Peter wrote:
I recall rumours from France that there are IAPs where you self-announce. No idea if that’s actually the whole story. It would work, obviously, but is emotionally a very hard thing for the regulators to swallow.
At Swedish airports with AFIS, you self-announce through the whole procedure unless there happens to be a control area with a suitably low base overhead. It is perhaps not the whole story, since the AFIS unit will keep track of flights, tell new arrivals what’s going on and can “suggest” that you enter a hold etc. But in the end the pilots are responsible to provide sequencing for themselves.
tomjnx wrote:
The GPS doesn’t work like that,
Well, ADFs and ILS localisers don’t work like that either, but magnetic tracks are still published. If you ask a GPS navigator to provide guidance from point A to B, it will give you the direction from A to B as a magnetic track.
Magnetic tracks are given for pilots to fly by. What techniques the navigation equipment uses to determine track and course deviation is a different matter altogether.
Tom makes a lot of sense. Also the variation is printed on charts per yr as in such and such amount.
Flyer59 wrote:
The final course of an airport is given in degrees magnetic, no? Final course is a “Magnetic Course”.
Yeah that’s for the convenience of the pilot looking at legacy instruments, such as the infamous spirits compass.
The GPS doesn’t work like that, it uses a (recoded version) of the final approach segment data block. As you can see, there’s no magnetic variation involved in the fields. Some countries even print the FAS DB in hexadecimal in their AIPs – a practice whose purpose somewhat escapes me.
If magnetic north wanders and the runway numbers no longer corresponds to the runway alignment, what do you do? Most people would not rotate the runway, but repaint the numbers. So no need to change the FAS DB, since location and alignment in space remains the same.
I was being serious. There should be many more thread starts. A lot of people complain to me about threads going off topic.
But starting threads is not my job. Anybody can do it 
I think we have beaten this IFR approach/departue to death so Peter I agree with you.
I will give my most vociferous antagonist the last word.
Why not start a thread on why do GPS approaches need calibration slights?
I have to agree with Stephan. As far as GPS is concerned it is an absolute point on earth that does not change over time. Perhaps geologic time with plate tectonics.
However Im sure that they check GPS approaches for locally induced errors to the signal. At least that what Im thinking/guessing. How often who knows maybe its a calendar date as opposed to # of complaints filed with the airport or ATC.
Anyone know for sure?
Can the magnetic variation only be calibrated through a calibration flight?
That seems like a very expensive way of determining the variation for a GNSS approach.
But the approach chart, Stephan, it gives magnetic courses between those points, and a Final Course in Magnetic Degrees
