Also found in: Acronyms.
fan marker[′fan ‚märk·ər]
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
A highly directional radio signal transmitted vertically upward from a transmitter located along a navigational radio-range, as in an instrument landing system (ILS). The output of a fan marker is heard only when the aircraft is directly above the transmitter, thus indicating to the pilot his exact position. A fan marker is keyed for identification. Also called a fan-marker beacon.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved