The Grumman OV-1 Mohawk was developed for the US Army for the observation role, according exceptional visibility to the two man crew and able to carry a variety of cameras, radar and infra-red detection systems for photo-reconnaissance and electronic surveillance.

The L-5 Sentinel was developed from the Stinson Voyager light touring monoplane and, when compared, the Sentinel had more power and a strengthened airframe to enable it to be flown in the role of air-observation post under combat conditions.