Appendix A
Instrument Flight
GLOSSARY
A
Airport Advisory Area: The area within ten statute miles of an airport without a control tower or where
the tower is not in operation and on which a flight service station is located.
Airport Elevation/Field Elevation: The highest point of an airport’s usable runways measured in ft MSL.
Airport Surveillance Radar (ASR): Radar providing position of aircraft by azimuth and range data
without elevation data. Used for terminal approach and departure control. (See Surveillance Approach.)
Air Route Traffic Control Center (ARTCC): A facility established to provide traffic control service to IFR
flights operating within controlled airspace, principally during the enroute phase of flight.
Airway: Class E airspace or portion thereof established in the form of a corridor equipped with radio
navigational aids.
Alert Area: An airspace which may contain a high volume of pilot training activities or an unusual type of
aerial activity, neither of which is hazardous to aircraft.
Alternate Airfield: An airport specified in a flight plan to which a flight may proceed if the destination is
below minimums or safety considerations preclude a landing.
AOA: Angle of attack.
AOB: Angle of bank.
Approach Control: A term used to indicate an air traffic control unit providing approach control service,
without specifying the unit.
Approach Control Service: Service provided by a terminal area traffic control facility for arriving and/or
departing IFR flights and, on occasion, VFR flights.
ASR: See Airport Surveillance Radar.
ATC: See Air Route Traffic Control Center.
Automatic Terminal Information Service (ATIS): A continuous broadcast of recorded, non-control
information in selected high activity terminal areas. Its purpose is to improve controller effectiveness and
to relieve frequency congestion by automating the repetitive transmission of essential but routine
information.
Page 139
(12-00) Original
Previous Page
