tech question

[apparent wanderer]

here's a technical question for you guys:
let's say you're tracking out from xyz vor, 240 miles out and find from atc that you're 4 miles left of course. what's your course correction to parallel the course? or to correct back to the course?
I understand that the 1 mile=1 degree at 60 miles rule is applied here, and that makes me think all you do to correct for a parallel course is come right 1 degree.
I realize this may be a simple problem to some out there, and that's good news to me. My aircraft (crj) has a nice picture of the airway, so all I do is say "look, we're left of course, let's aim right until we're back on the pretty white line"
but honestly, the fms doesn't really get off course anyway. kinda nice.
got the final at the end of this month and this is one question that is eating at me.

[Hugh Gorgen]

AW,

I agree with 1 deg right.

1 deg at 60 nm = 1 nm. Therefore 4 degrees at 60nm = 4 nm.
0.25 deg at 240nm = 1nm . Therefore 1 deg at 240nm = 4 nm.

Good luck with interview.

[WaldoPepper]

Just to add a bit more...

If you wanted to parallel track, what you've said above is correct. If you want to regain track at the next waypoint you need to add the Track Error (TE) to the Closing Angle (CA).

eg: 4nm off track after 240 nm and the next waypoint is 120nm ahead of the calculation point. A simple 1:60 works again using the above formula.

HDG Correction = TE + CA

Therefore:
4nm off track after travelling 240nm = 1 deg (TE)
4nm off track with 120nm to go = 2 deg (CA)

Therefore, correction to your HDG would need to be 3 deg to regain track at the next waypoint. If you want to regain before the waypoint, just need to work out the distance to run to that point.

You can see how this works if you draw a rough diagram. Using simple trigonometry (equal angles) you can visualise whats going on.

Next thing is to try and hold your HDG so it works!

WP

[apparent wanderer]

Thanks, guys. I feel better about it now. Most other questions I've seen I have been able to come up with an answer, or research one. This just isn't one of the things stressed in U.S. aviation, I guess. All my books just say "turn right to a heading that will bring the needle back." I fear an interviewer at CX might not find that amusing by any means.
A week to go for the final and I'm just wrapping things up...
aw