It’s confusing because they are often (incorrectly) used interchangeably in conversation: Heading, bearing, course, and track. Even correctly used by ATC, “on course heading” is still a little misleading because below you’ll see they’re practically referring to “course” and not “heading”. So what is the difference between heading, bearing, course, and track anyways?
Heading is the direction the airplane is pointed, whereas track is the actual direction of the airplane tracking across the ground. Bearing is the angle between any two points, whereas course is your intended path of travel to your destination.
In the rest of this post we’ll elaborate on each of these points and then also provide a real-world example that incorporates the accurate use of all of these terms.
Heading
Heading is probably the most confusing term out of all of these because it can most easily be used in conversation to replace track, bearing, or course. By definition though, heading is actually just the direction that the nose is pointed. This does not factor for wind, or the actual movement of the airplane across the ground. It only refers to what the compass reads based on where the nose is pointed.
So you can be “heading” due north but if you have an incredible wind from the west, you might still be pointed (heading) due north but actually tracking over the ground to the northeast. Magnetic variation and deviation of the compass also impacts what heading you’ll need to be pointed to maintain a given track. Speaking of track, let’s cover that next.
Track
Track is the easiest of these four to understand in my mind, because it simply refers to how you are actually tracking over the ground. When navigating in the air, your track is really all that matters in terms of getting to where you want to go. If you need to go northeast to your destination, and have a significant wind from the west, your heading might be to the north in order to achieve a track to the northeast.
For example, my Garmin 430 GPS will present my current track as well as the desired track to get to a particular destination. This is the track over the ground I need to achieve to get to where I’m going. If the track and desired track don’t match, then I have a heading problem. Luckily if you have an autopilot that is coupled to your GPS, if you hit “nav” mode then it is going to solve for the correct heading to fly your desired track.
Heading and track are really the two main categories of direction of flight, but they are further broken down into bearing and course which we will cover next.
Bearing
Bearing can be confusing sometimes because has some overlap with course. Bearing is simply the angle or direction between two points. A practical application of this is in VOR navigation. It’s a common thing to hear someone say “we are bearing 090 from the station”. This simply means that off of the VOR they are tracking on the 090 radial outbound from the station. In relation to the VOR they are bearing 090.
Due to wind correction angles you might have to be heading something different than 090 in order to track 090. If you have a northerly wind, you might have to head 080 in order to track along the 090 bearing off of the VOR.
Along the way though you might triangulate your position from another VOR by determining what the bearing to that station would be. You could be on the 180 radial for one VOR and the 090 radial of another one, and those are two separate bearings from the station. Bearing has less to do with your desired course as it does with describing where something is in relation to something else.
Course
Course is very similar to bearing in that it’s the desired direction for your route of flight. If you are going directly from one airport to the other, your course and bearing will be the same along the route of flight. If you are flying from an airport to a VOR to another airport, your course will change in each leg, as will your bearing.
Example
For this example we’re going to work backwards through the above mentioned directions. Assume you are departing an airport and your destination is directly eastbound. When you take off the course between the departing airport and destination airport is 090. In this instance the bearing of the destination airport off of your departing airport is also 090. This is also the direction you want to track the airplane so that it will stay on a course of 090.
Your (compass) heading may or may not be 090, depending on both the wind correction angle (which you can solve for using an analog or digital e6-b calculator), magnetic variation of your location, and any deviation of the compass itself onboard your aircraft. Remember the following calculation to solve for your compass heading in order to fly your desired track or course (both 090).
True (Desired) Course +/- Wind Correction Angle = True Heading
True Heading +/- Magnetic Variation = Magnetic Heading
Magnetic Heading +/- Deviation = Compass Heading
From the above calculation, you can determine what your actual heading on your compass will need to be to maintain your desired course to get to the destination airport.
Does a GPS Use True or Magnetic Heading?
The above example assumes you are using the compass in your airplane (hence why it requires so many steps to calibrate the difference between your true course all the way down to your actual compass heading). But what about a GPS? By definition it’s not using earth’s magnetic fields as a way of navigation, but rather positioning information provided by satellites. So if it shows your “desired track” is that a true or magnetic heading?
I did some research and AIM (Aeronautical Information Manual) 1-1-19 addresses this in section L:
“There may be slight differences between the course information portrayed on navigational charts and a GPS navigation display when flying authorized GPS instrument procedures or along an airway. All magnetic tracks defined by any conventional navigation aids are determined by the application of the station magnetic variation.
In contrast, GPS RNAV systems may use an algorithm, which applies the local magnetic variation and may produce small differences in the displayed course. However, both methods of navigation should produce the same desired ground track when using approved, IFR navigation system. Should significant differences between the approach chart and the GPS avionics’ application of the navigation database arise, the published approach chart, supplemented by NOTAMs, holds precedence.
Due to the GPS avionics’ computation of great circle courses, and the variations in magnetic variation, the bearing to the next waypoint and the course from the last waypoint (if available) may not be exactly 180° apart when long distances are involved. Variations in distances will occur since GPS distance-to-waypoint values are along-track distances (ATD) computed to the next waypoint and the DME values published on underlying procedures are slant-range distances measured to the station. This difference increases with aircraft altitude and proximity to the NAVAID.”
