Howdy!
I have a question in regards to the answer for this question.
Initial distance off track to calculate TE is 5nm but the distance travelled is still only 30nm.
Could you please run by me why we add on the bottom off track?

Its probably staring me in the face!

Hi there,

If it's a 1 in 60 related question the way to would out track error in this case would be, "if I'm 5nm off track after 30nm, how far off track would I be after 60nm?" Answer being 10nm, therefore 10 degrees of track error.

You need to know how far you've already gone to get the track error, then you need the remaining distance to apply that track error + closing angle.

Hope I've understood your question, let me know if I haven't!

Cheers

This is a cross-track one in sixty problem.

To find the track error, you must consider the total cross-track distance flown between the two fixes. Your first fix was 3nm left of track and the second fix was 2nm right of track. So the total cross-track distance flown is 5nm over a total distance of 30nm between the fixes. That's 5nm after 30nm flown so the track error is 10 degrees.

However, if you change your heading by 10 degrees to the left at the second fix, you will simply parallel the flight planned track and you will not close in to the destination [X]. You need a further correction to actually close in to the destination. To find that extra closing angle, you consider the distance off track at the second fix [2nm], and the distance to go to the destination [30nm]. That's another 4 degrees. So to close in to the destination, you must change the original heading by 10 + 4 = 14 degrees to the left.

Bob

Thanks Bob and Ellzy!
Passed the exam this morning!

This is the only ATC book I've used and to be honest, I really appreciate the clarity of your style Bob, much more interactive than just reading, the font is bigger, plenty of original diagrams!

On to my second last exam, Law!