A search and recovery operation is due to resume as two Tornado jet crew remain missing after the planes came down off the coast of Scotland.
One member of air crew has died, two others are missing and a fourth is in a serious but stable condition in hospital.
The man who died, whose name has not yet been released, was an officer from 15 (Reserve) Squadron, based at RAF Lossiemouth in Moray.
There is "no expectation" of recovering the missing people alive, Group Captain Ian Gale, the station commander at the RAF base, said, after the Tornado GR4s went into the Moray Firth.
The search was called off on Wednesday because of "extremely poor" weather conditions in the area.
Mr Gale said: "The operation will be resumed as a recovery operation as soon as possible, but we must be realistic: given the length of time that has elapsed since the accident, there is no expectation of recovering missing personnel alive. The Royal Air Force is in contact with the next of kin of all those involved."
He added: "Clearly, this incident will be subject to full investigation, and a service inquiry will be led by the Military Aviation Authority.
"It is important that we establish the facts of what happened and it is vital that the investigation is allowed to take its course. But the priority now is to ensure that the families of those involved receive the support they need at this most difficult of times."
The RAF ensign at the entrance to the Lossiemouth base was lowered to half-mast and there were no flights in and out of the base on Wednesday.
Prime Minister David Cameron said: "Our thoughts should be with the friends, family and colleagues of those involved. The circumstances still remain uncertain but it's clearly a very serious incident. The investigation is ongoing and more details will be released by the RAF in due course."