The “heading” is the direction the aircraft is headed in relative to magnetic north (not true north). The compass aligns with the earth’s magnetic field.
Headings are expressed in “degrees” clockwise from magnetic north where a circle is 360 degrees.
North is 0 degrees, commonly referred to as 360 degrees.
East is 90 degrees.
South is 180 degrees
West is 270 degrees.
When expressing a heading, you will pronounce all three numbers adding in a zero in front for any one or two digit numbers. For example: (005) zero zero 5 degrees or (010) zero one zero, or (215) two one five.
Non Electronic Flight Display
For aircraft non-electric flight displays, the display will usually have a heading indicator which is gyroscopically stabilized to avoid errors in the magnetic compass due to turning or accelerating/decelerating.
Matching the heading indicator to the compass
Start by reading the current heading in the compass under the lubber line while steady and not turning, accelerating or decelerating. Then set the heading indicator to that setting by pushing in the adjustment knob and rotating the compass card to the appropriate heading. Over time, the heading indicator will need to be adjusted to account for errors, so make adjustments about every 15 minutes.
Electronic Flight Display
The electronic flight display will show the current heading in relation to magnetic north. which is stabilized to avoid errors. The heading information comes from a remote magnetometer.
Electronic and Non Electronic flight displays are equipped with a “heading bug” which can be set to the desired setting by turning the HDG knob (or knob on the instrument cluster).
This can also be set to the runway heading before takeoff to ensure you ar eon the proper runway or to the direction the local winds are from during taxi as a reminder for aileron and elevator corrections needed to compensate for the wind during taxi.
Magnetic Compass should be checked every flight for proper fluid and level and is required to be inspected every 12 months as part of the annual inspection.