Dead reckoning
Known heading and speed plus elapsed time gives a predicted position. Wind shifts that prediction, so pilots solve a wind triangle to find the heading needed to hold a desired track and the resulting ground speed.
Magnetic reality
Charts show true north; compasses point to magnetic north. Variation converts between them and deviation corrects for aircraft magnetic fields. Most modern systems handle this automatically, but the concepts remain in every chart legend.
RNAV
Area navigation lets an aircraft fly directly between waypoints defined by coordinates rather than following ground beacons. Performance-based navigation specifications such as RNP 1 state the accuracy the aircraft must hold 95% of the time.
Key points
- Ground speed = true airspeed corrected for wind component.
- True heading = magnetic heading corrected for variation.
- RNP defines required accuracy, not the equipment used to achieve it.
Knowledge check