Navigation
Navigation content
The navigation paper tests chart work, the wind triangle, great circles and rhumb lines, magnetic variation and deviation, RNAV/PBN, GNSS and inertial systems. You must distinguish track, heading, course and bearing, and apply variation in the correct direction.
Core rules
- True track is the path over the ground; heading is where the nose points; drift is the angle between them.
- Variation east: magnetic is less than true; variation west: magnetic is greater than true. Deviation is the aircraft-specific error.
- A great circle is the shortest path; a rhumb line is a constant track. Use the chart's projection correctly.
- RNAV and RNP rely on area navigation; RNP includes on-board performance monitoring and alerting. Check waypoint fly-by and fly-over logic and database currency.
- GNSS is subject to RAIM, jamming and spoofing; IRS drifts and needs alignment.
Worked example
True track 000°, TAS 100 kt, wind 270°/20 kt. The wind is a crosswind from the left, so the aircraft needs a heading left of track. WCA = sin⁻¹(20/100) ≈ 11.5° left, giving true heading ≈ 348.5°. Ground speed = √(100² − 20²) ≈ 98 kt. With 5°E variation, magnetic heading ≈ 343.5°.
Traps
Applying variation in the wrong direction is a classic error. Do not use TAS to calculate time on a leg with wind. Do not treat a GNSS position as immune to errors. Do not confuse a radial with a bearing.