What is your on-course heading?

This is a question about a question!

Pilot Mike writes:

Thought I’d throw this one over your way to see what your thoughts are. Hangar flying this question has yielded several different answers from both IR pilots and CFIIs… You are departing an airport on an IFR flight plan; the route is “direct” to your destination. Upon climb out, ATC gives you radar vectors around arriving traffic at another airport. After about 15 minutes away from your filed route, ATC asks, “What is your on course heading?” Which heading do you provide back to ATC? Some different answers I’ve been told: 1. The heading direct to your destination from your present position 2. Heweeading to intercept your original filed route. 3. The original on course heading as filed. What is the appropriate response to ATC?

The appropriate response to give ATC is your heading that you would need to fly from your present location to the fix as specified in ATC’s request.  Why would controller need this information?  Well, I forwarded this question to Paul from FAAfolies.com and here was his response:

There are a variety of reasons the controller might need to know the heading; you’d think it doesn’t matter since the a/c has direct nav capability but it might be to see what the winds are, or there might be traffic to parallel, or other reasons.

I also called my local approach control facility and their answer was that many times the destination or next fix is defined to ATC in terms of lat/long coordinates.  You can only imagine how difficult it would be for a controller to know the on-course heading difference to a place that is 39N 34 55 versus 40N 05 10.

So what I do when ATC asks me? Well, to be honest, I just normally look at my GPS or FMS PFD and find the BRG or DTK field:

Colin ProLine DTK Field

The course in that field, is the number I usually respond to ATC with.  Any technically it isn’t a “heading” and it doesn’t help ATC know what the winds aloft are but I haven’t gotten any complaints yet.  Again, the feeling I got from ATC was that they are just looking for a general idea of which way your going to turn to proceed to that fix.  If they need left or right of that course for traffic sepeartion, they are going to tell you to turn.

Thanks for your question Mike and….

Fly Safe.