Abstract: An observer door unit which can be installed and removed from an aircraft doorway during flight, especially designed for use in aerial search and rescue operations. The unit, in its simplest form, consists of a portable base, which can be loaded on and off the aircraft, on which is mounted a combination door and window unit. Generally the door and window unit is pivotally mounted on the base to facilitate storage and handling on the aircraft. The base is provided with quick release locks to secure it to the floor of the aircraft and the door has locks to secure it to the doorway. A seat is generally slidably mounted on the base for the comfort of the observer.