ADF outbound - needle always swings towards the tail?
I was in the SIM today with my instructor, finishing some IF time for my CPL, when he mentioned that no matter what, the ADF needle always swings towards the tail the further outbound you are.
Now I know my Pythagoras, so the only way the ADF needle would move further towards the tail the further out you got is if you were the same distance off track the entire way (same as the 1-in-60 rule).
For example, if you are tracking 090 and laying off 10 degrees of drift on a heading of 100, then unless the wind changes or you steer off track, the angle between your heading and the NDB will remain the same the entire way - 10 degrees (right) off the tail. It doesn't slowly starting moving left as you get further out . . .
If you move off track, however, the deflection will obviously be larger the closer you are to the aid, and lessen as you move away from it.
My instructor said this was true in theory, but not in practice: even if you are 100% on track and maintain the same heading to offset the same wind (as in my example above), the needle will still slowly centre itself towards the tail.
I can't see how this is possible, and haven't been able to find any reference. The only thing I can think of is that, practically speaking, you are never going to be exactly on track, and so yes: the further out from the NDB you are, the less needle deflection will be for any given track error (one degree for every mile off track for every 60 miles outbound).
Am I missing something? He says pilots learn this when they do their IFR.