Perhaps the most valid criticism of the scenario I have put forward, that they were approaching a position where closing range was critical, is that such an experienced crew would not have committed themselves to such without visual confirmation.
And of course they did not plan to do so as I hope I will be able to explain below, briefly.
From the various snippets that are known, this was a planned flight that Flt Lt Tapper had claimed his crew had trained for “intensively” (if that was the word I recall from memory just now). They were certainly familiar with the area.
I recommend readers acquaint themselves with the section in the Boeing (Mitchell) Analysis regarding the elevation profile on the final leg.
One of the possible profiles is that they were just about level along that leg right up to the final flare, albeit coasting (power levels found and slowing).
For argument's sake and for demonstrating graphically the situation, let's say they were at 700 ft.
Using Google Earth, you can lay down tracks (“paths”). To get a track corresponding to 035 mag at the time, draw you paths at 028 (near enough for this illustration) – use the ruler to give the line at an angle and then draw your paths over that line.
Do a long line through the position of waypoint change and another through the middle of that LZ (I have posted these coords previously). The line through the position of waypoint change is the track they actually took up to the last manouevre; the line through the middle of the LZ is the track I believe they thought they were on.
First, zoom in and out and tilt your perspective to get a feel for the two tracks;
then use the flight simulator tool on Google Earth thus: using the prop light A/C model, fly the two tracks at about 130 kts-ish and at about 700 ft.
See the difference?
Through the LZ, the slope is progressive and the ridge is just about their height – just a little pull back or an easy peel off to the left down the slope to the sea does it, if they had overshot the LZ or just failed to make it out clearly enough – the slope would have been such that the RADALT alarm would have been a sufficient warning. Regard the mist (which hugged the ground and was not that deep) and ground as a single surface and you can see that this would have been quite reasonable – just like approaching a sand or heath ridge at about the level of the top.
However, you should notice that on the track they took, not only is the ground ahead higher but presented a broad front with no easy exit left and had an abrupt cliff (that would have been hidden by the mist) which they impacted in the event.
You can check the realism of the topography against OS maps or Shuttle radar data – I suggest that for this illustration, Google is good enough.
So, if they had been on the track through the LZ they would have been OK for a wave-off.
Now, there is no way, with the best planning in the world, a sensible aviator would rely upon being that accurately on track without there being a local point reference on that track.
Had they been reliant upon a local reference that was supposed to have been on that LZ but was ½ mile or so up the slope, with their having planned a safe approach on the right track, how could they be negligent? So you don't have to be jeopardising the case for clearing their names by digging deeper into the activity planned at the Mull – nothing to lose.