Aeronautical beacons that can be seen from all directions. They identify airports and landmarks and mark obstructions. Green-coded flashes, not exceeding 40 flashes or character elements per minute, identify land airports. Yellow-coded flashes, not exceeding 40 flashes per minute or constant flashes of 12 per minute, identify water airports. Red flashes, 12 to 40 flashes per minute, mark hazards.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved