Here is one of my replies to an earlier post on this topic:
The Captain’s decision to descend below the route MSA of FL160 was probably flawed, since under an IFR flight plan the only two ways you can do that is by descent under radar (or DME step or similar) OR by conducting a visual approach. (Of course you could cancel IFR as well). None of these things actually occurred, since a descent “VMC” is clearly not the same thing as cancelling IFR and proceeding VFR, and neither is it the same as conducting a visual approach. A descent maintaining own terrain visually still, as I understand it, requires a radar service. You cannot do that in a non-radar environment – you have to formally cancel IFR OR fly a visual approach.
Analysis of the captain’s probable thought processes reveals two fundamental pathways:
Either he decided to descend knowing that such a decision was an improper course of action, or:
He decided to descend knowing that such a decision was a valid and proper course of action.
If the first is true, then the captain was reckless and incompetent. End of story. Most, if not all of the “pilot error and nothing else” theories assume this (in many cases quite unknowingly!). It is now a natural and easy progression to apply the “command responsibility” excuse and go no further.
If the second is true, then a study of all information the captain may have based his decision on is required.
My belief is that the Captain of TE901 elected to make a descent because he knew that such an act was proper. That he was tragically mistaken is history. That this decision was neither challenged nor even queried by the other crew members shows that this misconception was shared by them all. The famous unease expressed by the operating F/E “I don’t like this” did not occur until much later.
Despite the amount of technical support available to him, (far more than what poor Ron Chippindale had) Mahon was probably out of his depth (despite producing a report that was well ahead of its time) and the fault here lies squarely with the then Attorney-General, who was foolish enough to appoint him as a one man band. Tragically the politicians of the time did not see it as "expedient" to use Ron Chippindale to assist the Commission. The political climate that prevailed required blame to be found quickly, in response to so-called "public pressure." Thus what should have been a formality turned out to be a nightmare for Chippindale, whom I recall was cross-examined continuously for seven days, and through little fault of his own, what should have been a report of "substance" has been relegated, in the eyes of many, to the back benches. That is a real tragedy, too. There is no doubt, though, that the Report of the Royal Commission set a precedent for examining systemic causal factors, a line that was taken up by ICAO in the eighties and nineties. Had this state of the art been available prior to 1979, there would have been no pathways available leading to this tragedy and therefore it would have been avoided. Both the operator and the regulatory authority would have had procedures in place back then, as they do today, to see and avoid these pathways.
The Captain of flight TE901 clearly thought he could achieve the productivity goal without compromising the safety goal. That does not necessarily mean he put the productivity goal ahead of the safety goal - it may merely show he was mistaken in his beliefs. And if so, we need to find out why.
There was only one way the captain could have prevented this accident - by electing not to descend - but there were a multitude of things the operator could have done to ensure the pathways to the tragedy weren’t available. They didn’t do any of them, mainly because they, and the regulatory authority were totally ignorant of them at the time. None of this was explored by the official accident report but this is attributable to the fact that there was simply no requirement to do so, under the then version of ICAO Annex 13 (Accident Investigation).
Now the “pilot error” pundits will point out that the Captain’s “command responsibility” means that he failed in his command role. Fair enough. It is a great pity, though, that in order to have “succeeded” in his command role he would have been required to outwit a seriously flawed system.
And no human should ever be put in that position.
dh, on a very sad day for me if the worst is true re the probable accident on Mt Egmont today. Bloody mountains.