Marker beacons are used along the flight path when approaching an airport and indicate both aurally and visually when the aircraft is directly over the facility.

• A. A low-powered transmitter that directs its signal upward in a small, fan-shaped pattern
• B. A high-powered transmitter with a wide radiation pattern
• C. A ground beacon for taxiway location
• D. A satellite-based transmitter

Answer: (A)

Marker beacons are designed to give a precise overhead cue along the approach by using a low-powered transmitter that directs its signal upward in a small, fan-shaped pattern. This focused vertical radiation ensures the signal is received mainly when you are directly over the facility, providing both a distinctive aural and visual indication to the pilot at the moment you pass the fix. The system is ground-based and tuned for accuracy on the approach path, so the cue is reliable only at that specific location.

The other concepts don’t fit because a high-powered transmitter with a wide radiation pattern would broadcast too broadly and could’t reliably signal overhead position; a ground beacon for taxiway location serves surface navigation, not the approach path; and a satellite-based transmitter would refer to RNAV/GNSS systems, not marker beacons.