Navigation: General, IFR Navigation and Flight Management
This domain ties together the navigation theory and the practical flight management that an IFR helicopter pilot needs. Candidates must understand the earth's coordinate system, chart projections, track and heading, wind triangle, and the use of area navigation and flight management systems.
Concepts to master
- The wind triangle: true track, true heading, wind direction and speed, and the drift angle; the conversion between true and magnetic.
- Chart projections: Mercator (rhumb line and great circle) and the scale variation with latitude.
- Area navigation: RNAV and RNP, the meaning of the required navigation performance, and the containment region.
- Flight management: waypoint sequencing, the difference between track-to-a-waypoint and a fixed route, and the effect of wind on the ETA.
- The 1-in-60 rule: a 1 degree error over 60 NM is 1 NM off track.
Common traps
Questions mix true and magnetic, or ask for the heading when the track and wind are given. Another trap is assuming an RNAV route removes the need to monitor the raw data.
Rule of thumb
The 1-in-60 rule: distance off track = (track error in degrees x distance flown) / 60.
Worked example
You are 10 NM off track after 120 NM. The track error is (10 x 60) / 120 = 5 degrees. To converge, double the closing angle: turn 10 degrees toward track and you will regain it in the same distance again.