ampan:
Welcome to the debate. It is nice to see someone advancing logical arguments with some facts to support their conclusions .
You say (#223)
As to the crew's certainty of their position, there is one piece of evidence that is never referred to. Just before the Ground Proximity Warning System sounded, the captain said "We're 26 miles north. We'll have to climb out of this." The first officer, seated in the right-hand seat, says "It's clear to the right and ahead. You're clear to turn right. There's no high ground if you do a 180." The captain responds "No. Negative." At this point, the GPWS sounds, the captain calls for go-around power and there is a sudden manual application of LEFT rudder.
No-one, including Mahon (who never referred to this evidence), has explained why a pilot who is certain he is in the centre of McMurdo Sound would decide to turn left to climb out, because Erebus and Mount Bird would be to the left. The obvious manoeuvre was the right turn that had been expressly suggested by the first officer. The first officer, of course, was wrong. A right turn would have produced a collision with the cloud-covered Mount Bird - and the captain, in the final seconds of the flight, appeared to have some appreciation of there being danger to the right. And when the GPWS sounds, there is an immediate attempt to climb out, rather than any reference the possibility of a false alarm. None of this is consistent with the crew being certain that they were in McMurdo Sound.
Justice Mahon picked up on this inconsistency, and although he never put it in his report for some very good reasons, he later explains what really happened in his book
“Verdict on Erebus” chapter XXVII
It is all about pre-conceived ideas and trying to make the evidence fit the theory.
The pre-conceived idea was that the crew had been flying in poor visibility, suddenly saw the mountain in front of them, and attempted a violent evasive maneuver. Mahon could not reconcile this with the CVR’s “Joe Cool” attitude of the pilots with absolutely no sudden exclamations or expression of alarm.
Mahon then looked at two very significant pieces of information
- He had expert opinion that such violent rudder travel could not have been caused by pilot input.
- He noticed a cautionary note that auto-pilot data had some doubtful information because of a break in the tape.
Shift the synchronisation by a few seconds and a completely different picture emerges.
The break in the tape had caused difficulty synchronizing the FDR and CVR events.. The transcriber, acting in perfectly good faith, believing that there must have been at this point a fault in the electronic readout sequence moved the synchronisation to match the go-around power call and what was obviously (to him) a panic evasive maneuver.
Put the FDR/CVR synchronisation back to its original position and you now have:
The wing rocking was caused by HDG SEL being pulled and the aircraft starting to turn right to the previously selected heading. Then when HDG SEL was turned to straight ahead the aircraft rolled to the left to correct.
Impact then occurred in a left wing down attitude so the #1 engine hit first and caused the aircraft to slew violently to the left .
There was also a violent movement of up elevator at the same time as a pitch attitude change from 5 to 11 degrees nose up
Now we can have
control surface deflections being caused by the heading and attitude changes (inertia etc) which is the exact reverse of what had been assumed.
This is supported by the fact that there was no aileron/spoiler deflection with the supposed panic left turn.( Pilot not bothering to use ailerons in a rapid turn?) However this is consistent with an impact almost wings level, slewing left and the aircraft pitching up as it slid up the slope.
Thus when you say
At this point, the GPWS sounds, the captain calls for go-around power and there is a sudden manual application of LEFT rudder.
It contains a significant error. The two events did not occur at the same time. The call for go-around power was before impact; the rudder deflection was after (during) the impact and it was not a manual input.
From all this it becomes obvious that
- The crew never saw any terrain ahead of them.
- There was no panic evasion manouvre attempted.
So your question
…. why a pilot who is certain he is in the centre of McMurdo Sound would decide to turn left to climb out, because Erebus and Mount Bird would be to the left.
… is moot. They did not decide to turn left.
Mahon says:
The mistake they made was to first postulate what they thought had happened, and then treat all information which did not fit their theory as being not correct.
So here we had this investigatory defect revealed in startling form. The transcribers disregarded the simple facts which the 'black box' was telling them and substituted their own version of what it was trying to say.
You might not have a very high opinion of Mahon, but in the example above he certainly managed to resolve the problem you were having with some of the evidence.
(edited for crappy grammar)