Many bombers during WWII had only one pilot. The B17 had two, a pilot and a co-pilot. This arrangement not only made things easier while the aircraft was flying in formation or in combat, but it also allowed the pilots to rotate duties. Flying formation for eight to ten hours was strenuous work. This way, the pilot and co-pilot could swap duties, so that neither one wore himself out and so both could receive time flying formation. The pilot also acted as Crew Commander, with the other crew members of the aircraft falling under his direct command.