Whistling Beacons Mark Airfield for Blind Landings (Dec, 1933)
Whistling Beacons Mark Airfield for Blind Landings
HIGH pitched whistles to designate boundaries of an airport make it possible for a pilot to make a blind landing, recent experiments have shown.
The newly designed whistles, called sonic marker beacons, send out fan shaped beams of sound by means of which the aviator can determine definitely the length of the airfield. The pilot, guided to the airport by a radio beacon, selects an altitude of 2,000 feet and within 500 feet of the boundary line picks up the beacon sound with special listening equipment.
Sound dies away 500 feet inside each end of the field, indicating its length.