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Eric Mc

77,757 posts

152 months

[news] 
Friday 12th October 2012 quote quote all
Whatever about DC-10s (what's an MD-10?), there does seem to be a problem with hard landings on MD-11s - which appears to be poor elevator authority just before the flare.
Most MD-11s are now used as cargo aircraft so any recent accidents have resulted in low or no loss of life.

Justin Cyder

12,624 posts

36 months

[news] 
Friday 12th October 2012 quote quote all
Eric Mc said:
I was specifically referring to the precise conditions as set up for this programme -

airliner on a landing approach with a deliberately excessive rate of decent.

I can think of very few accidents - even accidents that happened during the landing phase - that were caused by an exceessive rate of decent AND with the undercarriage lowered at the same time.
Eric Mc said:
Nice - I always like well mannered debate.

20 years you say -

Sioux City 1989 - 23 years
Kegworth - 1988 - 24 years
Delta Fort Worth - 1985 - 27 years
And I'm pretty sure the Eastern Airlines 727 accidnt must at least 30 years old

All very different accidents.
rolleyes

We can have the debate Eric, but you specifically asked about accidents with undercarriage down. Then when I provide them, you pick fault on the dates. Do you wonder why it is you receive a disproportionate number of ill mannered responses? I wonder what's in it for you, I really do.

Eric Mc

77,757 posts

152 months

[news] 
Friday 12th October 2012 quote quote all
OK - I now see that it's my fault that you are rude. That's OK. I can live with that.

It wasn't just landing gear down accidents I was talking about. It was landing gear down on approach coupled with a high rate of decent.

Most landing accidents are not specifically down to high rates of decent. They are usually due to misalignment with the runway, failure to operate proper approach procedures or runway over runs. The rate of decent is not usually the issue.

There are exceptions, of course. The wind sheer accidents you mentioned would fall into that category - but they are all quite a long time ago now and much work has been done to train flight crews into handling wind sheer on approach and the number of incidents have dropped dramatically since the 1985 Delta L1011 crash at Dallas.
The DC-10 crash at Sioux City (also over 20 years ago now) did feature a high rate of decent but that was due to the fact that the aircraft was virtually uncontrollable - and the crew performed magnificently to get the aeroplane anywhere near the airport at all. In other hands, it might have just fallen out of the sky like a stone. It was a very untypical accident.

In the early era of 727 operations (1963 to around 1966) there were definitely a number of accidents where the crew allowed the 727 their aircraft to sink far too fast on approach. The Channel 4 experiment would have been very useful in 1965 - but less so now.


Edited by Eric Mc on Friday 12th October 09:30

IforB

5,280 posts

116 months

[news] 
Friday 12th October 2012 quote quote all
I don't know what you two are arguing about really. You are both talking nonsense.

What on earth is a crash "caused by an excessive rate of descent with the gear down"?

Every accident has a myriad of causes and the smashing into the ground thing is just a consequence of something else.

Of the list put up, only the DFW crash is similar and that was caused by a microburst on approach which smacked the thing into the ground. The rest all hit the ground obviously, but then again everything does, gravity tends to ensure that happens...

Eric Mc

77,757 posts

152 months

[news] 
Friday 12th October 2012 quote quote all
True.

I was debating whether the staged accident replicated much of what would be likely to happen in real life.

Such experiments are only worthwhile if they give us new and meaningful information that can be incorporated in new airliner design.

I'm not sure that deliberately slamming an old 727 into the ground at a high sink rate with the gear down tells us an awful lot that wasn't known already.
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onyx39

6,208 posts

37 months

[news] 
Friday 12th October 2012 quote quote all
Eric Mc said:
True.

I was debating whether the staged accident replicated much of what would be likely to happen in real life.

Such experiments are only worthwhile if they give us new and meaningful information that can be incorporated in new airliner design.

I'm not sure that deliberately slamming an old 727 into the ground at a high sink rate with the gear down tells us an awful lot that wasn't known already.
I got the impression that a lot of the information they were trying to glean was about how the occupants and interior would behave in an accident (in terms of rapid decelaration.)
On that basis, the TYPE of impact is irrelevant as long as the rapid decelaration can be replicated?

Munter

25,379 posts

128 months

[news] 
Friday 12th October 2012 quote quote all
Given I already thought:
a)Sit over the wings as that's the strongest part of the air frame. Front or back can snap off. But that usually finishes as a chunk.
and
b)Debris is as likely to kill you as anything else. Therefore the benefit of getting your head down between the seats has to be good.

I'm not sure we learned anything much except if you try and crash a plane it really annoys people on the internet that you didn't do it their way (which as they are from the internet is clearly superior).

Eric Mc

77,757 posts

152 months

[news] 
Friday 12th October 2012 quote quote all
onyx39 said:
Eric Mc said:
True.

I was debating whether the staged accident replicated much of what would be likely to happen in real life.

Such experiments are only worthwhile if they give us new and meaningful information that can be incorporated in new airliner design.

I'm not sure that deliberately slamming an old 727 into the ground at a high sink rate with the gear down tells us an awful lot that wasn't known already.
I got the impression that a lot of the information they were trying to glean was about how the occupants and interior would behave in an accident (in terms of rapid decelaration.)
And that was fairly extensively covered in the 1984 test conducted by NASA and the FAA.

shakotan

6,981 posts

83 months

[news] 
Friday 12th October 2012 quote quote all
Otispunkmeyer said:
Just wondering actually.... the chase plane isn't quite fast enough. What if, once the pilots had bailed, the speed of the 727 crept up a little? then flew slightly out of the poor range of the radio controllers? What was their contingency for that? Lol an aircraft full of dummies flying in a straight line over america... would of been interesting!
The 'plane was already set into a decent when the pilot baled, the remote control only made small adjustments, so the 'plane still remained in decent. Had the RX lost signal, the 'plane still would have crashed regardless, just not as close to the impact site.

onyx39

6,208 posts

37 months

[news] 
Friday 12th October 2012 quote quote all
shakotan said:
Otispunkmeyer said:
Just wondering actually.... the chase plane isn't quite fast enough. What if, once the pilots had bailed, the speed of the 727 crept up a little? then flew slightly out of the poor range of the radio controllers? What was their contingency for that? Lol an aircraft full of dummies flying in a straight line over america... would of been interesting!
The 'plane was already set into a decent when the pilot baled, the remote control only made small adjustments, so the 'plane still remained in decent. Had the RX lost signal, the 'plane still would have crashed regardless, just not as close to the impact site.
May have even been closer to the "target"!

BliarOut

60,091 posts

126 months

[news] 
Friday 12th October 2012 quote quote all
Eric Mc said:
True.

I was debating whether the staged accident replicated much of what would be likely to happen in real life.

Such experiments are only worthwhile if they give us new and meaningful information that can be incorporated in new airliner design.

I'm not sure that deliberately slamming an old 727 into the ground at a high sink rate with the gear down tells us an awful lot that wasn't known already.
That the internal wiring is a hamper to rapid disembarkation. You could improve survivability for a relatively low cost by improving the wiring harnesses...

GregE240

10,839 posts

154 months

[news] 
Friday 12th October 2012 quote quote all
One question from last night....immediately after the crash, the engines (or at least 1) was still running?

So why wasn't it still moving? Had it dug itself in?

Eric Mc

77,757 posts

152 months

[news] 
Friday 12th October 2012 quote quote all
Not enough thrust to overcome the mass and the friction of the aircraft sitting on its belly.

shakotan

6,981 posts

83 months

[news] 
Friday 12th October 2012 quote quote all
GregE240 said:
One question from last night....immediately after the crash, the engines (or at least 1) was still running?

So why wasn't it still moving? Had it dug itself in?
Plus the throttle was only set to just about maintain lift so that the chase 'plane could keep up!

Eric Mc

77,757 posts

152 months

[news] 
Friday 12th October 2012 quote quote all
It did seem to be generating a fair amount of poke though. With the cockpit essentially removed during the impact, I am pretty sure the throttle settings left by the crew before they departed were completely messed up by the cockpit being taken off, throttle positions moved on impact etc. I was surprised that one of the engines kept running. I would have thought that an airliner would have some sort of inertia cut-off switch - as is fitted to most cars these days.

Roop

5,996 posts

171 months

[news] 
Friday 12th October 2012 quote quote all
shakotan said:
Otispunkmeyer said:
Just wondering actually.... the chase plane isn't quite fast enough. What if, once the pilots had bailed, the speed of the 727 crept up a little? then flew slightly out of the poor range of the radio controllers? What was their contingency for that? Lol an aircraft full of dummies flying in a straight line over america... would of been interesting!
The 'plane was already set into a decent when the pilot baled, the remote control only made small adjustments, so the 'plane still remained in decent. Had the RX lost signal, the 'plane still would have crashed regardless, just not as close to the impact site.
The r/c system (assuming line of sight) is good for 10km with standard antennas. They will also have had a failsafe programmed to put the a/c into the deck in case of extended loss of Tx signal.

LukeSi

5,319 posts

48 months

[news] 
Friday 12th October 2012 quote quote all
Aircraft should be crash tested in a similar fashion to how cars are hehe That would be fun to watch on youtube.

garyhun

16,586 posts

115 months

[news] 
Friday 12th October 2012 quote quote all
LukeSi said:
Aircraft should be crash tested in a similar fashion to how cars are hehe That would be fun to watch on youtube.
Like this you mean

http://www.youtube.com/watch?v=l7eI4vvlupY

dr_gn

8,992 posts

71 months

[news] 
Friday 12th October 2012 quote quote all
Didn't watch it all, but:

Did anyone else notice the pool of liquid under the nose of the black chase plane when they were starting the engine? Thought it looked a bit odd at the time, especially since it had gone/evaporated by the time the engine had been running a while.

Is the "crash position" primarily to stop you from submarining under the seat in front?

Did they deliberately not want a fire in order to preserve the results - how did they prevent a fire?

Simpo Two

60,434 posts

152 months

[news] 
Friday 12th October 2012 quote quote all
dr_gn said:
Is the "crash position" primarily to stop you from submarining under the seat in front?
Submarining is when you're not wearing a seat (lap) belt. Crash position I think is simply to stop you smashing your face into the seat in front under sudden deceleration.

dr_gn said:
Did they deliberately not want a fire in order to preserve the results - how did they prevent a fire?
There did seem to be some odd editing, and the whole thing seemed to be remarkably amateurish. Almost as if it was paid for by a second-rate TV channel looking for something sensational.

Surprised the nose broke off though.
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