Navigation
Navigation
Navigation tests dead reckoning, wind triangle, charts, magnetic variation, radio navigation and GNSS. The CPL candidate must plan a route and monitor position, fuel and time without relying on a single source.
Core rules
- True track is the intended path over the ground; heading is the direction the aircraft points. Wind causes drift, so heading = track ± wind correction angle. Magnetic heading = true heading ± variation; compass heading also includes deviation.
- The 1-in-60 rule: a 1 nm off-track error after 60 nm corresponds to about 1°. To close a 3 nm error after 30 nm, the correction is 3 ÷ 30 × 60 = 6°.
- VOR gives magnetic bearing from the station; NDB gives relative bearing to the station; DME gives slant range. GNSS gives position, track and ground speed, but RAIM and database validity must be checked.
- Charts show airspace, obstacles, minimum safe altitudes and reporting points. Position monitoring compares planned time, fuel and landmarks with actual progress.
Worked example
After 30 nm, the aircraft is 3 nm right of track. Using the 1-in-60 rule, the track error is 3/30 × 60 = 6°. To regain track over the next 30 nm, the pilot needs a further 6° correction, so the heading change is 12° left, or a standard closing angle of 12°.
Traps
- Applying variation in the wrong direction.
- Using compass heading as true heading.
- Trusting GNSS without checking RAIM or the database.
- Forgetting that DME range is slant range, not ground distance.