Measuring true track on a chart
True track is the angle of the A-to-B line, measured clockwise from true north with a protractor.
- Measure the angle where the line crosses a meridian (a line of longitude, running true north-south): that gives true track (TP 1102). Apply variation to get magnetic track: West adds, East subtracts (memory aid "east least, west best", not in the CARs/TC AIM).
- By component, true track =
atan2(east, north): the bearing turns clockwise from north (000°), through east (090°), south (180°), west (270°). - The reciprocal (outbound ± 180°) is the track from B back to A (TP 1102).
Trap: taking the reciprocal track, swapping the north/east offsets, or reporting true track when magnetic was asked (or applying variation the wrong way, which doubles the error).
References
- TP 1102 (measure true direction against lines of longitude, then apply variation; reciprocal = outbound ±180°)
- TC AIM MAP 2.5 (VFR charts)