Air Commodore John Mitchell was the navigator on the prime minister's personal aircraft, called Ascalon.
He and the rest of the crew flew Churchill, codenamed "The Owner", to the Yalta and Tehran conferences.
Author Sean Feast, with whom Air Cmdr Mitchell collaborated on his 2009 autography, described him as a "remarkable man".
The London-born RAF volunteer had flown bombing raids over Germany and Italy early in the war and survived when his Armstrong Whitworth Whitley bomber ditched in the Channel while returning from Genoa on only his third mission.
Air Cmdr Mitchell was awarded the Distinguished Flying Cross and spent a short time in the United States before returning in 1942 and being assigned to Ascalon.
During that time he flew Churchill to the historic summit meetings at which Churchill, Soviet leader Joseph Stalin and US President Franklin D Roosevelt decided the conduct of the war and how the post-conflict world would be divided up.
Mr Feast said: "It was only after I'd met John a few times through friends that he mentioned casually that he'd flown with Winston Churchill during the war.
"I knew then it would make a great story and so it proved. He was a lovely man in every way, witty, charming and kind.
"We would go to a pub in Boldre, near his New Forest home, and spend the afternoon laughing. He was one of life's characters."
As well as flying Churchill, Air Cmdr Mitchell also flew King George VI on several occasions and was later made a Lieutenant of the Royal Victorian Order (LVO).
After the war he remained in the RAF as an instructor, a role which saw him fly over the North Pole, before being stationed in Moscow as an attachÃ©, working in intelligence and rising up the ranks to Air Commodore.
The Bomber Command veteran retired to the New Forest town of Lymington in Hampshire.
A member of Winston Churchill's personal flight crew during World War Two has died aged 97.