Navigation and Radio Navigation
Navigation fundamentals
You must be comfortable with dead reckoning, wind triangle, magnetic variation and deviation, chart reading, and radio navigation aids: VOR, NDB/ADF, DME, ILS, GNSS, and RNAV.
Key concepts
- True vs magnetic vs compass: True ± variation = magnetic; magnetic ± deviation = compass. "East is least, west is best" for variation when converting true to magnetic.
- Wind triangle: heading, track, wind correction angle (WCA), groundspeed.
- VOR: radial from station; CDI centred with TO/FROM; reverse sensing.
- NDB/ADF: relative bearing, QDM/QDR.
- ILS: localiser (lateral), glideslope (vertical), markers.
- GNSS/RNAV: waypoint navigation, RAIM, integrity.
Traps
- Applying variation in the wrong direction (true→magnetic vs magnetic→true).
- Confusing radial FROM vs bearing TO.
- Forgetting deviation (compass error) after variation.
- Mixing QDM (magnetic bearing TO) and QDR (magnetic bearing FROM).
Worked example / rule of thumb
True course 090°, variation 10°E → magnetic course = 090 − 10 = 080°. If deviation is 2°W, compass course = 080 + 2 = 082°.
Rule of thumb: "East is least" - subtract easterly variation when converting true to magnetic.