Navigation
What the exam tests
Navigation tests dead reckoning, chart reading, magnetic variation and deviation, the wind triangle, groundspeed, heading, fuel and time, and the use of NDB, VOR, DME, GNSS and area navigation.
Core rules
- True track is measured on the chart; magnetic track = true track corrected for variation; compass heading also corrects for deviation.
- Variation east, magnetic least: subtract easterly variation when converting true to magnetic. Variation west, magnetic best: add westerly variation.
- The wind triangle relates true heading, true airspeed, wind direction/speed, track and groundspeed.
- Drift is the angle between heading and track; it must be applied in the correct direction.
- GNSS gives position and groundspeed but does not replace map reading, fuel monitoring or awareness of RAIM/serviceability.
Worked example
True track 090°, variation 6°W, deviation 2°E. Reasoning: variation west is added to true track, giving magnetic track 096°. Deviation east is subtracted from magnetic heading, giving compass heading 094°. If the wind causes 5° left drift, the heading must be turned 5° right of the track-derived heading. Always state whether the result is track or heading.
Traps
Adding variation in the wrong direction; confusing track with heading; applying deviation to the chart; forgetting drift; using TAS as groundspeed.