Pfeifer started his aviation career as a bookkeeper at Boeing Aircraft in Wichita. While at Boeing, he got his pilot’s license and joined the U.S. Army Air Force as an observation pilot. The observation pilots were tasked with flying the wounded soldiers to hospitals, running mail, ferrying commanders to meetings, and taking photos of troop positions. Pfeifer received the Distinguished Flying Cross for rescuing a downed pilot from his group. He became a test pilot on the Mohawk, a short landing turbojet that the Army was considering for use in Vietnam. He was also a test pilot on the Iroquois “Huey” helicopter. Pfeifer eventually worked at the Pentagon on developmental projects with manufacturers such as Boeing. He was the recipient of the Distinguished Flying Cross, Bronze Star, and Purple Heart.