Paul Holmes and Erebus
The needle on the instrument panel points to the station regardless of where you are relative to it so you need to know the aircraft heading first to get any idea of where you are ( unless you are directly overhead). Think carefully before answering that one though.
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If you had the track plotted on chart/atlas, you could use the TACAN as a cross-check (eg, "If I'm here, then I should be x miles from the TACAN. Am I?)
The problem was that he only received the signal from the TACAN for a very short period.
If you look at p15 of the Mahon Report, he has the assumed track and the actual track, with various distances to the waypoint marked off. If the TACAN signal was being received by the aircraft and the check was done at 43 miles to the assumed waypoint, it would have given a distance of 43 miles to the TACAN, whereas it should have been 48. If done at 34 miles out, the distance would have been 34, whereas it should have been 41. And if done 26 miles out, the distance to the TACAN would have been 26, where it should have been 36.
The problem was that he only received the signal from the TACAN for a very short period.
If you look at p15 of the Mahon Report, he has the assumed track and the actual track, with various distances to the waypoint marked off. If the TACAN signal was being received by the aircraft and the check was done at 43 miles to the assumed waypoint, it would have given a distance of 43 miles to the TACAN, whereas it should have been 48. If done at 34 miles out, the distance would have been 34, whereas it should have been 41. And if done 26 miles out, the distance to the TACAN would have been 26, where it should have been 36.
Last edited by ampan; 21st Dec 2011 at 23:16.
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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.
TACAN - using the distance read out you get a circle of probability ie if it reads 40 miles you don't know which direction you are from the station and need back up information to determine direction. You can carry out a what is known as a DME homing procedure which determines a coarse direction and ultimately the procedure will bring you over head the station, where upon the distance displayed will be your altitude.
RADAR - if the aircraft was above 30° elevation a radar fix would not have been available. With that limitation a radar fix would be available to within a little under 5 NM by my back of the envelope calc if the aircraft was at the 16,000 LSALT.
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The only aids available to the crew were,
From "Aviation Tragedies" John King.
This aspect has been hotly debated. Many pilots flying the DC10 to the AntArctic used the weather radar in mapping mode which clearly confirmed the outline of Ross Island and the hight ground they could see through the cockpit window in the clear AntArctic conditions. The Chippindale report covered that point.
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Back to the subject at hand, the weather was within minimums for the flight path they took - certainly it was not as promising as it had been for many of the other flights, but they didn't break any rules (at least - any of those that they had not been told to disregard). Remember that they thought they were headed down McMurdo Sound and that the overcast applied only to the immediate area of Ross Island. There were enough breaks in the cloud between 2,000 and 16,000ft for the crew to make a visual descent and because they thought they were well west of where they actually were they probably did not expect the overcast to present much of a problem until they reached the immediate area of Ross Island and turned left once south-west of the mountains (the point at which Simpson had noticed the waypoint discrepancy).
In short they were expecting the overcast to be east of their position and as far as they were concerned the conditions in which they made their descent (broken cloud) would remain the same until they turned left.
Riddle me this - if NZCA and ANZ were so confident that the allegation of busting minima would prove pilot error as the primary factor, then why invent the story of them being in cloud when they crashed (which was later proven to be incorrect, but not before the press reports based on this allegation had fixed it in the public's mind)?
@prospector - I detect a logical inconsistency in your argument. Given that your position is that the crew deserve to share responsibility on the grounds that they did not go "by the book", it takes considerable chutzpah to argue that they were remiss in not using the weather radar for terrain avoidance despite the fact that Bendix expressly forbade use of the weather radar in this manner in their own operations manual. If the management pilots in whom you set so much store did use it this way then it is they who were in the wrong - if, of course, one were to go "by the book". Also, Mahon never had a "theory" of his own while the inquiry was in session - it was his job to assess the theories and evidence submitted, then formulate the most likely sequence of events and the responsibility for those events based on the quality of evidence submitted. Given that ANZ management presented only the evidence which supported their case and deliberately destroyed the rest then they really only have themselves to blame for giving the late Justice reason to distrust them.
Last edited by DozyWannabe; 22nd Dec 2011 at 00:56.
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[.then why invent the story of them being in cloud when they crashed (which was later proven to be incorrect, but not before the press reports based on this allegation had fixed it in the public's mind)?
Neither of these people were at the scene at the time, so one theory is as good as the other.
Nobody yet has come up with an answer as to why the wx radar in mapping mode did not paint the rock cliffs around Ross Island, remember, the dark pieces they saw in the distance and mistook for something else? In that mode it would not be used as a primary navigation aid, but it would certainly be of assistance in determining, or confirming position.
If the management pilots in whom you set so much store did use it this way then it is they who were in the wrong
AMC890,
The needle on the instrument panel points to the station regardless of where you are relative to it so you need to know the aircraft heading first to get any idea of where you are ( unless you are directly overhead). Think carefully before answering that one though.
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Last edited by prospector; 22nd Dec 2011 at 01:35.
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Nobody invented anything, iPeople were trying to figure out why they flew into Ross Island without seeing it. Vette came up with his explanation of vector whiteout, which is a possibility, but only a theory, Chippindale came up with his theory that they may have flown into cloud, which at that altitude and those conditions was a distinct possibility.
For whatever reason, Chippindale promoted the "in cloud" theory - probably because it was the most obvious explanation at the time - and subsequently refused to budge from that position even when confronted with evidence that made it unlikely. So he was as inclined to discard evidence that cast doubt on his conclusions as anyone else involved.
Nobody yet has come up with an answer as to why the wx radar in mapping mode did not paint the rock cliffs around Ross Island, remember, the dark pieces they saw in the distance and mistook for something else? In that mode it would not be used as a primary navigation aid, but it would certainly be of assistance in determining, or confirming position.
That statement is about as accurate as your idea of the use of an NDB, These pilots were in real VMC conditions, and they could visually see Ross Island and Mt Erebus and compare what they could see with the radar readout.
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Originally Posted by DozyWannabe
then why invent the story of them being in cloud
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Except that Vette went to the trouble of obtaining weather data from that area at that time and discovered that there was no cloud at any level below approximately 2,500ft,
Surely not from photo's recovered from the wreckage. There were no photo's recovered that had been taken to the South. Who would want to take a photo of cloud??
. I think the reason for this was stated by Mahon - namely that the weather radar relies on moisture to provide a return picture and ice in the Antarctic is *dry*.
and if they had been in the kind of VMC confronting Collins would have dramatically increased the likelihood of an accident had they tried.
And what sort of VMC were they in? way below the company and CAA requirements, what used to be and I suppose still is called Bloodshot
In those sort of conditions you use anything and everything to confirm your position.
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Last edited by prospector; 22nd Dec 2011 at 02:23.
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prospector/ framer
Getting back to ampan's point about placing one's trust in controllers who are human and therefore may make mistakes (or even get drunk), he questions why relying on ground aids is necessarily a safer proposition than relying on INS. What's your response?
Getting back to ampan's point about placing one's trust in controllers who are human and therefore may make mistakes (or even get drunk), he questions why relying on ground aids is necessarily a safer proposition than relying on INS. What's your response?
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The only relevant one here is the 20km vis. And it is patently obvious they never, for whatever reason had that. .
chris lz,
We have covered this in an earlier post, but, the INS was only ever designed as an en route aid, it was never intended to be the sole aid at 1,500ft, after a long flight from NZ and no updating itself from a ground station.
What were the limits for VMC, and where abouts specified?
chris lz,
T he questions why relying on ground aids is necessarily a safer proposition than relying on INS. What's your response?
Last edited by prospector; 22nd Dec 2011 at 03:22.
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Originally Posted by prospector
We have covered this in an earlier post, but, the INS was only ever designed as an en route aid, it was never intended to be the sole aid at 1,500ft, after a long flight from NZ and no updating itself from a ground station.
I recall that what we covered was that instruments on the ground, being regularly calibrated, are less likely to give false information than an INS. But in the case of radar at least, ampan's argument would appear to be that because a human being relays the radar information, that makes reliance on it subject to human error, and therefore makes it no safer than relying on AINS. Any additional thoughts?
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The only relevant one here is the 20km vis. And it is patently obvious they never, for whatever reason had that.
You could have 100 km visibility but still not see an object 5 km away if that object is invisible.
Mt. Erebus was effectively invisible.
Visibility measures work on the assumption that there is enough contrast between the object to be observed and those surrounding.
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You could have 100 km visibility but still not see an object 5 km away if that object is invisible.
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This was not an inexperienced crew, to get to be a Captain of a DC10 with an airline like Air New Zealand, even amongst the scrapping over pilot seniority when ANZ and NAC were merged, one had to be on top of the game.
When they were, if they were, told they could break the mandatory descent requirements as previous crews had done, they must have known that the weather conditions that previous flights had had was a prerequisite of these descents. What was said, or not said, is not really relevant, only the crew were facing the conditions on that day. To say they were not aware of whiteout is ridiculous, the flight engineer, who was part of the loop must have been aware for a starter, he had been down there before. They were advised that there were light snow showers in the area, their descent orders stated no snow showers. And anyone who believes the pax would have had a good view from 1,500ft, at something above 260 kts has obviously never been in that configuration.
So how did you figure the vis was 160nm?
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Find it hard to reconcile that statement. Visibility is measured from your position to what you can see, surely if an object is not visible at 5km then vis is less than 5 km?
When they were, if they were, told they could break the mandatory descent requirements as previous crews had done, they must have known that the weather conditions that previous flights had had was a prerequisite of these descents. What was said, or not said, is not really relevant, only the crew were facing the conditions on that day. To say they were not aware of whiteout is ridiculous, the flight engineer, who was part of the loop must have been aware for a starter, he had been down there before. They were advised that there were light snow showers in the area, their descent orders stated no snow showers. And anyone who believes the pax would have had a good view from 1,500ft, at something above 260 kts has obviously never been in that configuration.
but you couldn't determine any features what so ever. In every direction, up, down, sideways, was all the same shade of white.
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You could have 100 km visibility but still not see an object 5 km away if that object is invisible.
The only relevant one here is the 20km vis. And it is patently obvious they never, for whatever reason had that. .
Have you ever operated in Antarctic conditions? There are posters on here who have Antarctic experience their comments tend dispute what you seem to believe regarding visibility, white out and the ability to see things in clear air.
Why do you find it so hard to accept that in good visibility an object in the foreground can be masked by by the background. Hell even ag pilots hit trees which have they didn't see due to the background.
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Do you have any way to prove that?
And of course there was the non receipt of any VHF aids when they were well within range of these services.
Last edited by prospector; 22nd Dec 2011 at 08:45.
Yes, they flew into Ross Island.
The captain, and there would appear to no consultation with the rest of the crew before deciding on this descent,
The captain........must have been aware that there was a very good chance of encountering whiteout at the altitude he descended to
I'll repeat from my last post
"Have you ever operated in Antarctic conditions? There are posters on here who have Antarctic experience their comments tend dispute what you seem to believe regarding visibility, white out and the ability to see things in clear air."
The captain........must have been aware that there was a very good chance of encountering whiteout at the altitude he descended to
Jumping to conclusions again. How ca you say this? How do you know what his understanding and knowledge of whiteout was? It was a foreign situation to him.
Yes, they flew into Ross Island.
Sorry Prospector, that doesn't prove they were in poor visibility or cloud.
