MOUNTAIN rescuers braved appalling conditions to search for the wreckage of a light aircraft feared to have crashed in the Cairngorms yesterday.

The pilot, who is not believed to have been carrying any passengers, was flying from Carlisle to Wick when he was last heard from after he radioed commercial jets in the area to indicate he was in difficulty.

Eyewitnesses at the Ptarmigan restaurant at the top of the Cairngorm funicular railway near Aviemore reported seeing the Piper aircraft before hearing a loud bang.

Last night, six teams of mountain rescuers were being flown by helicopter around a 50-square-mile area where radar contact was lost with the pilot.

RAF Kinloss spokesman Michael Mulford said: "We are now investigating reports we regard as reliable that the aircraft was seen heading south in the area of the Ptarmigan restaurant.

"The sighting was followed by reports of a loud bang. In terms of time and place these reports are consistent with previous information about the aircraft losing contact with radar and radio.

"The search is now concentrated in an area of about 50 square miles. Mountain rescuers are being ferried by helicopter to several points in the area. Weather conditions are still bad with snow showers and freezing temperatures."

Earlier, two helicopters from RAF Lossiemouth and Boulmer, in Northumberland, carrying six mountain rescuers from the Glenmore and Braemar teams, were sent to the area eight miles east of the ski resort.

Because the conditions prevented an aerial search, teams were winched to the ground to interview hillwalkers as potential witnesses.

About 100 people were involved in the search, which was co-ordinated by the Aeronautical Rescue Co-ordination Centre at RAF Kinloss.

Teams from RAF Kinloss and Leuchars had their own crews on standby in case they were needed.

Mulford said: "The conditions, with a lot of snow, and visibility were very bad.

He said the pilot, whose identity has not been released, would have faced "tricky" decisions about whether to fly above or below the snowstorm over the mountainous terrain.

"In those conditions, he must have had to take a decision whether to go above or below it. It's not easy in a light aircraft, given the terrain below.

"He is being treated as missing, but as time goes by we begin to fear the worst."

One aviation expert speculated that as the plane was US registered, the pilot may have planning to re-fuel in Wick, the Faroe Isles and Reyjkjavik as he flew across the far north of the Atlantic.