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There are a number of threads and posts here about the difference between stock localizer heading and the associated runway heading. I have just come across this while adding ILS support to ADE. I have confirmed with Asobo that the runway heading is true (as it always has been) but the localizer heading is now magnetic. Previously it was true. It's not clear why this change was made.
What I know about air navigation and ILS approaches can be written on the head of a pin. I do know that one flies at an angle to the runway to acquire the localizer and then follow it to the runway. I assume therefore that generally the localizer needs to align with the runway. An extreme example of a large magvar is YSSY (-13) so that rwy 07 has a true heading of ~74.079 while the localizer has a heading of ~ 61.079. Flying on ~61.079 does not align the aircraft with the runway unless the instrumentation is adjusted to allow for the magvar?
So how does this get handled? Do we change the localizer heading in the airport data to take account of the magvar. I think there are some ILS not aligned with the runway though.
I would like to get a definitive approach to handling localizer data so that it works correctly for ILS approaches.
All advice and suggestions much appreciated
What I know about air navigation and ILS approaches can be written on the head of a pin. I do know that one flies at an angle to the runway to acquire the localizer and then follow it to the runway. I assume therefore that generally the localizer needs to align with the runway. An extreme example of a large magvar is YSSY (-13) so that rwy 07 has a true heading of ~74.079 while the localizer has a heading of ~ 61.079. Flying on ~61.079 does not align the aircraft with the runway unless the instrumentation is adjusted to allow for the magvar?
So how does this get handled? Do we change the localizer heading in the airport data to take account of the magvar. I think there are some ILS not aligned with the runway though.
I would like to get a definitive approach to handling localizer data so that it works correctly for ILS approaches.
All advice and suggestions much appreciated