Navigation
Navigation tests dead reckoning, the wind triangle, charts, magnetism, time and electronic navigation. The key skill is moving correctly between true, magnetic and compass directions and between heading, track and ground speed.
Direction and distance
Track is the path over the ground; heading is where the nose points. Variation is the angle between true and magnetic north; deviation is the error in the compass. Convert true to magnetic with east variation subtract, west variation add. One minute of latitude is one nautical mile; one degree of longitude is 60 nm at the equator but less at higher latitudes.
Wind triangle
The wind triangle relates track and ground speed to heading and true airspeed. Crosswind determines drift; headwind or tailwind changes ground speed. Always draw the wind from the direction it comes from, and apply the wind correction angle into the wind.
Worked example
Track 000 true, TAS 100 kt, wind 270/20. The wind is from the west, so it pushes the aircraft east of track; heading must be west of north. Crosswind component 20 kt. Wind correction angle = arcsin(20/100) = about 11.5 degrees left, so heading 348.5 true. Ground speed = 100 x cos(11.5) = about 98 kt. With 12 degrees west variation, magnetic heading = 348.5 + 12 = 000.5 magnetic. Over 98 nm the flight takes one hour.
Charts and time
Use the chart scale for distance and the nearest meridian for true direction. Convert UTC to local time carefully; Mauritius is UTC+4. GPS gives position, track and ground speed, but it is not a substitute for monitoring fuel and chart position.
Traps
Applying variation to the wind; using heading instead of track in the wind triangle; adding west variation when converting true to magnetic; confusing UTC with local time.