6.36 The 1 in 60 Rule

6.36.2 1:60 rule computations.

The 1 in 60 rule is a simple method used in visual navigation to estimate track error and calculate the correction required to regain the planned track.

The rule is based on the approximation that:

1 nm off track after travelling 60 nm represents a track error of approximately 1°.

Therefore:

• 1 nm off after 60 nm = 1°
• 5 nm off after 60 nm = 5°
• 10 nm off after 60 nm = 10°
• 15 nm off after 60 nm = 15°

It is not necessary to travel 60 nm before using the rule. The same relationship can be applied proportionally to any suitable distance.

For example, being 1 nm off track after 30 nm is equivalent to being 2 nm off track after 60 nm, giving a track error of approximately 2°.

Track Error (TE).

Track Error (TE) is the angle between the required track (TR) and the track made good (TMG).

To calculate track error:

TE = (60 × Distance Off Track) ÷ Distance Gone

Where:

• Distance Off Track is the perpendicular distance between the aircraft's position and the required track.
• Distance Gone is the distance travelled along the required track from the last known on-track position.

Example

An aircraft has travelled 30 nm and is 2 nm left of track.