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Brand new Etihad A340-600 damaged in Toulouse; several wounded

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Brand new Etihad A340-600 damaged in Toulouse; several wounded

Old 15th Dec 2008, 13:39
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CJ, very surprising to only apply a "normal" braking when you’re gonna smash a wall !?
Do the same in a car, even as a passenger, and you will push as hard as you can on your both feet … I believe that’s just an instinctive reflex.

Actually, I don't believe that's strictly true.

You might like to read the Wikipedia entry on Brake Assist:


Quote:
Research conducted in 1992 at the Mercedes-Benz driving simulator in Berlin revealed that more than 90% percent of drivers fail to brake with enough force in emergency situations. Brake Assist detects circumstances in which emergency braking is required by measuring the speed with which the brake pedal is depressed. Some systems additionally take into account the rapidity of which the gas pedal is released, pre-tensioning the brakes when a "panic release" of the gas is noted. When panic braking is detected, the Brake Assist system automatically develops maximum brake boost in order to mitigate a drivers tendency to brake without enough force.
So for an A340 braking system (not a car) how does pedal force relate to braking force? I mean there are certainly hydraulics and other systems involved aren't they?
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Old 15th Dec 2008, 18:02
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CJ: Trace de pneumatique = bandenspoor/remspoor maar geen rubber!
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Old 15th Dec 2008, 18:57
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CONF iture, lomapaseo, Giolla, et al.

Apologies, I used "normal braking" as the opposite of skidding. Sorry if I wasn't clear enough.

"Traces de pneumatiques" is ambiguous, since it could refer equally well to skid marks as to visible traces of hard braking without skidding.
One would assume the antiskid was active.

CJ
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Old 15th Dec 2008, 19:05
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Part of the check list prior to engine running is alway to select anti skid to the off position. Generally the anti skid will be inactive anyway below a certain speed, definately in the case of a static aircraft.
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Old 15th Dec 2008, 22:09
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There is a full report available - in French.from BEA,

If it is of any help, I can translate the document.
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Old 15th Dec 2008, 22:23
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Giolla,
I've already read it, and quoted from it.
I'm pretty well bilingual English-French, so I have no problem with it.
If you're willing to translate the nearly 30-odd pages of text for free, youre welcome.
It's the kind of job I would expect to be paid for....

CJ
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Old 15th Dec 2008, 22:45
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It is too cold to go sailing......I grab your point
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Old 16th Dec 2008, 16:21
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Originally Posted by lomapaseo
So for an A340 braking system (not a car) how does pedal force relate to braking force? I mean there are certainly hydraulics and other systems involved aren't they?
Some malfunctions inhibit the antiskid which implies to limit the brake pedals action in a way to obtain a max brake pressure of 1000 psi as indicated by the gages and not risk to lock the wheels. Actually that limit is very easy to exceed if not carefully monitored.
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Old 16th Dec 2008, 19:40
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Taxiing up to 30 knots in straight line is part of the everyday operation but I’ve never felt hitting something even would it be a wall could imply so much destruction. All the photos reveal a phenomenal energy dissipation and I would easily conceive the speed and/or thrust was much higher than 30 knots and/or idle thrust.

Nobody yet dared to comment on the fact that obviously the three Main Landing Gears took an in flight status for a while ?

There is even a possibility here that the protections played another unconceivable trick :
If the turbulences were able to lift the tail up they could be well able, in the same time, to disturb the Angle of Attack censors and set them beyond the ALPHA FLOOR threshold which would have triggered the ALPHA FLOOR protection by applying TOGA thrust.

A lot to consider … Let’s see if anyone is willing to comment ?
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Old 16th Dec 2008, 20:04
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would have triggered the ALPHA FLOOR protection by applying TOGA thrust

But it didn't because the FDR traces clearly show the EPR on all four engines not rising above the test level of 1.25 at any point, and only changing after the moment of the collision when all engines suddenly reduce thrust.
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Old 16th Dec 2008, 20:22
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Originally Posted by CONF iture
... phenomenal energy ...
Just a thought: some of the aircraft kinetic energy would have been stored in its rotational inertia - it was turning, not just moving forward.
Perhaps you could explain why you find the damage unbelievable for a 30kts collision. Isn't the nose section relatively lightweight structure?
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Old 16th Dec 2008, 22:05
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CONF iture,
I don't really get your point.
The blast wall was not vertical, but angled, so of course the airframe would go up and over, and would have done so even at less than 30kts.

CJ
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Old 17th Dec 2008, 11:41
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If you drove your car into a wall at 30 knots the front bumper would be somewhere around the windscreen. It's hardly surprising that a "vehicle" the weight of an A340 would be damaged to this extent after impacting and mounting the blast fence. Plus the blast fence would have acted like a knife cutting into the fuse as it went over it. The fact they were at near take off power while all this was going on would have helped too.
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Old 17th Dec 2008, 17:29
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May have been somewhat tail-heavy, as well....
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Old 18th Dec 2008, 01:26
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Such aircraft is usually nose heavy when empty, 40 tonnes of fuel … probably not much in the tail, but with 26% CG anyone with the graph will tell ?
Also the aircraft was in straight line as shown by the nose gear marks.

Pictures clearly show multiple impacts, multiple structural deformations and failures.
Initially nose tip collides, impact visible just below ENG 2, which provokes immediate major structural failure just behind cockpit area, then another major structural failure about 10 meters further aft before ENG 1 and 2 finally contact the wall. In the same time nose landing gear detaches and flies away + major tail strike occurs.

To this point it is already a lot of energy dissipation … but that’s far from over.

Look at these left side engines, they just want to climb the wall, a 20 meters fuselage section is now on the other side of the wall, MLG is suspended in the air.
Then under ENG 3 and 4 thrust the tail moves 15 meters laterally …

Anyway, very lucky these nine persons on board … No mention if seat belt were fastened in the flight deck or in the cabin ?

Another point of interest from the CVR :
Originally Posted by page 14
« euh… cabin is… aircraft is moving forward »
« Aircraft is moving forward »
« parking brake off »
13 seconds … and that’s it ?

The full event is on video tape … no chance to see it ?


Still not many to comment on the absence of braking marks contrary to what is reported by the BEA ?

And still nobody to comment on the early crab movement of the aircraft 120 meters away from the wall, and so with only 3 tires marking the ground ?
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Old 16th Jan 2009, 15:07
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Crowd record as long it is brand new ... but no one in sight when report is out ...

What's Going On !?
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Old 17th Jan 2009, 08:46
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What's Going On !?
Business as usual....
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Old 17th Jan 2009, 17:04
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Originally Posted by CONF iture


Crowd record as long it is brand new ... but no one in sight when report is out ...

What's Going On !?
What is going on is that the French have decided not to publish their report in English. So the vast majority of pilots, you know, the people who could read and learn from this, can't read and learn from the report. Politics or cheapness or pride or whatever, ahead of safety again.
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Old 17th Jan 2009, 19:07
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punkalouver,
I'm not BEA, so don't quote me.

So the vast majority of pilots, you know, the people who could read and learn from this, can't read and learn from the report.
- Pilots? IIRC there weren't any pilots there...

- It wasn't an 'accident' in the aviation sense, since no flight was intended, the aircraft never was airborne, and there were no fatalities. A serious 'incident', yes (injuries and hull loss).

- The BEA would not have any legal obligation to produce a translation, and hence would not do so, if only to avoid arguments about the exactness of the translation, or even legal issues.

- Anybody who'd want to read and learn from the report (I'm now talking about those who would be directly and seriously interested, not the typical wannabee) can commission a professional translator. Do a word count and get an estimate. The report is now in the public domain.

BTW, don't ask me. I've done some, but I've now retired.

CJ
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Old 18th Jan 2009, 01:13
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Originally Posted by ChristiaanJ
punkalouver,

- The BEA would not have any legal obligation to produce a translation, and hence would not do so, if only to avoid arguments about the exactness of the translation, or even legal issues.

- Anybody who'd want to read and learn from the report (I'm now talking about those who would be directly and seriously interested, not the typical wannabee) can commission a professional translator. Do a word count and get an estimate. The report is now in the public domain.
In other words, as I said(slightly modified), the vast majority of people won'tread the report and learn from this.

Politics or cheapness or pride or whatever, ahead of safety again.
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