Career
Born in Hanoi, Vietnam, he was a pilot for the Vietnam People"s Air Force who rose to the rank of Captain and flew many combat missions during the Vietnam War. Liêm was selected as backup of Phạm Tuân who was the first Vietnamese and the first Asian in space on the Soyuz 37 mission. In 1981, he was killed in a MiG-21 aeroplane crash during a training flight over the Gulf of Tonkin off the coast of northern Vietnam.