If a pilot is flying a leg of 120 miles and finds after traveling 60 miles that he is two miles to the right of track, then a correction of 4° to the left (2° to fly parallel to the intended track and another 2° to bring him to his target) will bring him to his destination. If a pilot is flying a 120-mile leg and finds after 30 miles that he is two miles left of track, then he has flown 4° left of his intended track, i.e. :2 × 60/30 left of track. Changing the heading four degrees right will now bring him to parallel the intended track. At that point he still has 90 miles to his next waypoint. He is thus two miles to the left of that and thus the waypoint is 4/3 of a degree (2 × 60/90) to the right, or approximately 1° right. The pilot then adds these two to get 5° and flies 5° right of his previous heading. One can also use the 1 in 60 rule to approximate distance from a
VOR, by flying 90 degrees to a radial and timing how long it takes to fly 10 degrees (the limit of the
course deviation indicator). The time in seconds divided by 10 is roughly equal to the time in minutes from the station, at the current
ground speed. ==References==