Radio Navigation
Core framework
Radio navigation covers ground-based aids and their use in the cockpit. Know VOR, DME, NDB/ADF, ILS, and GNSS. Understand how each provides bearing, distance or guidance, and their limitations.
Concepts to master
VOR: radial from station, line-of-sight, cone of confusion overhead. DME: slant range distance. NDB/ADF: bearing to station, affected by static and night effect. ILS: localizer (lateral), glideslope (vertical), markers. GNSS: satellite-based, RAIM. Understand the difference between bearing "to" and "from" a station.
Traps
- Confusing VOR radial (from station) with bearing to station.
- Forgetting DME reads slant range, not ground distance.
- Mixing localizer (lateral) with glideslope (vertical).
- Assuming NDB is immune to interference - it is not.
Rule of thumb
"Radial = FROM the station; bearing = TO the station." Set the OBS to the desired radial and check the TO/FROM flag.
Worked example
You are on the 090° radial from a VOR. That means you are east of the station. To fly to the station, turn to a heading of 270° (the reciprocal).