Hi all, I'll reply to this for now and pick up the rest later, it's been a long day and I'm shattered...
Originally Posted by
ampan
I have a copy of the script, which was Exhibit 12. This is what it says: “A standard route definition will be used employing the From-Via-To format. Enter NZAA then 78S/167E this being the approximate co-ordinates of McMurdo Station.”
Was this not superseded by the INS routing? I know that they'd used the same video and script since before the 1978 switch, though I'd need to see more context in what you are quoting (namely the rest of the script if possible, along with any addenda that may have made it into their briefing wallets).
What was said at the briefing leads into the other point that requires an explanation: Why did the captain decide to turn left when attempting to climb out? The logical explanation is what was said at the briefing: “Your nav track goes to McMurdo Station.”
I don't think McMurdo Station came into it - though I have no proof for or against - I believe the decision to turn left had a far more simple explanation. They're headed southwest into Lewis Bay on INS and draw ever further into the sector whiteout, until they are confronted by full whiteout in the forward windows. Some terrain is still visible from the side windows however, to Cassin's right and Collins' left. I believe that Collins elected to turn left because his view through Cassin's window was obscured by total whiteout and he elected to turn towards the terrain that he could see through his own window, and which he knew to be low enough in terms of elevation to be safe. An additional possibility is that he knew that the western edge of McMurdo Sound was defined by the towering cliffs of Cape Bernacchi - yes, Erebus would have been to his left in that scenario, but it would have been 26 miles away.
He would have also noted that a track from Cape Hallett direct to McMurdo Station went over Erebus
I'm not so sure that he would - I think he'd have noticed and made a note of where Erebus was, but would not have tracked direct over McMurdo Station itself because the nav printout he used to plot the course (which was handled by the computer and would have been accurate to plus or minus 2 miles) stated categorically that the track would not involve Erebus directly.
It's also possible that Capt. Simpson's discovery of McMurdo's position being 27 miles west of where the programmed track took him would have been passed around the crew room in the 2 weeks between Simpson and Collins' flights.
At that point, it was imperative that he check the final waypoint, because that was the only thing keeping the aircraft from hitting terrain, and yet he did nothing.
I believe he checked it against his notes, which were based on the printout given to him at the briefing and was, as far as anyone other than Hewitt and maybe one or two people in the nav section was aware, exactly the same as the one he'd been given that morning. I used to have one of those old dot-matrix printers and the text generated by them in the pitch used is not an easy thing to read when in motion - my theory is that he copied the whole thing along with his map trace into his notebook and used that exclusively, being far more able to read his own writing than the printout (also that having material required for cross-check across two facing pages of a ringbinder is far more easy to deal with on a busy flight deck than separate sheets of paper).
I believe that the printout they were given in the morning was not referred to after departure, but used to enter the co-ordinates at the gate, requiring one pilot to verify the other's inputs against the printout, which means it may well have been Cassin doing the verification. There's scope for more tragic irony there - if they were using the printout to program the computers in order to comply with SOP (which is logical), then if Collins had been the kind of pilot to treat SOP as guidelines then he'd have used his notes as opposed to the printout and the accident would never have happened.
It would also have answered the question as to whether Chief Navigator Hewitt would have ever admitted that the error he made was much larger than they first thought, had he not been forced to by the tragic consequences.
Had Collins been told of a change I believe he would have gone and re-worked it, even if it meant delaying the flight, or postponing it altogether.
The problem only dawned on him at 1500 feet in the jaws of Lewis Bay when the F/E expressed alarm and he decided to climb out. The F/O told him it was clear to the right, but pennies were starting to drop very quickly and he recalled what was said at the briefing, realised he should have checked the final waypoint, and appreciated that Erebus might be dead ahead, which would explain the radio problems. If so, the only way out would be to the left, so he overruled the F/O, pulled out the knob, and initiated a left turn using the autopilot.
It's a workable theory certainly, and as good as many others, but for what it's worth, here's my take - it's based on the fact that the original investigation failed to take the damaged FDR tape into consideration when synchronising the CVR with the FDR, and transposed the last few FDR data points earlier in the sequence. The effect of this is to render what some consider to be violent evasive maneouvres as actually being the flight surface response to the impact - remember it bounced in the snow before disintegrating on the mountain.
So here goes - I believe that the last FDR traces are symptoms of the impact rather than an attempt to avoid it. I believe the last deliberate control inputs were the autopilot left turn and the power increase, neither of which came soon enough to avert the collision. Consequently I believe they never saw what they hit, even when they were right on top of it, as a result of full whiteout through the front windows. As I stated above, I believe that Collins' decision to turn left was based on the fact that he could not see anything out of Cassin's window and that it's possible he was more concerned with snagging something on the Cape Bernacchi cliffs than hitting Erebus, which he believed was 26 miles southeast. I think they died believing they were over McMurdo Sound.
@FGD135 - many thanks for doing the lookup of the ANZ families - it's a rare day that this happens, but I'm too knackered to face doing an evidence dive today.