The 1 in 60 Rule states that for every 60 NM (Nautical Miles) distance flown, being 1 NM off-track results in being 1 degree off-track, and vice versa.|
Opening and Closing Angles
The Opening Angle (θo), represents the Track Error, and the Closing Angle (θc) the difference between the required corrected track (to the new fix) and the original track to that same fix.
Double Track-Error Method
If the position fix (indicating that we are off-track) occurs before the half-way point of the leg, we can apply the Double Track-Error Method. That is, we apply Double the Track-Error as our Track/Course correction for as many minutes as we have been flying off-track (i.e. from te start of the leg). This method, however, does not work if we have passed the mid-way point between the points on either end of the leg. In such cases, we can apply the Opening and Closing Angle Method.
Opening and Closing Angle Method
Addition of the Opening Angle (θo, Track Error) and the Closing Angle (θc, angular difference to end of leg fix) gives us the Correction Angle we need to apply to our Track/Course.
The Standard Closing Angle Method
In the Standard Closing Angle method, for every Ground Speed (GS, the equation uses NM/min), there is a Standard CA (Closing Angle), listed below, which is flown for as many minutes as we have flown off-track. Whilst this method is typically used for high-speed, low-flying aircraft, it can also be used for slower Ground Speeds. The table below shows the Standard Closing Angles for a variety of Ground Speeds:
|Knots||NM/min||Closing Angle (°)|