True Course, Magnetic Course, Magnetic Heading, Compass Heading…Help!

This question comes from Josh:

I’ve had a little confusion with cross-country planning. It is with the magnetic and true courses. Can you tell me if this is right. When I plot the route and use my plotter, the course I get is a TRUE heading. I then add or subract the variation degree which converts it to MAGNETIC. Now, I need to put in the wind correction. The problem here is I do not know whether the wind I get from Flight Service is in magnetic or true. Could you please possibly explain this to me, sorry if my question sounds a little confusing.

Sure Josh, I’d be happy to help. I think the best way to help you is to define the terms we are dealing with a little better. I put these in the order that you would use when planning your cross country flight. We refer to this kind of navigation as dead reckoning. A lot of pilots don’t trust dead reckoning, but remember that dead reckoning is all that Charles Linbergh, Amelia Earhart and many other famous pilots had when planning some record breaking flights.

1) True Course (TC): This is the course measured from your navigation plotter when you plot your flight on your map. Remember that because of the projection of the map, it is best to read this course in the middle of the leg.

2) True Heading (TH): Now that you have a true course, we need to correct for winds which will give us a true heading. You can use a E6B or similar flight computer and forecast winds aloft to correct your true course to determine a true heading. To answer your other question, Forecast Winds and Temperature Aloft charts (FD) are given in reference to true north.

3) Magnetic Heading (MH): The difference between true north and magnetic north is known as variation. Lines of variation are shown on a sectional chart as dashed magenta lines and called isogonic lines. By adding or subtracting variation from your true heading you will get your magnetic heading.

4) Compass Heading (CH): Items from inside the airplane can actually affect the performance of the compass. Aircraft technicians take account for this and will place a placard beneath the compass displaying the errors for certain headings. These errors are referred to as deviation. By adding or subtracting deviation from your magnetic heading this will give you a compass heading. A compass heading is the direction you could turn the aircraft to that has been corrected for winds, variation and deviation. In an ideal world, this would have you following your true course perfectly that you had plotted earlier on the map.

So in review:

Course: Is always the line drawn on the chart

Heading: The direction which the airplane is pointed

Hopefully these definitions will help in the flight planning process. Most navigation logs have this laid out pretty well to help you keep the terms straight.

Thanks for the question Josh. Good luck with your training and cross country trips and…

Fly Safe!