General Navigation
General navigation questions test map reading, the Earth's geometry and the triangle of velocities. Understand latitude and longitude, great circles and rhumb lines, and the properties of the main projections (Mercator, Lambert conformal conic, polar stereographic). Know that a Mercator chart shows a rhumb line as a straight line, while a great circle is curved.
Learn to compute track, heading, drift and ground speed from TAS and wind. Be comfortable with the 1-in-60 rule: a 1 NM offset at 60 NM is about 1°. Use it for drift and for correcting back to track.
Understand magnetic variation and deviation, and the order of applying them: true to magnetic to compass. Know the meaning of isogonal and agonic lines.
Traps: applying variation in the wrong direction; confusing track with heading; and forgetting that chart convergence affects grid headings.
Worked example: TAS 120 kt, wind 240/30, required track 090. The wind is from the right, so drift is to the left; compute the wind component and apply the 1-in-60 rule to estimate drift, then correct heading into wind.
Rule of thumb: to correct a known offset, use track error × distance to go / 60 to find the correction angle.