Basics of Navigation

3. Bearings in Degrees

When quoting a course in degrees, it is assumed that the full circle corresponds to 360 degrees, as is usual with a protractor.  North is therefore  both 000 (zero) and 360 degrees.  South is always at 180 degrees.  The east corresponds to 90 degrees and the west to 270 degrees.  These bearings function like cardinal points and are unique and identical to compass data like south or southwest.  

But, degrees can also be used in relation to one's own position and flight direction.  A change of course BY 10 degrees is slightly different from a change of course to 10 degrees.  Therefore, in aviation, course information is always given as a new heading (given by 3 separate digits) and never as an angle of change.  

E.G. "Fly heading Three Two Zero"