Walter
What could put this argument to bed – or develop it – would be if someone retraced the approach in a light aircraft equipped with DME and found out for sure.
Love to, but I don't think it would prove anything, for several reasons:
1. At the time of the accident the MAZ TACAN was operational. Now it's a civil DME, albeit on the same frequency but for sure it will have different operating parameters such as power levels etc
2. You can't assume that a DME receiver in a particular light aircraft will perform in a similar way to the equipment in ZD576. On the whole I'd expect the light a/c to have worse reception but the point is you just couldn't possibly make any assumptions.
3. It's not known exactly what height ZD576 was flying at when the supposed DME signal was received. Even a 50ft height change could make the difference between receiving and not receiving the DME signal
4. The old TACAN and the current DME are in significantly different locations - the TACAN was 2nm west of where the VOR/DME is now. Again, if anything one would expect that to mean the DME is less receivable from low level off the Mull of Kintyre than the TACAN was, but you just can't make assumptions.
I do think, though, that the Boeing study raises one of the key questions of the ZD576 mystery, and that is, why did they make that heading correction to the right?
and annuvver fing:
We were standing part way up the slope between the lighthouse and the crash site at a point where below us we could see the sea/lighthouse but around us and above there was thick mist. A helicopter came in very close and turned very near us – we could feel it but we could not see it. “They do that all the time” he said; “They turn over that big rock” he said pointing to a prominent feature right on the shoreline.
Just because you're in fog on the ground doesn't mean your unseen helicopter pilot can't see anything. The key is in what the keeper told you - "they turn over that big rock". As far as I'm aware there ain't no navaid on that rock. So how do they know to turn over it? Because they can SEE it.