In aviation, approach surveillance radar (ASR or SRA) is a type of radar instrument approach provided with active assistance from air traffic control. The only airborne radio equipment required for radar approaches is a functioning radio transmitter and receiver. The radar controller vectors the aircraft to align it with the runway centreline. The controller continues the vectors to keep the aircraft on course until the pilot can complete the approach and landing by visual reference to the surface.

There are two types of radar approaches: Precision (PAR) and Surveillance (ASR). A radar approach may be given to any aircraft upon request and may be offered to pilots of aircraft in distress or to expedite traffic; however, an ASR might not be approved unless there is an ATC operational requirement, or in an unusual situation or emergency. Acceptance of a PAR or ASR by a pilot does not waive the prescribed weather minimums for the airport or for the particular aircraft operator concerned. The decision to make a radar approach when the reported weather is below the established minimums rests with the pilot. PAR and ASR minimums are published on separate pages in the FAA's terminal procedures publication.