Navigation and Flight Planning
Three ways to know where you are
Pilotage uses ground references, dead reckoning uses heading, time, and wind, and radio navigation adds VOR, GPS, and WAAS. A VOR radial is a line extending FROM the station, so the CDI centers with a TO/FROM flag that tells you which side you are on. GPS integrity depends on RAIM, and WAAS and RAIM prediction matter for approaches.
The wind triangle
Work through headings in a fixed order: true course, then apply variation to get magnetic course, then deviation to get magnetic heading, then wind correction angle to get the heading to fly. For converting true to magnetic, remember that east is least and west is best: subtract easterly variation, add westerly.
Traps
- Variation is the earth's magnetic field, charted on the sectional; deviation is compass error in that airframe, recorded on the compass correction card.
- Magnetic compass errors: on east/west headings, acceleration causes a turn toward north in the Northern Hemisphere; on northerly headings the compass lags in a turn, and on southerly headings it leads.
- Lost procedures follow the five C's: climb, conserve, communicate, confess, comply.
Worked example
True course 090, variation 12 E, deviation 2 E on the correction card. Magnetic course = 090 minus 12 = 078. Compass heading = 078 minus 2 = 076. Fly 076 and hold the wind correction angle computed from the wind triangle.