The so-called one-in-sixty rule is a very useful and agile approximation to solve practical problems regarding both lateral and vertical air navigation.

The most obvious advantage of this rule is the avoidance of trigonometric functions rendering the calculations a matter of simple arithmetic procedures.

The rule: if an aircraft has travelled sixty miles with a track error of one mile, then the corresponding drift angle equals approximately one degree (1°). Proportionality applies.

This rule-of-thumb is often used for:

♦ the conversion between drift angles and drift lengths; e.g. to correct lateral deviations from cross-track drifts (L-NAV)

♦ the estimation of arc lengths (L-NAV)

♦ the estimation of a descent profile (V-NAV)

The mobile application allows you to practice the one-in-sixty rule-of-thumb. It also allows you to explore its accuracy. Have fun!