Navigation (General, Radio, Instrument)
What the exam tests
This domain tests chart work, the triangle of velocities, heading and track conversions, and basic radio navigation using VOR, DME, NDB, ILS and GNSS.
Core rules
- Track is the path over the ground; heading is where the nose points. Wind causes drift, and the wind correction angle is applied to the track to obtain heading.
- True heading plus or minus variation gives magnetic heading. Magnetic heading plus or minus deviation gives compass heading. East variation or deviation is subtracted when converting from true to magnetic or magnetic to compass; west is added.
- Time, speed and distance use the relationship distance equals groundspeed multiplied by time. Fuel required equals fuel flow multiplied by time, plus reserve.
- A VOR gives a magnetic radial from the station; DME gives slant range, which is greater than ground distance when close in and high. NDB/ADF gives a relative bearing. ILS gives lateral and vertical guidance.
- GNSS position accuracy depends on satellite geometry, RAIM and signal integrity.
Worked example
True course 090°, variation 5°E, deviation 2°W. True to magnetic: subtract east variation, giving 085°M. Magnetic to compass: add west deviation, giving 087°C. The pilot flies 087° compass to make good 090° true in still air.
Traps
Applying variation to a magnetic heading in the wrong direction; confusing track with heading; treating DME as ground distance; and using GNSS without checking RAIM when required.