The original arrangement sweeps a narrow radio beam around the carrier once per minute. Aircrew listen for the point at which the signal is strongest and compare that moment with a watch synchronized to the ship's chronometer. Treating the watch face as a circle of bearings gives a reciprocal direction back to the carrier, which can be refined as the aircraft closes from the roughly fifty-mile reception range. The method demands skill and yields only a rough bearing, but it is rugged and reliable enough to turn an otherwise invisible moving ship into a usable homing area. That guidance also lets the carrier show hooded landing lights only through a narrow sternward arc instead of advertising the whole ship at night. The system links radio direction finding directly to safer, more tactically discreet night carrier operations.
Notable Point · 6:05-9:03
How a rotating beacon guides an aircraft home
A one-revolution-per-minute beam and a synchronized watch give an aircraft a reciprocal bearing on its carrier from roughly fifty miles away.