The fundamentals of visual navigation include two main methods as discussed in Monday’s post, pilotage and dead reckoning, each of which should be used in conjunction with the other. Whether flying by means of visual navigation or even by reference to instruments like a VOR it is possible to find yourself in an off-course situation. Remember atmospheric conditions change and the winds you use for your flight plan are only forecasted and not exact.
Considering the theory explained in Monday’s post on the wind triangle (vector analysis), let’s discuss a quick and easy way to get back on course using what’s called the off-course correction equation.
I like to think of the above equation as a two part problem. The first part Distance Off x 60 / Distance Flown will give you a degree of heading change to parallel your intended course. Part two Distance Off x 60 / Distance Remaining will give you an added heading change degree to converge on your course at whatever distance remaining you enter into the equation. By adding part one and two together you get your Degrees of Total Correction. This is the degree of heading change you will need to converge back on course at whatever distance remaining you enter. So for example, if you enter a distance remaining of 50 miles you will converge back on your intended course at the 50 mile mark. Let’s work through a problem together.
Problem:
Off Course = 4 miles
Distance Flown = 40 miles
Distance Remaining = 80 miles
Step 1: Take our distance off course of 4 miles and multiply by 60 (4 x 60 = 240).
Step 2: Divide 240 from step one by distance flown of 40 miles (240 / 40 = 6°).
So at this point a 6° heading change would allow us to parallel our intended course. To find the distance to converge back on course we will need to complete the second part of the problem.
Step 3: Take our distance off course of 4 miles and multiply by 60 (4 x 60 = 240).
Step 4: Divide 240 from step one by distance remaining of 80 miles (240 / 80 = 3°).
Our total heading correction to converge would be 6° + 3° = 9°.
Some additional tips and tricks: by properly using a navigation log associated with my flight plan, I will have known approximately how far I have flown and my distance remaining to either my destination or next check point. You may also use an E6-B or CX-2 Flight Computer to determine off-course corrections.
Try one on your own.
Off Course = 2 miles
Distance Flown = 15 miles
Distance Remaining = 22 miles
(Answer posted in the comments section)
