Navigation
Navigation tests position fixing, chart work, radio navigation aids, GNSS and performance-based navigation. Expect calculations involving track, drift, DME and the 1-in-60 rule.
Charts and track
- True track is measured from true north; magnetic track uses variation. Deviation is aircraft-specific and applies to the compass.
- The 1-in-60 rule: a 1 nm off-track error after 60 nm corresponds to 1° of track error.
- Great circles are the shortest route on a sphere; rhumb lines cross meridians at a constant angle.
Radio navigation and PBN
- VOR gives radial/bearing; DME gives slant range, which reads high near the station.
- NDB/ADF is affected by night effect, static and coastal refraction.
- GNSS needs RAIM or SBAS integrity monitoring; PBN specifies RNAV/RNP accuracy.
Worked example
After 40 nm you are 2 nm left of track. Track error = (2/40) × 60 = 3°. To regain track over the next 40 nm, use a closing angle of 3°, so fly a heading 6° right of the original track until back on track, then return to the original heading.
Traps that cost marks
- Applying variation to a magnetic heading that already includes it.
- Treating DME as ground distance; it is slant range.
- Forgetting RAIM prediction for GNSS approaches.