Navigation, Flight Planning, and Cross-Country Physiology
From true course to compass heading
The navigation sequence is mechanical: plot a true course, apply variation to get magnetic course, apply deviation to get compass heading, then apply wind to convert TAS into groundspeed and true heading. Mnemonic: east is least, west is best - with easterly variation magnetic is less than true.
Flight planning questions test fuel and time arithmetic and the regulatory reserve: 14 CFR 91.151 requires 30 minutes of fuel beyond the destination for day VFR and 45 minutes at night. Compute leg time from groundspeed, not true airspeed.
Cross-country flying is physically demanding. Long legs at altitude invite hypoxia (especially above 10,000 ft MSL in an unpressurized cabin), dehydration from dry cabin air, fatigue, and carbon monoxide exposure from the heater. Middle-ear and sinus blocks on descent are handled with Valsalva or Toynbee and slow descent rates. Fatigue degrades judgment before it degrades skill.
Trap: mixing up variation and deviation, or failing to apply wind before computing time.
Worked example: True course 360°, variation 12°W, deviation 4°W. West is best → magnetic = 012°, compass = 016°. With a 20-knot headwind and 120 KTAS the groundspeed is 100 knots, so a 150 NM leg takes 1.5 hours.