observation aircraft (O; obsn acft)

observation battalion (Obsn Bn)

training aircraft (tng acft) / trainer aircraft

aircraft (acft, A/C )

attack aircraft (atk acft, A)

ground-attack aircraft (gnd atk acft, A)

heavier-than air aircraft (HTA acft)

lighter-than-air aircraft (LTA acft)

military aircraft (mil acft)

reconnaissance aircraft (recon acft, R)

anti-aircraft artillery observation aircraft

observation point / observation post (OP)

observation aircraft

observation and surveillance aircraft

artillery observation aircraft

aircraft accident (flight accident; aircraft mishap)

aircraft armaments / aircraft weapons

aircraft accident / flight accident, aircraft mishap

aircraft mishap / flight accident, aircraft accident

aircraft modernization / aircraft upgrade

aircraft track and balance (adjusting balance of aircraft)

aircraft upgrade / aircraft modernization

aircraft weapons / aircraft armaments

flight accident / aircraft accident, aircraft mishap

low flying aircraft / low-flying aircraft

close observation

command-and-observation post

forward observer (FO), forward observation officer; (artillery) observer / spotter

hostile observation

infrared night vision observation device

observation facilities

observation flight

observation patrol