Navigation Planning, Tracks and Time Calculations
The triangle
Navigation planning is the wind triangle made practical. True track and true airspeed are known; wind velocity is forecast; you derive heading and groundspeed. Then convert true to magnetic using variation, and magnetic to compass using deviation. Know the sign conventions: variation east, magnetic least; variation west, magnetic best. Be able to work the triangle both ways: given heading and true airspeed plus wind, find track and groundspeed, and given required track and groundspeed, find heading and true airspeed.
Time and distance
Time equals distance divided by groundspeed. Be fast with the mental arithmetic and with the navigation computer. Understand the effect of wind on a leg and on the whole route: a headwind outbound and tailwind inbound does not cancel out over an out-and-back, because the time spent in the headwind is longer.
Traps
Examiners test whether you use track or heading when applying wind, and whether you apply variation before or after drift. Another classic is the out-and-back problem, where the average groundspeed is the harmonic mean, not the arithmetic mean. Watch for questions mixing units of distance, and for magnetic variation given as east or west with a sign.
Worked example
Track 090 true, true airspeed 120 kt, wind 360 at 30 kt. The wind is a direct crosswind, so drift is about 14 degrees and groundspeed is about 116 kt. If the leg is 58 nm, time is about 30 minutes. With variation 5°E, the magnetic heading is about 090 minus 14 minus 5, so 071 magnetic.