Although today sometimes a crewed aircraft is still utilised for aerial observation, industry and the military use both satellites and remotely piloted vehicles for this function.
[1] The first recorded RAF "kill" of the Second World War, on 20 September 1939, was by air observer Sergeant F. Letchford, aboard a Fairey Battle, flown by Flying Officer L.H.
[2] Observers were also issued with weapons, and expected to engage with enemy aircraft in the early days of military aviation.
These O-1 Bird Dog, O-2 Skymaster and OV-10 Bronco pilots would slowly fly over an area and direct bombing by radio to fast-moving jet aircraft.
Observer is still the term used in the Royal Navy's Fleet Air Arm (FAA) for non-pilot aircrew officers.