Instrument Landing System (ILS) Explained - YouTube
VHF SPECIFICATION OF A POSITION MARKER
ILS – Instrument Landing System – ABCD.XXX
Marker beacon | Article about marker beacon by The Free Dictionary
Testing Marker Beacon with the R&S®CMA180 Radio Test Set - YouTube
Marker Beacon System * Function The marker beacon system is a radio navigation aid which determines the distance between the aircraft and the runway threshold. The system provides visual and aural indications