Paul Holmes and Erebus
Dozy
Thats right. So on the 14th November, Simpson, who had been to the same briefing, maintained MSA even in good weather. (I imagine it was the 6000ft visual MSA not the FL160 IMC MSA).
Well I imagine Simpson could, considering he went to the same briefing but still respected the minimum altitudes even though the weather was better.
So are you saying that Simpson didn't follow the instructions to the letter? Why on earth was Simpson floating around up so high when he had been instructed to descend prior to the descent area?
Again , why did Simpson not do it then?
But Simpsons flight was in the real world, respecting the MSA's didn't do him any harm did it?
I'm not attacking the pilots here, I'm attacking your guys arguments that they are absolved of all responsibility because they were told it was safe, they were told to do it etc etc. You even say it would have happened to any crew. Well obviously it wouldn't have happened to the flight on the 14th November Captained by someone who was at the same briefing, because he was too high to hit anything.
He describes a flight that appears to have been observing the "16,000' descent limit". He goes on to describe the next flight as one that clearly wasn't.
In the prevailing conditions and knowing how previous flights had been conducted, who on here can hold their hand on their heart and say they would not have done the same?
Except in this case Wilson was the company-appointed briefing pilot who told them that the rule could be broken and Simpson was the pilot who attended the same briefing and did in fact come home safely. The crew had every right to trust that they would be too if they followed instructions which - as I said - they did *to the letter*.
Because they had been told it was safe to do so
your arguments are based around an ideal-world interpretation of what they could and should have done, rather than what they were required to do in the real-world situation.
I'm not attacking the pilots here, I'm attacking your guys arguments that they are absolved of all responsibility because they were told it was safe, they were told to do it etc etc. You even say it would have happened to any crew. Well obviously it wouldn't have happened to the flight on the 14th November Captained by someone who was at the same briefing, because he was too high to hit anything.
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Chris Iz: The problem there is that you could swap the two premises around and still have had the plane hitting the mountain. For example, assume that the waypoint was where he thought it was, and assume that the radar operator was drunk. In that event, there would have been no accident if he had relied on the AINS, but there would have been if the radar operator's double-vision had him with Erebus dead ahead, the operator therefore recommending an urgent turn to the left.
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@framer - You're replying to FGD135, not me. However, I don't have any details on Simpson's flight other than the fact he got back safely - if you could provide corroborating evidence that he did not in fact go below 6,000ft at any point during his flight I'd be very interested to see it.
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OK - do you have a link to a source for that information so I can add it to my pile? I don't mean to be a pedant, but given that it was Simpson who reported McMurdo Station to be 27 miles from the waypoint, does that mean he flew down the Sound, made a left turn at the waypoint's longitude and flew overhead? I realise the visibility was a lot better when he made the trip, so it's possible.
However, even if true, that doesn't really change anything as far as I'm concerned. Simpson was flying the "false" track and as such would have been able to descend safely to 2,000ft at the same longitude Collins did with no negative repercussions. The crux of the matter for me is that both Collins and Simpson had the same briefing materials, but only Collins flew the route with the unannounced changed waypoint. Thus the briefing (including the verbal dispensation in particular) would have been perfectly safe for Simpson, but Collins was placed in considerable danger by operating to the same parameters and restrictions.
However, even if true, that doesn't really change anything as far as I'm concerned. Simpson was flying the "false" track and as such would have been able to descend safely to 2,000ft at the same longitude Collins did with no negative repercussions. The crux of the matter for me is that both Collins and Simpson had the same briefing materials, but only Collins flew the route with the unannounced changed waypoint. Thus the briefing (including the verbal dispensation in particular) would have been perfectly safe for Simpson, but Collins was placed in considerable danger by operating to the same parameters and restrictions.
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I got it from Simpson's brief of evidence: page 9, paragraphs 32 and 33 - which is reproduced in The Erebus Papers at pages 242-3. (There's a copy currently for sale on Trade Me for NZD16.00)
Last edited by ampan; 20th Dec 2011 at 22:03.
Simpson stayed at 6000 while going down the Sound, then went down to 2000 once overhead McMurdo Station.
Sorry about that, I concede and points to you Dozy.
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- The crew's reliance on AINS resulted in plane hitting mountain
The aircraft was being navigated visually at the time of the accident.
Using my understanding of that word, I would say that the crew were reliant on the AINS for the overwater segments, but as Cape Hallett came into sight, they became less reliant on it. The "reliance level" continued to steadily decrease from then on.
-It follows that reliance on AINS is not a substitute for ground aids.
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The issue in this case is that while the withdrawal of the Williams Field NDB effectively reduced the available ground aids by 50%, the airline did not treat it as such. The written materials were in the briefing, but aside from that nothing had changed. The dispensation to descend to any level specified by the McMurdo Station controller (and the assertion that as far as the company was concerned, it superceded the 6,000ft NZCA limit) remained unchallenged. I'd bet any money you'd care to name that any disquiet on the part of the NZCA was never relayed in the briefing. As far as the company was concerned, the AINS and radar tracking from McMurdo Station provided enough defence in depth against a mistake. Unfortunately - because the change of waypoint was never communicated to the crew, and the co-ordinates of the new waypoint were never transmitted to Mac Central - both those safeguards were defeated and that left the lives of everyone on board in the hands of a crew who was navigating visually to the best of their ability but who did not know that the starting point of their descent had changed, nor did they know that the overcast they were trying to avoid was capable of hiding the mountain that had unwittingly been placed in their path. If everyone involved had followed procedure then it is likely the accident would have been avoided - unfortunately a desire on the part of the Chief Navigator to correct a mistake as quietly as possible led to disaster.
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And that surely is what the discussion has been all about, everybody, including the crew did not, for a lot of reasons, many of which have been aired on this thread, so to clain they are blameless is why I for one, and obviously many others do not agree with Holmes. Remember it was because of his publicity machine that this thread was started.
If everyone involved had followed procedure then it is likely the accident would have been avoided
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Originally Posted by ampan
Chris Iz: The problem there is that you could swap the two premises around and still have had the plane hitting the mountain. For example, assume that the waypoint was where he thought it was, and assume that the radar operator was drunk. In that event, there would have been no accident if he had relied on the AINS, but there would have been if the radar operator's double-vision had him with Erebus dead ahead, the operator therefore recommending an urgent turn to the left.
Thanks
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framer/prospector,
In addition to what ampan has written, could you explain for the benefit of the ignorant if the TACAN at McMurdo was capable of providing both distance and bearing info, thus capable of alerting the crew to their mistaken position. I'm assuming it would, but I constantly read that it was "equivalent to" civilian DME, not "VOR/DME"
Thanks
In addition to what ampan has written, could you explain for the benefit of the ignorant if the TACAN at McMurdo was capable of providing both distance and bearing info, thus capable of alerting the crew to their mistaken position. I'm assuming it would, but I constantly read that it was "equivalent to" civilian DME, not "VOR/DME"
Thanks
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chris lz: I am not sure I understand what you are asking in your first question about "a controller looking at a radar scope is what they have in mind when they think of "confirmation from ground based aids.".
The rules for controllers to identify aircraft are strict and usually laid down in the company or local orders.
They may include confirmation of passing over a ground based aid like VOR that is marked on the video map, reporting a bearing and distance from an approved aid, by confirmation over a known geographic point marked on the video map, etc.
The list is not complete but you get the idea.
Re your second question, civil aircraft cannot receive bearing information from military Tacan, they can only get distance from the Dme.
The rules for controllers to identify aircraft are strict and usually laid down in the company or local orders.
They may include confirmation of passing over a ground based aid like VOR that is marked on the video map, reporting a bearing and distance from an approved aid, by confirmation over a known geographic point marked on the video map, etc.
The list is not complete but you get the idea.
Re your second question, civil aircraft cannot receive bearing information from military Tacan, they can only get distance from the Dme.
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And that surely is what the discussion has been all about, everybody, including the crew did not, for a lot of reasons, many of which have been aired on this thread, so to clain they are blameless is why I for one, and obviously many others do not agree with Holmes. Remember it was because of his publicity machine that this thread was started.
I don't follow the logic in saying the flight crew - the last link in the chain of events that had been set up by management, ops and nav section before they even departed, remember - should be blamed for not following a rule they were told to disregard.
@chris lz : To confirm what henry crun said, the TACAN was not capable of giving directional information on civilian equipment, and neither could the NDB even when it was operational (the clue's in the name
).
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should be blamed for not following a rule they were told to disregard.
Last edited by prospector; 21st Dec 2011 at 20:03.
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Good point. So he might have complied with the badly-written "directive" (as verbally amended by Capt Wilson), but he was still subject to the general requirement to operate the aircraft in a safe manner. He knew the problem with flying under the cloud. I don't see why he had to have experienced a sector whiteout before. That's a bit like saying that you need to jump off a cliff in order to appreciate the problem with doing so.
To confirm what henry crun said, the TACAN was not capable of giving directional information on civilian equipment, and neither could the NDB even when it was operational (the clue's in the name 
).
).
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DozyWannabe: For the benefit of framer, myself, and probably many pilots reading this thread, if an NDB does not provide bearing infomation, please tell us what it does provide and how it is used.
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For anyone:
Let me make sure I have everything straight. With the NDB assumed as non operational, and the TACAN incapable of giving bearing info, the only means the crew of F901 had (at the time of their descent) to verify their position with the aid of ground instruments would be messages relayed by ATC based on their radar returns.
Do I have this right?
Let me make sure I have everything straight. With the NDB assumed as non operational, and the TACAN incapable of giving bearing info, the only means the crew of F901 had (at the time of their descent) to verify their position with the aid of ground instruments would be messages relayed by ATC based on their radar returns.
Do I have this right?