night for Mr Gavin Keen, the trainee pilot from Bon Accord in Aberdeen, who was on board the light aircraft that crash landed in the waters of the Cromarty Firth just after 6pm on Wednesday.

As searchers waited for the Air Accident Investigation Branch (AAIB) to arrive, the pilot/instructor of the plane, Peter Brooks, told of the extraordinary train of events after the aircraft's engine inexplicably failed.

Mr Brooks said the engine of the one-year-old Robin HR200 training aircraft had failed over Easter Ross. He said he and Mr Keen had survived to congratulate each other on a ''text-book'' crash landing as they clung to the wings of the plane. He said they had then swum together the 100 yards ashore close to the Nigg fabrication yard and oil terminal at the mouth of the Cromarty Firth.

They could see the lights of Cromarty on the southern shore and those of a tanker berthed at Nigg on the other. The aircraft had somersaulted and the cockpit was underwater.

Mr Brooks said: ''We thought the aircraft was sitting on the bottom. All three wheels were visible with only the cockpit under the water. Both of us held on to the aircraft, one each wing. After approximately one minute, the aircraft suddenly sank very quickly. We started swimming to the harbour wall. I was talking to Gavin, discussing swimming slowly and steadily to the harbour wall.

''After swimming for a couple of minutes together, Gavin started swimming away from me in a more northerly direction. I said keep going for the wall (at Nigg) but he didn't answer me.'' Mr Brooks got to the sea wall and moved along it until he found a ladder.

''I heard Gavin shout help when I got to the top of the ladder and I shouted back I would get help. I saw lights which I thought were from an office, but they were from the bridge of a tug. I could still hear Gavin shouting. The crew of the tug switched on all their lights and radioed for assistance, and then the helicopter arrived.''

Mr Keen, 24, had already issued a Mad Day call when the plane was still in the air, and it had been received by RAF Lossiemouth who said a helicopter would arrive in eight minutes.

Mr Brooks said: ''After the engine failed we seemed to have so much time, five or 10 minutes it seemed. I had time to complete 'cause of failure' checks, Gavin then completed the same checks. According to the instruments the engine should have been working. I just don't know why the engine failed. I have been flying for 27 years and I can't explain it.''

Mr Brooks said they had left Inverness airport 40 minutes earlier on the first of three, night training flights that Mr Keen, an aircraft handler with Bond Helicopters in Aberdeen, was undertaking to help upgrade his private pilot's licence, to a commercial licence.

Yesterday, Mr Keen's father Roy Keen, who lives in Dingwall at the western end of the Cromarty Firth, said: ''His great love was flying. It was his one ambition to get that licence.'' A decision will be taken by the AAIB whether the aircraft will be raised from the seabed.