1) Ship heading 
A bearing as indicated by the horizontal angle between the compass needle and the centerline of the aircraft. A Compass Course is equal to a True Course 
The angle between the: longitudinal axis of an aeroplane and the compass needle, measured clockwise from the compass needle between 0 degrees and 360 degrees.
a course whose bearing is relative to the meridian as given by the navigator's compass, no compensation being made for variation or deviation. Cf. true course, magnetic course.