French Concorde crash

[lomapaseo]

nothing more need be said

unfortunately it says nothing about the probability that a crash would occur following a blowout.

are we to be left to imagine what needs to be said?

just citing random statistics without benefit of weighting gain vs risk to us personally weighs on our minds until we just ignore the subject.

[PBL]

Originally Posted by SLFinAZ

nothing more need be said.

Except to point out facile thinking by someone offering an opinion on a subject on which heshe appears to know little. So here goes. lomapaseo points in out in a couple of words. It'll take me a little longer.

Originally Posted by SLFinAZ

For a modern commercial aircraft to be deemed airworthy, it must be able to survive a blowout.

Incorrect. Let's take it step by step. For a commercial transport to be deemed airworthy, it has to be certified. The document that deems it airworthy is called an "airworthiness certificate".

To be certified, it must be successfully argued that the risk of any catastrophic event is extremely improbable. "Extremely improbable" means, basically, unlikely to occur within the expected total fleet lifetime.

Originally Posted by SLFinAZ

Before the accident, there had been 57 cases of Concordes’ tires bursting or deflating. Twelve of those incidents led to structural damage to a wing or fuel tank, and six of those led to penetrations of tanks. The bottom line is that, for the Concorde, there was a 10% chance a blowout could lead to a ruptured fuel tank.

Let us accept these figures for the sake of this argument. There is obviously a missing step from this to airworthy/not airworthy. (So much for the claim that "nothing more needs to be said"!)

The missing step is: assessing the risk that a ruptured fuel tank, in the form in which it had been known from those 6 incidents, could engender a catastrophic event.

Exactly what that risk could be taken to be, in advance of the crash, is a matter I have already addressed in my blog post. Suffice it to say here that, as far as anyone could tell beforehand, it fit in the category of "extremely improbable".

So I have trouble seeing here what SLFinAZ is trying to argue. (So much, again, for the claim that "nothing more needs to be said")

PBL

[M2dude]

Concorde tyre safety

OK, could I possibly interject here with a few historical and technical FACTS? Thank you all, and please bear with me:
FACT 1: First of all Concorde was a delta winged SST, it is quite possible/probable that any viable SST would require a similar configuration.
FACT 2: Any such design (obviously) requires that the landing gear will have to nestle somewhere well within the shadow of the wing, and hence the fuel tanks. This in turn will make the fuel tanks potentially vulnerable to the effects of tyre blow-out.
FACT 3: The high rolling speed of the above design requires very high pressure tyres, themselves being more prone to fragmentation blow-outs than lower pressure tyres. These blow-outs are as the result of either FOD damage at high speed, or taking off with a part deflated tyre (due again to FOD damage).
FACT 4: To minimise potential risks you either produce a near 'blow-out' proof tyre or protect as much of the structure/systems as is possible. Technology in the 1960s, 70s, 80s and early 90s did not exist to produce a near burst proof tyre, and so modifications WERE carried out to 'beef up' vulnerable pieces of structure and electrical/hydraulic routing, as well as modifying the braking system power supplies. These modifications were as a result of experience gained through tyre failure incidents in airline service.
FACT 5: We would all have to admit in hindsight that the original Kleber and Dunlop tyres fitted to Concorde were potentially far too 'explosive'. However until the development of the superb Michelin NZG tyre in the very late 1990s there was no real technical alternative.
FACT 6: A tyre deflation detection system system was fitted to the aircraft in the late 1980s to give the crew warning of any more than a 10% deflation. The idea of this was to prevent a take-off attempt with a ruptured tyre, and worked very well, preventing many potential blow-out incidents.
FACT 7: All structural damage prior to July 2000 was as a result of HARD material impact, and not this alleged 'hydraulic' rupture, due to large soft impact material, (the tyre). There was I repeat NO experience of this prior to Gonesse.
FACT 8: BA carried out a modification to the water defelctor (or 'cow catcher') fitted to the front of the wheels. This modification was to fit a steel cable through the water deflector structure, so that in the event of a high energy tyre failure, the deflector would not disintegrate and fly off in all directions and damage the aircraft skin. After this modification was embodied THERE WERE NO MORE BA AIRCRAFT PUNCTURED FUEL TANK INCIDENTS... NOT ONE!!!! (The very last such incident was in October 1993; a full 10 years before services ended in 2003).

Every incident, every event was investigated to see if anything could be done to prevent it occuring again, or minimise the effects of such an event if it did occur. Nothing, but NOTHING was ever ignored.

Much is made of the Air France incident at IAD in June 1979, and as serious as it was (a double blow-out), I'd like to put a few things in context here. The big 'hole right through the wing' although technically true is not quite what it seemed. The hole that daylight and debris could be seen through was the single skinned and low stressed panel that was fitted over the undercarriage. (This panel could be easily removed for maintenance even). There was however tank puncturing which is always of course regarded as very serious, but the fuel loss was miniscule compared to Gonesse. This incident WAS unique in terms of the amount of structural and systems damage done, and salutary lessons were learned as a result of this.

I will not go into the why's and wherefores here of the Gonesse tragedy, I have my own opinions, based on what I know to be fact and not rumours and fantasies, that differ substantially from the BEA report, I will not share them here. But one thing we must all agree on that this was a terrible tragedy that should never have happened, and shows us all just how terrible aircraft accidents can in fact be, and no aircraft is immune from such tragedies.
One final interesting point however from all the hindsight 20/20's out there is why Kevlar linings were not fitted to the fuel tanks years ago? The awful truth is that they alone would quite possibly not have stemmed the leak from #5 fuel tank on F-BTSC sufficiently to have prevented the ensuing fire, and that on their own they were really only of limited use. This is not my opinion, but that of the chief British engineer involved with the Warton 'fire tunnel' research. The NZG tyre has to be regarded as the main preventer of such a tragedy never occurring again.

Regards
Dude

[mike-wsm]

Originally Posted by Iron Duck

Britannia 310 (close to your heart, surely?) 1,330lb/seat: commercial failure

Ah, cut to the quick, yes sir, very much so, an elegant and beautiful aeroplane, the very best ever to be produced at the Filton Rest Home for Tired Engineers.

Alas it was those silly folded Proteus engines that delayed its introduction into service when the flight test team had to traipse around the world looking for weather conditions that would freeze up that daft U-band, inherited from trying to bury the engine ahead of the main spar within the wings of the Brabazon and Princess.

Apologies to all for the thread drift, but it's all part of the Filton story. It fascinates me to look back on our past 'successes' and to see what white elephants they were in real terms when compared with those very few real success stories, where aircraft are produced in greater than 1000-off quantities. One of the key elements is humility, the ability to accept reality and adapt to it. The British national character is one of arrogance and an arrogant political system driving arrogant company management will never yield commercial success.

Footnote re my comment on weight per seat - of course there are many boxes to tick before an aircraft can become a success. My point is that excess weight is a surefire commercial killer. If you are double the weight per seat you use double the fuel per seat and carry a huge economic penalty. Even when fuel is cheap you have to appreciate your product is over-sensitive to any increase in fuel price. Sensitivity analysis is key to all engineering and economic calculations.

For M2 Dude - yes, 829, just a prawn.

I'll have to sign off here and avoid the lynch mob, many thanks for your kindness and hospitality to this armchair onlooker.

[Iron Duck]

Aviation Week

SLFinAz

As you post consists of quotes from the Aviation Week editorial, let's look at another one:

At no point in this string of events did anyone knowingly do something wrong or shirk his or her responsibilities.

So the licensed mechanic, knowingly bodging the repair with the wrong material and the wrong fasteners, did not "knowingly do something wrong or shirk his or her responsibilities"?

There is a reason why a certain material and fastening method was specified. If he didn't know the reason he shouldn't have been licensed; if he did know the reason he "knowingly did something wrong or shirked his or her responsibilities".

And, to be clear, the reason can be deduced: the correct material and method had been tested and approved; all others had either not been tested and approved, or had been tested and found wanting. Ergo, using incorrect methods and materials may cause harm.

One could argue that titanium and stainless steel were functionally equivalent for the purpose, and that stainless steel might have sliced Concorde's tyre in the same way that Ti did. But there is no argument about the quality of the repair, or the fact of wrong fasteners being used, or of the poor workmanship, and that because of this poor workmanship the strip fell off the DC10 before it had even got airborne on its next flight.

[PBL]

Originally Posted by mike-wsm

I'll have to sign off here and avoid the lynch mob

I had rather thought you were playing the lynch mob, with an intolerance for detail, a point of view to pursue, an acknowledged lack of expertise, and a lack of interest in discussing in depth with experts whether your view is sustainable or not.

I am here to have fun, which means, for me, discussing matters of interest to me in depth with those whose expertise and knowledge exceeds mine, and helping to clarify things where mine exceeds that of others. I don't see the value of judging the entire history of a major airplane in a few laudatory, or in your case pejorative, words and then signing off. But I am happy to get back to interesting discussion.

PBL

[PBL]

Adding to Iron Duck's commentary on the phrase

At no point in this string of events did anyone knowingly do something wrong or shirk his or her responsibilities

That seems like a straightforward comment, but I notice it hides a lot which is relevant to these legal events. First, I note that this can be separated into two assertions:

1.

At no point in this string of events did anyone knowingly do something wrong

2.

At no point in this string of events did anyone shirk his or her responsibilities

ad 1. The French court disagreed with this assessment. They decided that the mechanic had committed involuntary manslaughter. I don't know what the French criteria for this are. In Britain, as far as I understand British law (and I am not a professional), one major criterion for having committed a criminal act which led to unlawful killing is having indulged in "gross negligence". There is negligence, and there is gross negligence. "Knowing" plays, if at all, a subsidiary role. Exercising one's duty of care, or not, plays a major role, as I understand it.

ad 2. I think it is obvious, as it appears does Iron Duck, that the Continental mechanic did not exercise his duty of care to perform the repair according to applicable procedure. If "not exercising his duty of care" is what is meant here by "shirking his or her responsibilities", then this second statement is false. And if it doesn't mean that, then I don't know what it would mean.

I am no expert in whether not exercising one's duty of care in this case constitutes "negligence" or "gross negligence", but these concepts are not necessarily applicable in French law. As for French law, the decision is before us and the quoted statement above just contradicts it. That is easy to do from another country and another legal system.

Edit: Just to make clear my position, I re-engaged with PPRuNe in Spring 2007, because of my concern with the increasing criminalisation of transport accidents, in order to try to contact people involved with investigating the ATC side of the GOL-Legacy collision. I think, along with a majority of aerospace professionals and professional societies, that the increasing criminalisation is a trend about which to be very concerned, not just as a question of justice but also in its oft-demonstrated conflict with thorough procedures in accident investigation. I think the public interest is ultimately best served by thoroughly investigating complex accidents as to cause, and this is hindered by criminal investigations in known and well-reported ways. However, I do not think the public interest is in any way well served by ignoring legal matters, not only the matter of determining compensation but also the matter of criminal proceedings in the case of possibly-criminal action. I think we need to work to reconcile the concerns in a way which appropriately acknowledges the public interest in all these aspects. This won't happen through aviation professionals reactively denigrating legal proceedings in each instance, and it won't happen through legal professionals asserting their right to do what they do independent of broader concerns of the polity.

PBL

[M2dude]

mike-wsm
Leaving so soon? Not disputing what you told us all here, but:

I think I can recall seeing G-BOAG nearing completion.

G-BOAG was NEVER in the Brabazon hangar under that registration, she was G-BFKW. She was re-registered to G-BOAG at Heathrow, after BA decided too keep her following a loan in the early 1980s (This loan was due to G-BOAC being returned to Fliton for wing repairs following a serious overheat).
Of the last two British aircraft, only G-BOAF resided at Filton under that registration, although only briefly following her acquisition by BA. Before that she was G-BFKX

What a crying shame it was that, after securing the block of letters G-BOAA to G-BOAG, the airline changed its name.

What total bilge; British Airways is a perfectly good name thank you very much.
As far as the lynch mob goes, if you'd only posted your points in a sensible and non-inflamitory manner (not to mention have interjected some facts now and then) you would I'm sure been a welcome contributer. The mob was of your own making sir.

Regards Dude

[Iron Duck]

mike-wsm

It fascinates me to look back on our past 'successes' and to see what white elephants they were in real terms when compared with those very few real success stories, where aircraft are produced in greater than 1000-off quantities. One of the key elements is humility, the ability to accept reality and adapt to it. The British national character is one of arrogance and an arrogant political system driving arrogant company management will never yield commercial success.

Several facts of post-war commercial aviation seem to be generally ignored. I wonder why?

1. The WW2 deal was that the USA would concentrate on transports whilst the UK produced combat aircraft. Whatever the final outcome of that war, several consequences were easily foreseeable:

a) that win or lose, the UK would be severely damaged and lose its empire, and with it its potential transport aircraft export market;
b) that Europe would also be severely damaged, and other European countries' empires would also collapse, and with them, potential European-made transport aircraft export markets;
c) that if the Nazis lost, the European aviation industries would remain fragmented, relying on small domestic markets;
d) that if the Nazis won, then all of Europe would be a domestic market for German transport aircraft, not American
e) but notwithstanding any of the above, a large and expanding domestic US market for US-built transports could be guaranteed.

So a move that appeared entirely sensible and plausible at the time, namely that the UK should concentrate on developing weapons to fight with, was always going to result in the postwar dominance of US transport aircraft.

2. The USA is the only major country not to have had a state-owned National Airline. Evan Pan-Am, the so-called "chosen instrument" of the State Department, was privately owned. Consequently, US airlines have been largely free to pursue purely commercial objectives, and US manufacturers to satisfy those airlines' equipment requirements.

3. The USA is the only Western country that has a domestic aircraft market large enough to sustain the profitable production of 1000+ of a type. The classic postwar US airliners would have sold in profitable numbers without a single foreign sale.

4. Why do nations have subsidised, state-owned national airlines? In order to carry out their Governments' political wishes. As we can see over and again, those political wishes very often conflicted with "business efficiency" as they resulted in those airlines having to operate unprofitable routes and, often, non-US equipment for political purposes. So it was that the VC-10, specified to operate UK "empire routes" and to operate from short and unimproved runways, was always likely to have higher seat-mile costs than the 707.

If Vickers hadn't had to comply with these requirements, would they have designed the VC-10 as they did? And was there ever going to be a 1000+ market for it in the post-war Marshall Plan world, in which the USA was making quite sure that Britain took its post-imperial "rightful place" in the global power structure? The USA's entry into WW2 was its bid for global domination. The Marshall Plan was the outcome. The USA always plays to win.

5. All of the successful postwar non-US types have been commercially successful because they were the first in their fields with no US-made equivalent and offered very significant performance improvements, operating cost reduction and passenger appeal when compared to existing US types: the Viscount, the Caravelle, the BAC 1-11. All achieved US sales. Even the Britannia did. The Comet and Concorde might well have joined this roster had events not turned against them. No other post-war non-US type ever stood a chance, commercially.

Edit: I should add the Fokker F27 to this list of successful non-US types, of course. As the first pressurised turboprop "DC-3 replacement" it was commercially successful for the same reasons that the others in this list were.

So were they white elephants? No. They carried out a strategic political function in maintaining the non-US aviation industrial base that gave rise to Airbus, a multinational consortium that eventually could command a potential non-US market to the extent that it could achieve 1000+ sales without needing sales to the USA, and thereby finally matching the potential of the US domestic market.

And, famously, passengers much preferred the Iron Duck to the 707. BOAC flew it more profitably on the North Atlantic than the 707.

Edit: The Iron Duck is, of course, the Vickers VC-10.

[Golf-Sierra]

How often do bits and pieces fall off planes?

Hello,

I was wondering just how common is it for various parts fall off planes? Understandobly this is vary likely in the event of a tail, wing, engine strike - usually (hopefully) the pilots would report this to ATC and someone would check that no debris is left before the next plane uses the runway.

Birdstrike can also lead to pieces falling off - but would the crew always be aware that a birstrike had occured? - Doubt it. Finally we have bits coming off of their own accord - well - unless it's something significant i.e. an engine or stabiliser - probably won't be noticed until someone inspects the runway?

So how often are various metal pieces of various sizes found on runways? Does this happen sufficiently often so that engineers and regulators should take them into account when designing and certifying aircraft? Planes are designed to handle birdstrikes - as these are likely to occur. Unlike trains however, they are not desgined to survive cow strikes ;-)

Did the designers of Concorde ever brainstorm what could possibly lead to a tyre failure? Were they able to draw on the experience gained from other types showing how failure of a cut tyre differs from that of an underinflated one?


Regards,

Golf-Sierra

[PBL]

Originally Posted by Golf Sierra

Did the designers of Concorde ever brainstorm what could possibly lead to a tyre failure? Were they able to draw on the experience gained from other types showing how failure of a cut tyre differs from that of an underinflated one?

Yes, and yes.

More details were given by M2Dude just a few posts back. Would you care to read his contribution?

PBL

[SLFinAZ]

The underlying issue here is the flawed presumptions...

A decision was made that the worst case scenario specific to a tire failure might result in a significant fuel leak (DC) but would not reach an order of magnitude capable of a catastrophic loss of the airplane. The simple fact is that this determination was wrong.

A prudent and reasonable person faced with the reality that tire failure would with certainty lead to ruptured fuel tanks and the resultant fuel leaks would look for a method to protect against the leaks.

The most significant underlying fact is that the technology existed to minimize the danger of a fuel leak specific to damage caused by tire failure. The issue here is not the cause of a specific failure but the stark reality that the airline chose not to maximize the safety of the aircraft for purely economic reasons by relying on a flawed analysis of the possibilities of catastrophic failure.

Air France had a legal and moral responsibility to operate the aircraft taking all reasonable measures to protect its customers. I have zero doubt that a jury presented with the facts available would find AF guilty of failing to act in a prudent and reasonable manner.

[PBL]

Speaking of flawed presumptions -

Originally Posted by SLFin AZ

I have zero doubt that a jury presented with the facts available would find AF guilty of failing to act in a prudent and reasonable manner.

I have considerable doubt. Mainly for the reason that, as far as I know in French law, as well as a number of other jurisdictions, "failing to act in a prudent and reasonable manner" is not a criminal offence.

Whatever the criminal offence may be of which you are trying to accuse Air France, if it is based on a claim (what you call "stark reality") that

Originally Posted by SLFinAZ

the airline chose not to maximize the safety of the aircraft for purely economic reasons by relying on a flawed analysis of the possibilities of catastrophic failure.

then I think a competente defence lawyer would shred it in a few minutes, by challenging you to provide any evidence that it was true, thus forcing your reply that you don't have any.

PBL

[infrequentflyer789]

Originally Posted by SLFinAZ

The underlying issue here is the flawed presumptions...

A decision was made that the worst case scenario specific to a tire failure might result in a significant fuel leak (DC) but would not reach an order of magnitude capable of a catastrophic loss of the airplane. The simple fact is that this determination was wrong.

No, the determination would have been that it was "Extremely improbable". The fact that it happened, once, doesn't necessarily disprove that.

However, since the way that it happened was through a damage mechanism not well known (if at all) in the civilian world, it is likely that, yes, the determination was wrong. It was, however, wrong due to the existence of an unknown phenomenon, not to to negligence or incompetence in making the determination.

A prudent and reasonable person faced with the reality that tire failure would with certainty lead to ruptured fuel tanks and the resultant fuel leaks would look for a method to protect against the leaks.

Tire failure does not lead to ruptured fuel tanks with anything like "certainty". Not even on Concorde.

Substitute "turbine disc failure" and now we're talking - maybe better that 30% probability of tank penetration, by hot fast moving deris, and subsequent fuel leak.

So, yourself being prudent and reasonable, which types do you fly on that have fuel tanks that are protected against leaks due to turbine disc impact ? I'd love to know what it's made of and how it gets off the ground.

The most significant underlying fact is that the technology existed to minimize the danger of a fuel leak specific to damage caused by tire failure.

The tires did not in fact exist - and they are the biggest improvement. The tank lining technology did not exist when the a/c was built and certified, and some reckon it has little benefit anyway.

Other a/c are now fitted with the new tire tech. Not so the tank linings.

Surely it would be "prudent and reasonable" to fit both to all types - so why not ? [clue: economics]. Are all operators as guilty as you think AF is ?

The issue here is not the cause of a specific failure but the stark reality that the airline chose not to maximize the safety of the aircraft for purely economic reasons by relying on a flawed analysis of the possibilities of catastrophic failure.

Aircraft safety is never maximised, there is always more that could be done, and that is for economic reasons. Adding stuff adds weight, reduces number of pax - economics.

Air France had a legal and moral responsibility to operate the aircraft taking all reasonable measures to protect its customers. I have zero doubt that a jury presented with the facts available would find AF guilty of failing to act in a prudent and reasonable manner.

AF have responsibility to operate the a/c according to its certification & other operational regs. They are not responsible for its certification.

AF (if they were involved in the risk calculations at all) evaluated the previous tire burst incidents, took remedial action based on the calculated risk based on what was known at the time. They were caught out by a freak accident and an unknown (to them) phenomenon.

If anyone's to blame for the risk calculation, blame the military guys for not disseminating knowledge of hydrodynamic ram.

[green granite]

The "flawed presumptions" are really only flawed with the benefit of hindsight, probably the vast majority of aircraft accidents would have been avoided if hindsight could have been applied before they happened. I suspect that almost everyone here has had something go wrong which, with hindsight, they could have avoided even if it was just burnt toast.

[bearfoil]

I like the US way, call me parochial.

".......The purpose is not to assign fault........."

bear

[Iron Duck]

bearfoil

I like the US way, call me parochial.

".......The purpose is not to assign fault........."

I don't think anyone here disputes that, per se: I think we all deplore the fact that in France it is necessary to hold a criminal trial to assign responsibility for damages and compensation, and that the threat of such a trial has a chilling effect on impartial accident investigation. We all wish that France had an inquest system.

But what is inescapable is that the accident happened in France, and as a consequence the investigation and subsequent actions are within and subject to French legal jurisdiction. Opinions ventured from the point of view of other legal jurisdictions are entirely irrelevant.

Edit: I should add, that includes opinions from a UK legal perspective. We have inquests and Coroner's Courts here. They're useful.

[SLFinAZ]

I am discussing civil not criminal liability here. however there is substantial case law specific to consumer safety where criminal sanctions were imposed for less serious breach of judgement.

IMO both a civil and criminal jury would view the motivation not to modify the fuel tanks as financially driven. Further they would view this decision as imprudent based on the statistical certainty of a fuel leak. The argument presented by the plaintiff/prosecution is the simple concept that given the statistical certainty of a fuel leak it is impossible to reach a conclusion that such a leak of unknown magnitude can be considered 100% safe.

Since a fire (however unlikely) is highly likely to cause a catastrophic event and loss of life a prudent person would seek to minimize the chance of a leak occurring. Had no leak occurred there would be no fire and the other damage would be insufficient to cause hull loss and resultant loss of life.

So the root cause of the accident is not the FOD but the negligence of the operator in taking appropriate safe guards specific to the potential for a known catastrophic event.

At the end of the day this was a business decision gone wrong and both a civil verdict and a criminal verdict of negligent homicide would be proper.

[Iron Duck]

SLFinAz

I am discussing civil not criminal liability here. however there is substantial case law specific to consumer safety where criminal sanctions were imposed for less serious breach of judgement.

Would that be French case law, perchance? And if not (see my post above), do you fancy canning it?

[PBL]

Originally Posted by SLFinAZ

I am discussing civil not criminal liability here

You used the word "guilty". That is a concept of criminal law, not of civil law.

You now say you are concerned with "liability". That is a concept of civil, not of criminal law. But you speak of "criminal liability", which I think is an inapplicable concept.

If we are going to have a half-way serious discussion about these matters, which I think are very serious indeed, and worth discussing, as I think you do, then there has to be some common agreement about the use of technical terms, whether of law or of aviation, otherwise we are all going to end up talking past each other.

Concerning liability, I think infrequentflyer789 has just said it. The regulator says the aircraft is airworthy; therefore Air France may fly it. The airline relies on the regulator to perform airworthiness assessments; it has no in-house expertise on that. Serious concerns about airworthiness are the responsibility of the regulator. And the regulator was in fact in court, charged!

DGAC was found not guilty and assigned zero part of the responsibility by the court (that itself seems to me a mixing-up of criminal- with civil-law concepts; it seems French trials of this nature serve both purposes). Whether that is just is something which we could profitably discuss in this thread.

PBL