A simulated “PRESS DOOR OPEN” warning is displayed on the Multifunction Display Unit at the C-5M flight engineer’s panel trainer Jan. 28, 2020, at the 373rd Training Squadron, Detachment 3 on Dover Air Force Base, Del. During a recent mission dubbed Reach 190, an aircrew from the 9th Airlift Squadron had a “PRESS DOOR OPEN” warning appeared on the pilot’s, copilot’s and flight engineer’s Multifunction Display Units, caused by a crew door “NOT LOCKED” light indication on the C-5M left-hand forward loadmaster control panel while in flight. (U.S. Air Force photo by Roland Balik)