Klaus-Dietrich Flade was born on 23 August 1952 in Büdesheim, near the Belgian border. He served in the military from 1974 to 1976 where he completed both his officer and aircraft mechanics training. He then studied for a degree in Aerospace Engineering at the University of the Federal Armed Forces in Munich (Universität der Bundeswehr München).
Prior to commencing his training as a test pilot in England in 1988, Flade had been a pilot of both single and multi-engine high-performance aircraft for eight years. Flade became a member of the German astronaut team in October 1990 and was involved in the preparation of the Mir '92 mission, where biomedical experiments were to be performed.
Flade lifted off on 17 March 1992 for a week-long stay in orbit with his colleagues and a special guest. The mouse from popular children's television programme 'Die Sendung mit der Maus' (literally, 'The programme with the mouse', renamed 'Mouse TV' for English-speaking audiences) accompanied the crew on their mission. Dressed in a silver space suit, she floated through the Russian Mir space station. This event was beamed live to viewers on Earth and the tradition was continued five years later on the Mir '97 mission, when Reinhold Ewald brought along 'Hein Blöd', a character from the same programme.
DLR assumed all payload operation and astronaut supervision duties for the Mir '92 mission.
Flade became an Airbus test pilot following the successful conclusion of the mission. He lives and works in Toulouse, France.