How do I interpret ATC-directed headings?
Mike has a great question, one that is often brought up at the start of instrument training:
When given a heading by ATC, is it magnetic, true, or something else?
Whenever you are working with an air traffic control facility, any radar vectors they give you will be turns to magnetic headings only. This simplifies things, both on the ground and in the air, and means you don’t have to do math in the cockpit. It would be especially challenging over long distances, particularly east-west, as magnetic variation can change quite a bit. The only time you’ll typically encounter any kind of true headings will be during the planning phase of your flight.
Your question brings up another area of confusion that I see fairly often, especially in glass cockpits or in aircraft with GPS that provides ground track information: only use your ground track when you’re doing some kind of radio navigation! I can’t count the number of times we’ve gotten a vector and my student follows up by asking if we should fly a ground track of 340°.
So remember, if you get a vector, fly the magnetic heading. And don’t forget to update your heading indicator to your compass every 10 minutes or so!
Footnote: Blake makes a great point in the comments. Canada’s Northern Domestic Airspace, which includes the North Pole, contains such high amounts of deviation that all headings and tracks are requested in True, rather than the highly inaccurate Magnetic. Thanks, Blake!