Navigation
The Navigation paper tests dead reckoning, pilotage, chart reading, the magnetic compass and radio-navigation aids. You must convert between true, magnetic and compass directions, calculate heading and ground speed from a wind triangle, and monitor position and fuel throughout the flight.
Charts and direction
Latitude and longitude give position. Charts show true tracks; variation converts true to magnetic; deviation converts magnetic to compass. The sequence is True Virgins Make Dull Company: True ± variation = Magnetic; Magnetic ± deviation = Compass. West variation is added when going from true to magnetic; east deviation is subtracted when going from magnetic to compass.
Dead reckoning
Ground speed = distance ÷ time. Heading = track ± drift. ETA must be updated with actual wind. Pilotage uses ground features; dead reckoning uses calculated heading, time and fuel. VOR gives radial information, NDB gives bearing, GNSS gives position; none removes the need to monitor.
Worked example
True track 090°, variation 12°W, deviation 3°E. True to magnetic: 090 + 12 = 102°M. Magnetic to compass: 102 - 3 = 099°C. If ground speed is 90 kt, a 180 NM leg takes 2 hours; at 30 L/h you need 60 L plus reserve.
Traps
Applying variation in the wrong direction; using TAS instead of ground speed; forgetting UTC is local minus four hours in Mauritius; and trusting GPS without a chart and time check.