Born in Sweden, Gravell joined the Royal Canadian Air Force on 15 March 1941. On a routine training flight in Alberta, the Tiger Moth he was in plunged to the ground and burst into flames. A severely injured and badly burned Gravell attempted to rescue the pilot. Leading Aircraftman Gravell died from his burns and was posthumously awarded the George Cross.
His citation reads “The King has been graciously pleased, on the advice of Canadian Ministers, to approve the posthumous award of the George Cross to the undermentioned:-Leading Aircraftman K. M. Gravell (deceased), Royal Canadian Air Force.In November, 1941 a training aircraft crashed and immediately burst into flames. Leading Aircraftman Gravell, who was under training as a wireless air gunner, managed to extricate himself from the wreckage and get clear. In spite of the intense shock caused by the loss of one eye and severe burns, suffered at the time of the crash, Leading Aircraftman Gravell’s first and only thought was for the welfare of his pilot. The pilot was still in the aircraft and Gravell ignoring his own serious injuries and the fact that his clothes were ablaze attempted to get back to the flaming wreckage to pull him clear. He had barely reached the aircraft when he was dragged away and rolled on the ground to extinguish the flames which had, by this time, completely enveloped his clothing. Leading Aircraftman Gravell subsequently died from his burns. Had he not considered his pilot before his own safety and had he immediately proceeded to extinguish the flames on his own clothing, he would probably not have lost his life.”