Beam Approach Beacon System – BABS – was a homing device used to help pilots land in poor visibility. Radio beacons on the airfield transmitted signals, which were picked up by aircraft on their approach to land.
The Main Beacon at the end of the runway transmitted a signal in the form of a narrow beam. When the pilot was lined up correctly on this beam the signal received was steady and he knew he was heading straight towards the runway. If he was too far to the left or right, the signal received was a stream of dots or dashes and he corrected his course until the signal changed to a steady pulse.
When the aircraft crossed the Outer and Inner Marker Beacons the pilot also detected their distinctive signals, which told him how far he was from the point of touch-down. He used this information to check his rate of descent until the ground came into view and he could make a safe visual landing.
The Airspeed Oxford at RAF Museum Hendon is an example of one of the aircraft used to train pilots in the use of BABS.
Date: May 1945
Collection Ref: X001-6746