A system for providing ground location messages to an aircraft equipped with a
Marker receiver, comprising a plurality of message transmitting devices arranged
at different locations, each message transmitting device comprising:
- a radio transmitter (81, 82) operating at standard Marker Beacon
frequency and connected to antenna means arranged to radiate a signal within a
predetermined area at the location;
- message storage means (76, 77) connected to the transmitter for
storing a voice message to be transmitted thereby; and
- detector means (72) for detecting the presence of an aircraft
within said predetermined area and for actuating the transmitter to transmit the
voice message in response to detection of an aircraft.