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CONCORDE ACCIDENT - PART 2

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CONCORDE ACCIDENT - PART 2

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Old 29th Aug 2001, 23:55
  #21 (permalink)  
 
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I wasn't going to rise to this.

OK, so casualties (even fatalities) are very likely in an off airfield landing (Nimrod in the Moray Forth, BTW - a ditching in a Comet where no-one died).

But show me ONE loss of control/departure/spin/ground impact where there were any survivors at all.

And let's not get anal and pedantic about 'stuffing the nose down' - you know what I meant.
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Old 30th Aug 2001, 00:15
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Jackonicko, this is getting stupid and old. Do you really believe that the Captain planned to do a "loss of control/departure/spin/ground impact"? Of course you don't (I hope)! Since crash landing wasn't an option, the Captain took a neck or nothing decision to try to reach Le Bourget. Unfortunately there was probably no cure at that point.

If you mention "why didn't he just land straight ahead?" in your article you will IMO take away some of your credibility.

Btw. as mentioned in the previous thread a delta wing doesn't stall at all (as far as I recall even the late Captain Trubshaw mentioned that in the media after the crash).

[Edit] You didn't specific mention stall anywhere. But a lot of others do. Just before you will be all over me

[ 29 August 2001: Message edited by: cosmo kramer ]
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Old 30th Aug 2001, 01:20
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Wino:
Yes, passengers and crew have walked away from off airport landings in transport category jets! You saw the earlier photo of the Varig 707 crash landed outside Paris where the crew survived and lived to fly another day. (My message on previous page).

In the following photo you see the 737-300 put down in a farmer's field outside New Orleans after dual flameout. Everyone survived. With only superficial damage to the landing gears, the airplane was subsequently stripped of cabin seats and galleys, defueled to minimums and flown off by Boeing test pilots.

I'm sure that somewhere in your AA flight manual you've come across a little known paragraph that says something to the effect: That these emergency or abnormal procedures do not cover all cases or events, but are designed to provide guidance for most inflight emergencies and abnormalities. These published procedures are not intended to limit the crew's good judgement and common sense....

In other words, sometimes you've got to think "outside the box" and do what's unpublished in order to stay alive.


click it

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Old 30th Aug 2001, 02:01
  #24 (permalink)  
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I suspect that, once the speed fell below the 3-engine zero rate of climb speed, Capt Marty did not have many options. The 'forced landing' issue is simply not relevant. The large drag rise as IAS decays in a delta soon reaches a point where a vast increase in thrust is required to avoid further deceleration - and even more to accelerate and climb. All he could do was to try and make Le Bourget, but for whatever reason he was unable to maintain control and the aircraft departed controlled flight. Perhaps the IAS fell below Vmca2 as the No 1 engine failed? Who can be certain? But we can certainly be sure that he was trying his best.......

[ 29 August 2001: Message edited by: BEagle ]
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Old 30th Aug 2001, 02:15
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Wino,

Not forgetting the Scandi MD-80 landing in a field in Stockholm after bilateral engine failure. Although some injuries, so I'm not sure everyone 'walked away' by the strictest of definitions, all survived AFAIK.
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Old 30th Aug 2001, 02:44
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Cosmo,

I'm not suggesting he spun in deliberately. But how many times did the FO draw his attention to the airspeed? And your contention that crash landing wasn't an option is facile - if he couldn't maintain height, he had to maintain airspeed and crash landing was the only option - though it may have been not much of a choice.


Wino

Noted your new PS. No disrespect intended. Was merely demonstrating that two pros (both ATPLs, one a current FO on twin-jets, one a Captain on something else) couldn't agree. I don't think anyone believes in the old OP Jones image of Captain's infallability any more, describing you as I did was meant to underline the fact that you're a pro with an ATPL, (and jet qualled) not some amatuer PPL monkey or 'untermenschen CPL'. (That, by the way, is a joke. Many P and CPL holders have colossal knowledge and experience. I have personally taken the controls at more than Mach 1 (LIghtning, year dot.) and naturally that makes me an expert on all things supersonic........

Or not!

(Plaintively).
Can we now get back to what went wrong before the aircraft crossed the main road, and finally cease wittering on and on and on and on about force-landings, etc.?

The weight issue, the fullness of the tanks, the undercarriage spacer, the poor decision to shut down an engine etc. are more important issues, and we haven't yet come to any conclusions.

[ 29 August 2001: Message edited by: Jackonicko ]
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Old 30th Aug 2001, 14:46
  #27 (permalink)  
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Here´s a picture of the SAS MD81. Both engines destroyed climbing out of 2-3000 feet, on dec. 27 1991.
120 some pax! 1 serious injury (broken back), some minor injuries, the rest walked off.
Off airport, with no rescue equipment. 6-10 tonnes of fuel (dunno exact, but that would be a normal amount for STO-CPH trip)
But see, they landed on a snow covered field, that may have saved them from turning into a big fireball! http://www.airdisaster.com/photos/sas751/4.shtml

[ 30 August 2001: Message edited by: Hung start ]
 
Old 30th Aug 2001, 18:21
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Jacko:
As to the alleged overweight condition I wouldn't attribute that to a causal factor of the crash nor of being responsible for a tire failure. An airplane with a MTOW of 185,000 kg to be overweight by 2% is relatively insignificant. Besides, in the case of this crash, at the time of rotation enough fuel was already burned off and spilled out of the wing to put the airplane below MTOW. So, in fact at liftoff the airplane was not overweight.
As to the potential tire overload during taxi, that's not significant either because tire loads during taxi are much less stressful than at 180+ kts during heavy weight takeoffs. Imagine also the potential tire overloads during a rough touchdown. Keep in mind also that the boggie gear is designed to carry the overload of one blown tire. Proper inflation is more critical than momentary overloads. In fact maintenance procedure of replacing a blown tire includes the simultaneous replacement of the "good" tire on the opposite axle, because that tire had absorbed the overload of the blown tire.
Obviously there is lots of redundancy in tire strength.
The absence of a BA modified deflector shield is altogether more significant as it could have helped in deflecting some pieces of rubber from the wing and from the engine intakes.
During any MTOW on any airplane it's unknowable whether or not the airplane is actually above MTOW. Because individual passengers and carry on luggage is not weighed. Formulas are used for winter when passengers carry heavier clothing, and formulas are used for summer when passengers carry lighter clothes. And formulas are an approved method.


edited for error: deflector vs. spacer. Thanks Spag.
[ 30 August 2001: Message edited by: GlueBall ] Typo.

[ 30 August 2001: Message edited by: GlueBall ]
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Old 30th Aug 2001, 18:51
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The absence of the spacer is altogether more significant as it could have helped in deflecting some pieces of rubber from the wing and from the engine intakes.
Is there a confusion here? The Air France Concorde that crashed was missing a spacer on the landing gear that keeps the wheels aligned and properly separated. That was because it was inadvertently not replaced after maintenance some time earlier. As I understand it, all Air France Concordes also lack a protective shield that BA has installed on the undercarriage of its Concordes, to help deflect any debris from blown tyres away from the wing.

You talk about the 'missing spacer', but it sounds like you mean the 'missing shield'. There is no way the missing spacer could have deflected debris, had it been present. The worries about the missing spacer is that it might have slowed the aircraft's acceleration and induced a yaw because of the misaligned wheels.

Let's make sure we don't get ourselves any more confused than we already are.
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Old 30th Aug 2001, 19:19
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Spag:
Correct. Deflector shield, not spacer.
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Old 30th Aug 2001, 19:33
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Reagrding Glueball's comments about margins and redundancies in compoenents and the likelihood of their being a contributing factor to the wreck -

I've read this kind of thinking in many places and as an engineer, it bothers the heck out of me. I hope that this is not common thinking among aircrew.

Sure, engineers design margin into most things, and in the airplane business, those margins are very well-defined and specifically tested. So far, so good.

But the limit - eg the MTOW printed in the owner' manual - is not a black-and-white thing. IOW, just becauseyou are at or below that limit, does not mean that the performance of (insert part name here) will be as every bit asgood as it will for every lower loading condition. As you approach that limit, the margin designed into the part is consumed in direct proportion.

If you are at the limit - or, as it appears in this case, if you exceed the limit - you start eating margin even more rapidly, because now the part that you have stressed above its intended limit may now be asked to accomodate another failure in another area.

Bear in mind also that the analysis and testing used to set that design limit and margin of safety is only as good as the limits under which it was performed. For example, as in this case - the MTOW is intimately connected with the capacity and the margins of the tires. But did those calculations include the possibility that the wheel specer mentioned - which I understand keeps the tires from touching - was omitted? If they did not, and I doubt that they did - now you have an unknown eating away at your margin, which you have already, knowingly, largely consumed.

A single excursion to the margins is usually tolerable. It's the multiple drains upon the margins of a design which lead to catastrophic failure. Some of them may be unknown and unknowable. And it's often the "stepping" of limits which ends users up in the soup - the thinking that says 'we've operated this way before, that means we can again, and again, and again, and we will still have the same margin at this level of operation as we had at lower levels."

For a perfect case study of how this sort of thinking leads to bad outcomes, may I suggest "The Challenger Launch Decision" by (?) Vaughan. A classic example of working at and beyond the margins, and what may result from.

llater,

llamas
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Old 30th Aug 2001, 20:11
  #32 (permalink)  
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Pse don't take offence, but for a moment I thought that the AAIB had been closed down by the powers that be, and had been replaced by a group of pprune accident experts.
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Old 30th Aug 2001, 20:44
  #33 (permalink)  
 
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JacKo:
As to the missing spacer resulting in a potential drift to the left side: Doubtful significance. It is not altogether uncommon for a heavy jet, for example, to have a dragging brake, an anomaly easily overcome through initial nosewheel steering and aerodynamic rudder steering. It's more probable that the jet had drifted to the left because of degraded No.2 engine/afterburner output from early FOD ingestion (asymetric power), and before full aerodynamic rudder authority became available, or perhaps because Marty was late in applying sufficient opposite rudder.

The fact is that the jet got airborne, got to 200 feet and stayed airborne for more than one minute with sufficient control authority to give the crew a choice of a controlled crash or a stall/uncontrolled crash. Everything else is ancillary. The declared takeoff weight, the metal strip, the tire disintegration, the fuel tank puncture, the engine failure, the spacer, the tire pressures, the missing deflector, the fire....all stuff over which the cockpit crew has no direct control over.

From a pilot standpoint I'm given to fly an airplane that is supposedly airworthy, proberly maintained and properly loaded by competent ground staff. I don't know whether the tires are at 200 psi or 175 psi, and I don't know whether we have 10 tons of belly freight or 12 tons or whether or not the freight was weighed properly or correctly converted from kgs to lbs.... But I do know that people make mistakes and that not all data that is presented to me on paper is therefore necessarily correct.
Upon takeoff I may have to deal with a C.G. that's different from what was advertised on the Weight & Balance and different from the takeoff stabilizer setting. I may have an engine failure, I may have smoke from an air conditioning pack. But once airborne I have to adapt and deal with it. I have no choice but to work with what I've got.

And just as the Concorde crew faced an unimaginable inflight terror, there should never be a moment for any pilot to give up the struggle to maintain control of his machine. Level wings with sufficient airspeed is the ultimate ingredient for maintaining control.
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Old 30th Aug 2001, 21:12
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Senior Llamas:
I admire mechanical and structural engineers. To be sure, I am thankful for the built in margins without which we'd all be deader than dead.
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Old 30th Aug 2001, 22:16
  #35 (permalink)  
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Glueball - it is the culture which perhaps leads to departures outside Perf A limits which is being questioned, not Capt Marty per se.

Limits are limits. Whilst there may well be a margin of fat in RTOW/ATOW, you simply do NOT know how much. If I ever had a pilot examinee of mine paying lip service to RTOW, he would be grounded immediately. No quarter given! Commercial pressures notwithstanding, any compromise of mandatory safety margins is illegal and must never be permitted.
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Old 30th Aug 2001, 22:22
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Yes, the Concorde got airborne, and rose to some 200 feet. But I find it hard to dismiss the overweight problem and the missing spacer.

The higher the weight, the longer the takeoff run. Similarly, the missing spacer may well have slowed the acceleration of the aircraft, if not before the puncture, definitely after it.

Keep everything else the same and give Marty some extra speed when he pulled the Concorde off the ground (to avoid hitting the 747), and he would have had more options. Maybe he might even have made that tantalizingly close Bourget runway.

That ignoring the change in wind direction had no effect on the crash is illogical on the face of it. Had the Concorde switched runway, how likely is it that it would still have hit the metal FOD and burst a tyre?

I can accept that, as the BEA concluded, the tyre failure and subsequent fuel leak and fire were likely the primary causes of the crash. Not listing many of the other items pointed out in this thread and previous ones as at least contributory causes seems wrong, to me. And dangerous, in that it means little is likely to be done to address these problems.
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Old 30th Aug 2001, 22:48
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Hasn't Bof made a valid point?
On the one hand, we rightly criticise the 'rentaquote' types whom the media wheel out to give their 'expert' views (ie speculation) after an accident and, on the other, respond to a journalist's questions on this open forum.
To his credit, Jackonicko makes no secret of the fact that he wants the information for professional use. We know that journalists thrive on sensationalism yet, despite Jacko's own comments which suggest he wishes to 'expose' an alleged cover-up, many people seem to all too ready to assist.
Let's not forget that the media/Press is fickle. When BA decided to continue Concorde flights following the accident, it was 'Well done, BA.' for a few days. But, as soon as Concorde was grounded, the tone changed completely and the Press revelled in scare-mongering stories about Concorde being a death-trap which should be grounded!
Personally, I can't wait to see Concorde fly again - and would happily have flown on it without any of the mods which have now been made.
Good news doesn't sell newspapers or make good TV documentaries. Idle speculation is so often reported in the media as 'a source in the industry'.
I'm only an outsider, but why anyone would want to help the Press with 'leads' when experience shows that the end-product is bound to be unfavourable to the industry is beyond my comprehension.
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Old 30th Aug 2001, 23:32
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I've been watching PPRuNe for a couple of years and contributing occasionally for a little less, and in that time, I've seen most of the threads that pertain to aircraft accidents of various kinds. One attitude that continues to resurface is the: "stop making uniformed guesses and leave it to the experts".

Now, I appreciate that we may not all be expert accident investigators, and we may not have all the facts at our disposal but consider this. If I was leading an accident investigation board, and I wanted to make damn sure that my team left no stone unturned and no possibility unexplored, I could do a lot worse than assemble and eclectic group such as this for a brainstorming session.

The people who contribute to this BBS come from backgrounds which include pilots, cabin crew, flight engineers, ground crew, ATC, aircraft technicians, design engineers, accident investigators and yes, even the bean counters!

What I'm saying is that although we aren't the acknowledged experts in charge of the official investigation, it does no harm for it to be discussed, and I certainly don't think it's necessary to have a gag placed on us so we have to wait like sheep for the official investigation results.

For example, a lot of people have serious reservations about the official version of the Egyptair crash, and we know that politics can often distort or conceal the truth. I think it is sensible, and quite acceptable for a BBS such as this to be discussing aspects of the investigation and asking questions of the official investigation conclusions.

On a different note, I echo one of the earlier contributor's concerns with regard to besmirching the name of a deceased pilot. It is true that no one wants to speak ill of the dead, and I sincerely hope that no relatives or close friends of the flight crew are exposed to all this supposition and theorising, but it is certainly not acceptable to whitewash over the failings (if there were any) of anyone who may or may not have contributed to such a tragedy simply, because they themselves are dead. After all, who speaks up for the other hundred or so people who lost their lives and who placed themselves in the hands of the flight crew?

A fine man he may have been. A great pilot he may have been. But even the best of us make mistakes, especially in difficult and stressful situations such as this must have been. If (and I stress the word "if") he made any mistakes which could be considered to be contributory, then everyone has a right to know it, not least to help prevent future similar tragedies.

Death makes you neither infallible nor heroic, although it may be tempting and entirely natural to believe so.
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Old 31st Aug 2001, 01:07
  #39 (permalink)  
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I bow to your arguments Covenant. Thanks for an excellent post. A well balanced well written opinion.
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Old 31st Aug 2001, 01:34
  #40 (permalink)  
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Very, very well said Covenant !
This afternoon, Passing through CDG, there was one of the AFR Concorde parked, dozens of guys working around it in the rain...I am told that lots of maintenance staff comes on their off days to make sure it will fly again.
I Hope they succeed..
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