The grieving family of an RAF pilot who died with his navigator when their Tornado jet crashed into an Argyll hillside said they took comfort from the fact he died "doing what he loved."

Flight Lieutenants Kenneth Thompson, 27, and Nigel Morton, 43, of 43 Squadron, RAF Leuchars in Fife, were on a training mission with another Tornado when their F3 fighter went down at Glen Kinglas on Thursday.

Flight Lieutenant Thompson's family said in a statement that he was passionate about his career in the RAF and that he loved life.

"We, the family, have lost our son and brother, but take some comfort from the fact that he died doing what he loved - flying. Our thoughts are also with the family of his navigator, friend and colleague at this most difficult time for us all," they said.

Flight Lieutenant Morton's family paid tribute to a "beloved father and husband, son, brother and son-in-law" who was respected by all who worked with him. "Our thoughts are with Kenny's family at this terrible time," the family said.

Pilot Flt Lt Thompson was from the Glasgow area and Weapon Systems Officer Flt Lt Morton was from Fife.

Yesterday, as an investigation continued in an effort to determine the cause of the tragedy, Defence Secretary Bob Ainsworth described his sadness. He said: "I would like to express my deepest sympathies to the families of the two aircrew as they face this shocking loss."

Wing Commander David Hazell, 43 Squadron's commanding officer, said: "Their deaths are a huge loss to the squadron and the Tornado F3 Force as a whole.

"However, it is nothing compared to that suffered by their families. Our thoughts and prayers are with them at this dreadful time."

The jet came down at around lunchtime near the Rest and Be Thankful beauty spot on the A83 Arrochar to Inveraray Road, north-west of Loch Lomond.

Search-and-rescue helicopters from the HMS Gannett naval base and RAF Lossiemouth were scrambled to search the area for the wreckage. The RAF has launched an inquiry to establish the cause of the crash.

Air Commodore Harry Atkinson, Air Officer Scotland and Officer Commanding Royal Air Force in Leuchars, paid his own tributes to the men.

Flt Lt Morton had been one of the most experienced navigators on the Tornado F3 Force, with nearly 3000 hours on the aircraft.

"Flt Lt Nige Morton was a wonderful, energetic and professional member of our team. Constantly enthusiastic and steeped in experience, he has been a highly valued member of his squadron and RAF Leuchars. Well-known by everyone, Nige will be sorely missed," he said. "My thoughts are with his wife and son at this desperate time."

Flt Lt Thompson was seen as a young pilot with an extremely bright future, who when not in a Tornado F3 would be flying his own aircraft around Scotland. Trips by air to Tiree with Kenny, as he was known to his colleagues, were the talk of the summer at Leuchars "Flt Lt Kenny Thompson was a bright and effervescent young man with a zest for life," added Air Commodore Atkinson.

"I shall remember him for his constant smile and inspirational attitude that brought much happiness to all. He will be dearly missed by all who have known him. My thoughts are with his family."

Squadron Leader Wayne Smith, the crew's flight commander on 43 (Fighter) Squadron, said Flt Lt Thompson was the "epitome of a fighter pilot and at the heart of 43 (Fighter) Squadron".

"No-one was more enthusiastic, professional and committed to flying than he. His great attitude was contagious," he added.

"It is with some consolation that his squadron friends know that he died doing what he enjoyed the most, flying a fast jet on a beautiful summer's day in the west of Scotland."

Flt Lt Morton was a veteran of operations in Bosnia and Iraq and was a "consummate professional, a talented weapons systems officer and a good friend", added Sqn Ldr Smith.

"He was pivotal to squadron flying operations. He single-handedly ran the flying programme and manning."