Based on the successful Beech Model 18 airliner, the AT-7 was used by the Army Air Forces to train Navigators during World War II and for a number of years after the war. Three students and an instructor were carried on each flight. Each student had a desk similar to the one he would work from in a bomber or transport, and they took turns practicing their navigational skills. The primary difference between these aircraft and a standard Beech 18 is the addition of an astrodome behind the cockpit for the students to use while working on celestial navigation problems.
U.S. Army Air Forces, World War II
Pima Air & Space Museum