Navigation
The navigation toolkit
Controllers must understand how aircraft navigate to anticipate their positions. Know the earth's coordinate system: latitude, longitude, great circle and rhumb line tracks. Understand magnetic versus true north and the meaning of variation and deviation. Know the VOR, DME, NDB, ILS and GNSS systems at a conceptual level, and how aircraft use them to fix position. Understand RNAV and RNP and the difference: RNP includes on-board performance monitoring and alerting.
Flight planning and tracks
Know how track, heading, course and bearing differ. Understand wind triangle concepts: heading, track, drift and groundspeed. Know the transition altitude/level and how altimeter settings change with navigation. Be clear on waypoints, airways, and ATS routes.
Traps and a rule of thumb
Traps: confusing heading (where the nose points) with track (the path over the ground); forgetting magnetic variation; and treating RNAV and RNP as identical. Rule of thumb: heading + wind = track; track is what the controller sees on radar. Worked example: an aircraft tracking 090° with a wind from the north will have a heading slightly north of 090° to maintain the track - the controller should expect the aircraft to crab.