Nondirectional Beacon (NDB)
A Non-Directional Beacon (NDB) is a ground-based radio station transmitting in all directions simultaneously (omnidirectional) in the LF/MF frequency range (190–1750 kHz). NDBs are received by the ADF (Automatic Direction Finder) receiver in the aircraft, which displays the magnetic bearing TO the station.
NDB vs. VOR
- NDB: LF/MF; long range over water (ground wave); subject to night effect, coastal refraction, mountain effect; ADF receiver required; bearing TO the station
- VOR: VHF; line-of-sight; not susceptible to same errors; CDI/OBS receiver required; radials FROM the station
NDB Status in Canada
NAV CANADA has been decommissioning NDBs across Canada as GPS/GNSS approaches replace NDB instrument approaches. Many NDBs that were previously the primary approach navaid at remote aerodromes have been replaced by RNAV (GNSS) approaches. Always check the CFS and NOTAMs for NDB operational status before planning to use one.
On the TC Written Exam
NDB navigation, error sources, and ADF technique remain on both PPL and CPL exams. Know: how to track to and from an NDB; error sources (night effect, coastal refraction, thunderstorm); the difference between homing and tracking.