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Charts and the Earth
Know the properties of common projections: Mercator is conformal with a straight-line rhumb line but greatly exaggerated scale near the poles; Lambert conformal conic is used for many topographical and airway charts and preserves angles. Distinguish great-circle tracks (shortest distance) from rhumb lines (constant track). Understand latitude and longitude, UTC and local time, sunrise/sunset, and the use of the scale and grid.
Magnetism and the wind triangle
True heading, magnetic heading, compass heading, track and drift must be kept distinct. Variation converts true to magnetic; deviation converts magnetic to compass. A useful memory is “east is least, west is best” for magnetic values: for easterly variation subtract it from true, for westerly add it. The wind triangle converts between heading, true airspeed and track, groundspeed. Know VOR, NDB/ADF, DME, ILS, GNSS, RNAV/PBN and RNP, and the errors and limitations of each.
Worked example
True track 090°, variation 10°E, deviation 3°W. Magnetic track = 090 − 10 = 080°. Compass heading = 080 + 3 = 083°. Always apply variation and deviation in the correct order and direction.
Rule of thumb
True to magnetic: easterly variation subtract, westerly add. Magnetic to compass: easterly deviation subtract, westerly add.