Navigation - Triangle of Velocities and In-Flight Techniques
The navigation triangle
Every navigation problem reduces to three vectors: heading and true airspeed, wind direction and speed, and track and groundspeed. Draw the triangle, then solve for the missing element. Convert true to magnetic by applying variation (east is least, west is best: true to magnetic, subtract easterly variation) and magnetic to compass by applying deviation from the card. Track is the path over the ground, heading is where the nose points, and the difference is the drift or wind correction angle.
In flight
Use dead reckoning with visual fixes, and know the radio aids well enough to identify, tune and interpret them: VOR radials, NDB bearings and GNSS, including its limitations such as jamming and RAIM. Work in UTC for all planning. Check fuel and groundspeed at every waypoint, not only at the destination.
The 1-in-60 rule
A track error of 1° places you 1 NM off track after 60 NM. The relationship scales linearly, which makes drift and closing-angle corrections quick mental arithmetic.
Common traps
Applying variation in the wrong direction; confusing variation with deviation; forgetting that groundspeed varies with wind; and planning in local time.
Worked example
After 40 NM on a planned track of 090° you find yourself 2 NM to the right. Track error = 2/40 × 60 = 3°. Twenty nautical miles remain, so the closing angle = 2/20 × 60 = 6°. Turn left 3 + 6 = 9° to a heading of 081° magnetic and you will converge on destination.