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ANZ Antarctic Crash Question  
User currently offlineKhobar From United States of America, joined Mar 2006, 2379 posts, RR: 4
Posted (5 years 6 months 3 weeks 4 days 16 hours ago) and read 5585 times:

In the recent thread about this horrible crash, a link to a video was posted. The video includes footage shot in the cabin just prior to and including the moment of impact.

One thing that stood out was the number of people taking pictures out the windows. My understanding is that they were in white-out conditions, and that begs the question: what were they taking pictures of since white-out is what it implies?

Also, I understood that coordinates had been entered incorrectly. The aircraft impacted at 500m ASL. My second question - did they know they were that low? Was that the intent?

15 replies: All unread, jump to last
 
User currently offlineZANL188 From United States of America, joined Oct 2006, 3591 posts, RR: 0
Reply 1, posted (5 years 6 months 3 weeks 4 days 16 hours ago) and read 5557 times:
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Quoting Khobar (Thread starter):
One thing that stood out was the number of people taking pictures out the windows. My understanding is that they were in white-out conditions, and that begs the question: what were they taking pictures of since white-out is what it implies?

My understanding is it wasn't a blizzard type white out with lots of snow... It was an optical illusion that created a false horizon & "hid" Mt Erebus

Quoting Khobar (Thread starter):
Also, I understood that coordinates had been entered incorrectly. The aircraft impacted at 500m ASL. My second question - did they know they were that low? Was that the intent?

They couldn't see the mountain and the terrain slowly rose beneath them.... I suspect the crew was well aware of their ASL altitude, it was the AGL that bit them.... Crew reacted to GPWS horn but it was too late...



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User currently offlineRFields5421 From United States of America, joined Jul 2007, 7607 posts, RR: 32
Reply 2, posted (5 years 6 months 3 weeks 4 days 16 hours ago) and read 5546 times:

The flight was a sight seeing flight. The sole purpose of getting on the plane was to be able to look out the windows and take pictures of Antarctica, especially the mountain.

The plane was low because that was a 'feature' of the flight - to get close to the continent. It apparently was a little lower than planned.

The 'white-out' was not a pure socked in ILS condition - but intermittent condition which caused the pilots to lose the horizon and definition to be able to tell what was ground/ ice and what was sky.

A pretty good review of the flight:

http://en.wikipedia.org/wiki/Air_New_Zealand_Flight_901


User currently offline413X3 From United States of America, joined Jul 2008, 1983 posts, RR: 0
Reply 3, posted (5 years 6 months 3 weeks 4 days 16 hours ago) and read 5535 times:

where is this video?

User currently offlineLongHauler From Canada, joined Mar 2004, 5157 posts, RR: 43
Reply 4, posted (5 years 6 months 3 weeks 4 days 16 hours ago) and read 5527 times:



Quoting Khobar (Thread starter):
Also, I understood that coordinates had been entered incorrectly. The aircraft impacted at 500m ASL. My second question - did they know they were that low? Was that the intent?

A fascinating accident. No, the co-ordinates were not incorrectly entered, they were given a flight plan with the waypoints changed. Things were not where they should be, as they were not where that thought they would be. A part of familiarization for the trip for the flight crew was landmark detection.

When it was suggested this flight plan change may have contributed to the accident, the documents were changed, and a cover-up attempted.



Never gonna grow up, never gonna slow down .... Barefoot Blue Jean Night
User currently offlineAzncsa4qf744er From United States of America, joined Oct 2003, 696 posts, RR: 0
Reply 5, posted (5 years 6 months 3 weeks 4 days 15 hours ago) and read 5476 times:

Check out Youtube and search Mt. Erebus-The Loss of Flight901

There is 8 parts and each one is about 10 minutes long. Most of your question(s) will be answered on there.


User currently offlinePlanesNTrains From United States of America, joined Feb 2005, 5793 posts, RR: 28
Reply 6, posted (5 years 6 months 3 weeks 4 days 14 hours ago) and read 5335 times:



Quoting Khobar (Thread starter):
My understanding is that they were in white-out conditions, and that begs the question: what were they taking pictures of since white-out is what it implies?



Quoting RFields5421 (Reply 2):
The flight was a sight seeing flight. The sole purpose of getting on the plane was to be able to look out the windows and take pictures of Antarctica, especially the mountain

His question was how/why they could be taking pictures if the aircraft was in white-out conditions, not why they would be taking pictures at all.

When I watched the video, that was my first thought too. 'These people are all clamoring for a window to look out of, but I thougth there was no visibility at the time of impact?'. I guess they weren't in white-out conditions afterall, but rather just lost perspective.

-Dave



Next Trip: SEA-ABQ-SEA on Alaska
User currently offlineTG992 From New Zealand, joined Jan 2001, 2910 posts, RR: 10
Reply 7, posted (5 years 6 months 3 weeks 4 days 13 hours ago) and read 5257 times:

It was the horizon that was hidden, not the ground. There was still plenty of stuff visible out the window (pack ice, icebergs, snow formations, etc)

Quoting LongHauler (Reply 4):
When it was suggested this flight plan change may have contributed to the accident, the documents were changed, and a cover-up attempted.

Remember, Justice Mahon's accusations of an organized cover-up were completely demolished by the Privy Council.


There was a fascinating thread on ppprune a number of years back, almost entirely amongst experienced heavy jet pilots, and ended completely divided (but the debate was entirely civilized and fact-based, which is what made it fascinating). Many of the contributors, who you would expect to have a vested interest in blaming the organization rather than the pilots, disagreed with Mahon's findings and maintained that the crew should not have been below the approved minimum altitude when they were uncertain of their position.

I strongly urge anyone interested in the causes of this crash to track the thread down and read it - it completely changed my perceptions.



-
User currently offlineKhobar From United States of America, joined Mar 2006, 2379 posts, RR: 4
Reply 8, posted (5 years 6 months 3 weeks 4 days 11 hours ago) and read 5159 times:

Many thanks for the info. Obscured horizon explains a lot.

I had originally thought the purpose of the flight was to see Mt. Erebus itself, and as such I expected the aircraft to be flying at a medium altitude (like, I dunno, 10,000ft) and they crashed into the mountain because they weren't where they thought they were. I see now the seed of truth in that, but only the seed.

Again, thanks for the additional info.


User currently offlineKiwiandrew From New Zealand, joined Jun 2005, 8625 posts, RR: 13
Reply 9, posted (5 years 6 months 3 weeks 4 days 10 hours ago) and read 5070 times:
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Quoting PlanesNTrains (Reply 6):
His question was how/why they could be taking pictures if the aircraft was in white-out conditions, not why they would be taking pictures at all.

from my understanding white-out can be directional - apparently the combination of reflection of light from the snow and the clouds overhead can create the illusion of a distant horizon in a given direction when in fact there may be snow covered obstacle directly ahead - whiteout does not necessarily mean that there is no visibility in any direction - from the explanations I have been given before by those better informed than I am it is could be described in some cases as an optical illusion rather than a true lack of visibility . For this reason it is possible for whiteout to be present in the forward direction of the flight without any visual impairment to the sides . ( no doubt some one can explain this a lot more eloquently and clearly than I have just triede to )



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User currently offlinePlanesNTrains From United States of America, joined Feb 2005, 5793 posts, RR: 28
Reply 10, posted (5 years 6 months 3 weeks 4 days 10 hours ago) and read 5037 times:



Quoting Kiwiandrew (Reply 9):
from my understanding white-out can be directional - apparently the combination of reflection of light from the snow and the clouds overhead can create the illusion of a distant horizon in a given direction when in fact there may be snow covered obstacle directly ahead - whiteout does not necessarily mean that there is no visibility in any direction - from the explanations I have been given before by those better informed than I am it is could be described in some cases as an optical illusion rather than a true lack of visibility . For this reason it is possible for whiteout to be present in the forward direction of the flight without any visual impairment to the sides . ( no doubt some one can explain this a lot more eloquently and clearly than I have just triede to )

Thanks for the explanation. Unfortunately, being from Seattle I am only familiar with rain-outs.  Smile

-Dave



Next Trip: SEA-ABQ-SEA on Alaska
User currently offlineVirginFlyer From New Zealand, joined Sep 2000, 4575 posts, RR: 41
Reply 11, posted (5 years 6 months 3 weeks 4 days 9 hours ago) and read 5009 times:



Quoting TG992 (Reply 7):
Remember, Justice Mahon's accusations of an organized cover-up were completely demolished by the Privy Council.

You don't happen to know where I can track down a copy of the Privy Council ruling or the Chippendale accident report online do you? The only document I've been able to find is the Mahon report (caution, it is a 66MB PDF file). I was always under the impression that the primary issue the Privy Council took with Mahon's accusations of a cover up was that it was outside of his terms of reference, not whether the evidence did or didn't support it. Without reading it though, I can't be sure.

You're certainly right that it is a subject that usually ends up with polarised opinions of who was or wasn't in the right (fact, I think you and I had that very discussion some years back...). It's a tough one really. To simplify a complex issue, one side says that if the crew had have remained above the specified lowest safe altitude, they would not have struck the mountain. Which is true. The other side says that if the navigation coordinates had not been changed (or if the crew had been made aware of the change) then the aircraft would not have been in a position where it could have struck the mountain when flying at the altitude which previous flights had flown. Which is also true. I have a feeling it is one of those debates which will never be settled.

One important thing which I think can be taken away is the importance of a thorough investigation which examines an accident in the context of a safety system, and not a simple cause-effect analysis which ignores deeper issues. ALPA in NZ has recognised Mahon for his investigation in this regard - see http://www.stuff.co.nz/national/742161

Interestingly, that article mentions ALPA are going to set up a website on the accident which will pool the material relating to the investigation. I hadn't heard that before, and I'm looking forward to seeing it.

Quote:
"It is for his sterling work, in forever changing the general approach used in transport accidents investigations world wide," said ALPA executive director Rick Mirkin.

He said Justice Mahon's family would be at an international conference of airline pilots in Auckland next year to be presented with the award.

Mr Mirkin said ALPA would also launch a website which would be the "definitive source of information in the world on the whole Erebus accident and the aftermath and the air accident investigation process that ensued, that was so instructive for so many people around the world.

"The intention is to present the facts and let people draw their own conclusions. It is not going to be a blame and shame operation," he said.



Quoting Khobar (Reply 8):
I had originally thought the purpose of the flight was to see Mt. Erebus itself, and as such I expected the aircraft to be flying at a medium altitude (like, I dunno, 10,000ft) and they crashed into the mountain because they weren't where they thought they were. I see now the seed of truth in that, but only the seed.

While there was a minimum height specified (which I cant recall off the top of my head), the flights would regularly descend below that, and I believe there were advetising photos which clearly showed the aircraft at these lower altitudes. The big issue is that when the route was changed from being down McMurdo Sound, as the crew believed it to be, to directly over Erebus, this practice of descending to low altitude took the aircraft's course into conflict with the terrain. Perhaps the most ironic twist is that the features at the entrance to Lewis Bay, where the aircraft was, were mistaken for the features at the entrance to McMurdo Sound, where the crew believed they were. Indeed, with the sector whiteout conditions being experienced, even Peter Mulgrew, who was an experienced Antarctic explorer, mistakenly identified features that would have put the aircraft down the middle of McMurdo. See the CVR Transcript published on the Aviation Safety Network's page, where Mulgrew's comments are marked as the 'guide on board'.

Here is the Air New Zealand brochure for their Antarctic flights from 1978, from this website: http://www.southpolestation.com/trivia/history/te901.html





V/F



"So powerful is the light of unity that it can illuminate the whole earth." - Bahá'u'lláh
User currently offlineRongotai From New Zealand, joined Sep 2000, 477 posts, RR: 2
Reply 12, posted (5 years 6 months 3 weeks 4 days 9 hours ago) and read 5007 times:



Quoting TG992 (Reply 7):
disagreed with Mahon's findings and maintained that the crew should not have been below the approved minimum altitude when they were uncertain of their position.

.

Until very late the crew were NOT 'uncertain of their position' , rather they were both certain AND wrong. This was for various reasons which are the cause of the profound disagreements others have described, but the 'trap' was because they were in 'sector whiteout' conditions, which is different from 'whiteout'. The false horizon optical illusion associated with sector whiteout meant that except for straight ahead the crew could see various places where rock outcrops stuck out of the ice (for example Cape Royde), and therefore were misled into believing they had perfectly clear visibility.

What made the trap complete was that the visible locations were configured like the locations they had been expecting to see if they were on the track that they thought their waypoints were guiding them along. So the crew did not know they were in sector whiteout (and had never been trained to identify it), and the visual cues led them to believe that Erebus was well to their left.

The debate over the crew's culpability lies with two factors - they had no positive identification of Erebus, only an assumed position, and they were below the safe minimum altitude. The former one was beginning to worry them when the GPWS went off ,but the latter one is highly contentious. They thought they were in VMC, but were, in fact, not. Furthermore the previous flights had routinely flown at that altitude. Just one month before Erebus the NZCAA's own safety magazine had a front cover with an NZ DC10 flying over Scott Base at 3000'. After the crash all copies of that edition were rapidly withdrawn. My copy was sent to Mahon and was never returned.


User currently offlinePA515 From New Zealand, joined Nov 2007, 924 posts, RR: 0
Reply 13, posted (5 years 6 months 3 weeks 4 days 5 hours ago) and read 4853 times:



Quoting VirginFlyer (Reply 11):
Here is the Air New Zealand brochure for their Antarctic flights from 1978, from this website: http://www.southpolestation.com/triv....html

Thanks for posting the brochure, mine was destroyed by silverfish. I thought the fare was $270, but its $299. The flights were fully booked about six months ahead, so I missed out. However, my landlord David Palmer, his brother, brother in law and father were on the flight. He was the best. There were subsequent tragedies as well. A guy I went to school with was married to a Cabin Crew member and was unable to cope with her loss.

PA515


User currently offlineSXI899 From Netherlands, joined Jan 2008, 274 posts, RR: 0
Reply 14, posted (5 years 6 months 3 weeks 4 days 1 hour ago) and read 4660 times:

As I recall reading, another thing that worked against the crew in the accident were the cliffs of the shoreline of Ross Island.
I believe it was calculated that had the ground risen gradually from the shore instead of so abruptly, the GPWS would have alerted the crew about 4 seconds earlier, which should have given them enough time to climb away from danger.
All in all, a great tragedy.

Yorden



Any Type, Any Time, Anywhere
User currently offlineZkpilot From New Zealand, joined Mar 2006, 4865 posts, RR: 10
Reply 15, posted (5 years 6 months 3 weeks 4 days ago) and read 4618 times:



Quoting ZANL188 (Reply 1):
Quoting Khobar (Thread starter):
One thing that stood out was the number of people taking pictures out the windows. My understanding is that they were in white-out conditions, and that begs the question: what were they taking pictures of since white-out is what it implies?

My understanding is it wasn't a blizzard type white out with lots of snow... It was an optical illusion that created a false horizon & "hid" Mt Erebus

 checkmark 
It is what is known as Sector White Out. The weather was actually fine in terms of visibility however with the vast expanse of white from the icesheet/mountain below and infront and with white overcast blending into this the optical illusion that is Sector White Out meant that the crew thought they had nothing in front of them. Remember they would have thought they were miles away as the wrong co-ordinates had been given to them.



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