observation and surveillance aircraft

observation and fields of fire, avenues of approach, key and decisive terrain,obstacles, and cover and concealment (OAKOC)

surveillance, high- and low-altitude surveillance

anti-aircraft artillery observation aircraft

observation point / observation post (OP)

surveillance and target acquisition aircraft system

surveillance, under surveillance

observation aircraft (O; obsn acft)

observation aircraft

artillery observation aircraft

aircraft track and balance (adjusting balance of aircraft)

pilotless aircraft surveillance system

surveillance aircraft

drone surveillance aircraft

surveillance aircraft flight control system

command-and-observation post

SLOCTOP (security, location, communication, targeting, observation, and position improvement)

observation and fields of fire

artillery reconnaissance and observation

instrumental observation and survey battery

Space System for Tracking Ships and Aircraft in Distress – Search and Rescue Satellite (COSPAS-SARSAT)

chemical, biological, radiological and nuclear surveillance

high- and low-altitude surveillance

intelligence, surveillance, and reconnaissance (ISR)

joint surveillance and targeting attack radar system (JSTARS)

reconnaissance and surveillance assets

reconnaissance and surveillance missions

reconnaissance, surveillance, and target acquisition (RSTA)

special surveillance and reconnaissance

surveillance and attack system

surveillance and reconnaissance

Unmanned Carrier Launched Airborne Surveillance and Strike System (UCLASS)

intelligence, surveillance, target acquisition, and reconnaissance (ISTAR)