Concorde 4590 [Archive] - PPRuNe Forums

booke23

6th Nov 2017, 20:32

Extract from the official report:

"In these extreme conditions (engines 1 and 2 producing no thrust), the combination of lateral and thrust asymmetry and the major thrust/drag imbalance, which could not be compensated for by a descent, led to a loss of control. This loss of control was probably accelerated by the structural damage caused by the fire.

In any event, even if all four engines had been operating, the serious damage caused by
the intensity of the fire to the structure of the wing and to some of the flight controls would have led to the rapid loss of the aircraft."

The evidence points to extreme low airspeed combined with two engines not producing thrust that caused the actual loss of control, but the fire would have caused it eventually.

At MTOW Concorde needs an absolute minimum of 206kts to climb away on 3 engines....263kts and gear up to climb away on 2 engines. They managed 211kts after engine 2 was shut down but at that point engine 1 stopped producing thrust and that was that.

The BEA calculated that had they performed a RTO at the time of realising something bad was happening, they would have gone off the end of the runway doing at least 74kts........atakacs was right when he said they were doomed as soon as the fire started.

rolling20

7th Nov 2017, 08:52

IIRC, debated on this site at the time, the FE shut down engines without the Captains authorisation?

atakacs

7th Nov 2017, 10:35

IIRC, debated on this site at the time, the FE shut down engines without the Captains authorisation?

Yes. But it didn't change the eventual outcome.

Once the tank was ruptured (for whatever reason, I am personally not fully convinced about that titanium piece) and the fuel ignited their fate was sealed.

booke23

7th Nov 2017, 10:55

IIRC, debated on this site at the time, the FE shut down engines without the Captains authorisation?

Yes, but just after he shut it down the captain called for the fire drill on engine 2, so it would have been shut down anyway.

I agree with atakacs.......the report focused too much on the titanium strip, and not enough on the missing spacer on the landing gear....causing the actual tyre that burst to shimmy around on the axle. The aircraft was also overweight by 0.7 - 1.2 tonnes, which it pretty shocking practice from a national carrier IMHO.

atakacs I'd be interested to hear your doubts on the titanium piece.

MATELO

7th Nov 2017, 15:34

It's easy to find, but if you want to save yourself a ton of reading...

..through no fault of their own the crew took an uncontained fire into the air with the inevitable consequences...

/thread

Not quite the case..... I will leave it to the expert to explain..

https://www.youtube.com/watch?v=fqOcYhzWUZY

DownWest

7th Nov 2017, 18:40

Not quite the case..... I will leave it to the expert to explain..

https://www.youtube.com/watch?v=fqOcYhzWUZY

I had this explained to me by a friend who was a BA pilot and lectured on safety for them. This was around 16yrs ago and he detailed all the points in the vid, except the part about the transfer of fuel from the rear tank to the ruptured one. The point where the FE shut off no.2, was the key to the final result. He had access to the CVR and was amazed that happened. The crew had a big part in the accident, along with the maintainance leaving out the spacer in the UC. Lots of careful lining up of holes in the cheese.
DW

Mike Flynn

7th Nov 2017, 21:21

I was working as a global tv news producer at Reuters HQ in London the day of the accident.

Reuters bought this famous footage for £1200.

https://m.youtube.com/watch?v=3rPz6hwDgh0

paradoxbox

8th Nov 2017, 06:35

if the fact that the captain overloaded the aircraft and took off with a tailwind is true, it would seem that was one of the greatest factors in explaining why the aircraft crashed.

the aircraft was overloaded by something like 3 tons under the captain's authority with additional bags and fuel, and was taking off with a tailwind, presumably without recalculating the v speeds for that runway. the fire and the FE shutting down the engine was the icing on the cake.

other contributing factors included the fire, which could have been avoided if the airlines had followed recommendations by safety organizations to reinforce the tanks near the landing gear, as this was not the first time the concorde had an explosive gear failure incident leading to wing damage. in fact it had happened quite a few times throughout the 70's and 80's including several fairly severe wing damage incidents. the airlines elected to ignore the report and operate the aircraft as they were for almost a decade before the final accident. if the tank had not been full it probably would not have exploded as there would have been a small yet important gap between the fuel surface and the tank skin, allowing the empty space to absorb some of the shockwave that resulted from debris hitting the bottom of the wing.

a lot of things contributed to that accident. the dc-10 part lying on the runway was a big catalyst but certainly not the only thing that caused the end result. the whole takeoff was a mess of bad decision making.

atakacs

8th Nov 2017, 11:29

if the fact that the captain overloaded the aircraft and took off with a tailwind is true, it would seem that was one of the greatest factors in explaining why the aircraft crashed.

Not sure to follow you train of thought. Do you mean that if the aircraft was 1.5t lighter it would have accelerated faster, thus not hitting the titanium strip ?

This accident has been discussed ad nauseum at the time and I think there is pretty much a consensus that once the massive leak ignited it was game over: they couldn't stop, they couldn't fly.

As for engine 2 shut down I agree that the lack of communication is surprising and didn't help, although it was the "right" thing to do given the circumstances. They had clear engine fire alarms, engine surge indication and ATC screaming the same. How could they guess that it was not actually an engine fire (which no one suspected until much latter) ? But in any case it didn't change the eventual outcome - except maybe for the victims on the ground.

atakacs I'd be interested to hear your doubts on the titanium piece.

I am not privy to any "inside" information but I muss say that despite knowing the huge loads on Concorde tires at takeoff and the simulation by the BEA I have a hard time to believe that strip really destroyed the tire. To be honest, very, very convenient. And even if it did, the missing spacer on the landing gear was pretty much overlooked in the report whereas it was designed to precisely help in such circumstances. Overall I would say the Concorde operation at AF did not look as professional as it should in 2000.

MATELO

8th Nov 2017, 12:20

As for engine 2 shut down I agree that the lack of communication is surprising and didn't help, although it was the "right" thing to do given the circumstances. They had clear engine fire alarms, engine surge indication and ATC screaming the same. How could they guess that it was not actually an engine fire (which no one suspected until much latter) ? But in any case it didn't change the eventual outcome - except maybe for the victims on the ground.

Given the video I posted, John Hutchinson try googling him, pretty much the expert on everything that is concorde, says this is categorically the wrong thing to have done.

atakacs

8th Nov 2017, 12:58

Given the video I posted, John Hutchinson try googling him, pretty much the expert on everything that is concorde, says this is categorically the wrong thing to have done.

And what other course of action was possible? Deploy ejection seats? Fire the JATO rockets?
I shall listen to his video but given the information they were presented with I will not fault them on that point. In any case pretty academic and assuredly irelavant. Even if André Turcat would resurrect and come to tell me otherwise I would not believe that flight could be saved.

Buster15

8th Nov 2017, 13:58

I am not privy to any "inside" information but I muss say that despite knowing the huge loads on Concorde tires at takeoff and the simulation by the BEA I have a hard time to believe that strip really destroyed the tire. To be honest, very, very convenient. And even if it did, the missing spacer on the landing gear was pretty much overlooked in the report whereas it was designed to precisely help in such circumstances. Overall I would say the Concorde operation at AF did not look as professional as it should in 2000.[/QUOTE].

Don't forget that AF had been using re-treaded tyres which BA had not.
It was believed that the strip cut across the tyre and at that speed in excess of 4kg of rubber hit the underside of the wing exactly at a point of a thick and thinner section causing the rupture.
The missing wheel spacer was causing the aircraft to track off the runway c/l. This meant that additional rudder was needed.
The investigation was extremely comprehensive.

MATELO

8th Nov 2017, 15:55

And what other course of action was possible? Deploy ejection seats? Fire the JATO rockets?
I shall listen to his video but given the information they were presented with I will not fault them on that point. In any case pretty academic and assuredly irelavant. Even if André Turcat would resurrect and come to tell me otherwise I would not believe that flight could be saved.

The video tells you the course of action to take.

atakacs

8th Nov 2017, 16:45

Well I have watched the video (great material btw, highly recommended for anyone interested in this tragic accident). I am in full agreement with Capt. Hutchinson that there were many contributing factors and that the "infamous" titanium strip was just a piece of the puzzle. I would go as far a to say that the BEA report, however comprehensive, is definitely not weighting all those factors adequately. And I would venture to say that they were both very unlucky and very lucky (they could have very well collided with the 747).

I also agree that the actions of the crew, especially pre-takeoff but also during the emergency, were subpar and not conforming to established procedures.

Yet, given the circumstances and the law of physics, and without the benefit of hindsight, there is zero chance that they would have walked away from this one. The only better outcome I can imagine is a more or less controlled crash landing in a field or on the Bourget runway, thus sparing the lives of the people in the hotel. Which, admittedly, is not negligible...

Chronus

8th Nov 2017, 19:16

booke23

8th Nov 2017, 20:09

The action that caused the crash was the engine shut down. Had this action not been taken, whether it would still have crashed has not and never will be resolved. In that respect the speculation lies on whether the decision would have remained to make for Le Bourget and made a successful landing there.

But engine 1 surged and flamed out due to ingestion of hot gasses from the fire shortly after engine 2 was shut down......I'd say it was certain that engine 2 would have flamed out along with engine 1 if it had still been running.

In the circumstances, and in hindsight (the crew could never have known this at the time) their best chance was an RTO. Once they got in the air, with engine 2 shut down as soon as their speed dropped below 205kts (gear down 3 engine Vzrc) they were going down whatever.........their only chance would have been a forced landing in whatever clear area they could see straight ahead. I don't think either option would have ended well.

atakacs I agree the titanium strip was very convenient for the investigation. Personally I think the BEA report was a bit of a whitewash. It should have investigated the effect of the missing spacer much more thoroughly. It also should have investigated human factors and the culture within the Air France Concorde operation that allowed the aircraft to depart overweight.

Concours77

9th Nov 2017, 13:59

atakacs: "atakacs I agree the titanium strip was very convenient for the investigation. Personally I think the BEA report was a bit of a whitewash. It should have investigated the effect of the missing spacer much more thoroughly. It also should have investigated human factors and the culture within the Air France Concorde operation that allowed the aircraft to depart overweight."

If the gear was vibrating badly, would an RTO have been initiated? The loss of #2 doomed the aircraft, regardless whether done by engineer or flame out. I agree the causes were plentiful, and the Titanium strip in my opinion was exaggerated.

booke23

9th Nov 2017, 22:22

If the gear was vibrating badly, would an RTO have been initiated?

If it was vibrating badly, then yes. But in this case it wasn't vibrating....at least not enough to be heard on the CVR.

The missing spacer allowed the tyre to track 3 degrees right or left of centre. My feeling is that the tyre would have been tracking off centre...ie scrubbing sideways slightly. When it hit the Titanium strip at 175kts, did the sideways scrubbing cause the tyre to tear more dramatically? Would it have burst at all if it had been tracking straight when it hit the strip or at least have failed less catastrophically? We'll never know but will always wonder.

Tay Cough

9th Nov 2017, 22:51

If the gear was vibrating badly, would an RTO have been initiated?

Never having flown Concorde (sadly), this is an educated guess based on 15000 heavy jet hours (Boeing and Bus).

No, probably. A vibration with no other indications would not normally warrant a stop. My current type requires a (low speed) stop for a tyre failure but otherwise an indication on a gauge is generally required. Having said that, there’s nothing to prevent a stop call for any reason from the commander if he sees fit.

blind pew

10th Nov 2017, 05:21

Loss of control was purely from flying too slow.
Co pilot was calling “speed” which indicated that he thought the captain had the wrong priority.
Captain was flying a pitch attitude that meant speed was decreasing.
Centre of lift moves forward until elevons cannot stop the pitch up and the aircraft “flips”.
Had two delta model aircraft that did the same...both unstable in pitch at low speed.
If he had flown as low as possible he would have delayed the crash but it was probably inevitable from the time he decided to prematurely get into the air but at least he would have crashed in control.

hoss183

10th Nov 2017, 13:10

Probably best for you to read the official investigation report carried out by the French BEA. You can easily access it by Internet search.

:rolleyes: Oh really? Because the BEA included all information and has a reputation for being unbiased... lol

paradoxbox

21st Nov 2017, 02:54

Not sure to follow you train of thought. Do you mean that if the aircraft was 1.5t lighter it would have accelerated faster, thus not hitting the titanium strip ?

My assumption (Knowing assumptions are dangerous) is that the crew did one of two things, or perhaps both.

1) The aircraft was overweight. This caused a number of speed related problems.
They did not recalculate takeoff speeds. According to various interviews and info regarding the accident, the captain took on something like 1 ton of extra fuel in addition to the extra baggage. They had planned for extended taxi time either due to traffic or for positioning on a different runway.

However, they did not end up burning that fuel before attempting the takeoff. The assumption is that they tried to take off at speeds calculated for a lower fuel AND baggage load.

2) The aircraft took off with a tailwind without recalculating the v-speeds AND without factoring in the tailwind component as it would affect the aircraft at the higher takeoff weight.

So one can surmise that they not only had some kind of gear problem during the takeoff roll that may have prevented them from accelerating at the normal speed, and they may have had steering difficulty while on the roll, but they also rotated far too soon due to not recalculating, maybe as much as 10 knots under the correct speed, plus the fact that they were overweight, with a tailwind not helping things, and then the engines were shut down, all while being on fire and with possible damage or debris causing drag all over one side of the aircraft.
The extra tailwind component could have been the difference between staying up and going down. They must have been below their engine out safety speed. Had they calculated correctly, the aircraft -may- have been salvageable if the fire did not consume the aircraft in the air. Had they lifted off with 5-10 knots more speed as would have been proper, they would have made their engine out speed and thus could have flown out of the death-drag curve, in theory.

In a delta wing aircraft excessively early rotation with insufficient thrust to lower the AoA results in something called aerobraking. Among other things it's used to slow down spacecraft reentering the atmosphere. It is remarkably effective at slowing down airplanes. On the runway it kills acceleration, in the air it turns you into a flying brick.

I feel bad for them but there were a lot of amateur mistakes made in allowing the aircraft to even take off in that condition. There are a million youtube videos of aircraft ranging from cessna to airbus showing the disastrous or near disastrous results of trying to take off while overweight and in bad conditions i.e. density altitude stuff. Tail strikes being the best case scenario, crashing into trees or water at the end of the runway being the more common scenario.

These guys didn't have a chance past V1 IMO. Too many bad choices.

Dr Jekyll

21st Nov 2017, 12:42

I understood that they lifted off when they did to avoid running off the side of the runway and potentially into the side of a stationary 747.

paradoxbox

30th Nov 2017, 10:22

Which begs the question, if they had lost good ground steering why didn't they chop the throttles while below 80 or V1. Of course everything is 20/20 in hindsight but.. One does have to wonder what the FE was doing on the takeoff roll. I wonder what the gear temp gauges were reading at 80 knots.

I dunno. There are too many things that went wrong on that flight. We can only hope that their mistakes help others to avoid repeating them. Unfortunately the official crash investigations seem to have covered up a lot of important information for whatever reason, so a lot of valuable info may be lost and we can only go by speculation, rumor and anecdotes from other Concorde pilots and people at the scene.

G0ULI

30th Nov 2017, 12:19

What this accident served to demonstrate was that a lot of sloppy practices had crept into the system, in maintenance, in flying the aircraft, and in not adhering strictly to weight and balance considerations.

The fact that the aircraft coped admirably with all these issues for many years without a mishap demonstrates that the aircraft was operating well within its limits when everything was done by the book. It was also capable of operating quite a bit beyond the book figures when required. The aircraft acquired something of a reputation for being able to handle anything that was thrown at it.

The conclusion has to be that many crews undertook flights under similar circumstances and repeatedly got away with it. Because of that, this was an accident that was bound to happen sooner or later. The Titanium strip was just an initiator in a chain of events that stretched from well before the aircraft boarded passengers to the decision not to reject take off. Nobody involved in the chain of events comes out squeaky clean.

booke23

30th Nov 2017, 14:35

Which begs the question, if they had lost good ground steering why didn't they chop the throttles while below 80 or V1.

Although the missing tyre spacer was causing the wheel to shimmy, it didn't cause much steering difficulty.

The directional control problems only occurred after they hit the titanium strip, caused by the reduction of thrust on engines 1 and 2 and the drag from the burst tyre. The tyre burst at 175kts......way beyond V1. That being said, in hindsight a RTO with high speed runway excursion would probably have been their best (albeit small) chance.

As to sloppy practices.....If they were flying Concorde like that you can guarantee they were flying other aircraft like it too. The report didn't probe the culture within the airline that allowed the sloppy practices to creep in. I'd like to hope Air France did probe and develop culture/training to eradicate it.

Benny B

8th Jan 2018, 13:03

Hi All

Just recently I watched a documentary that stated that the Flight Engineer shut the engine (on fire) down without any order to do so.

The thinking behind not shutting down an engine on fire at that critical T/O juncture that was that even an engine on fire is producing some thrust.....

Also the missing spacer on the left hand main gear meant that the Concorde veered to the left obviously and that to miss the Air France 747 waiting to cross the live runway, they rotated at a much lower speed than would have been the case normally.

Also mentioned was that under normal circumstances all Concorde flight crew only fuelled up to around 82/83% of maximum to allow for some expansion space in the tanks. The Captain on the day did recognise that he was over loaded and insisted that full (as in full) fuel was added thus leaving no spare expansion space in the tanks. (Btw I know that seems like a contradiction)

Once that piece of rubber hit the underside of the left wing, the shock wave had nowhere to go and then we see the fuel leak and subsequent fire caused by a spark from the main gear electrics.

Shaggy Sheep Driver

10th Jan 2018, 15:06

The other reason you don't shut a running (or partially running) engine down like that, even if it's displaying a fire warning, is that you'll lose the services it provides in the form of electrical power and hydraulics.

On Concorde the undercarriage is operated by the 'green' hydraulic system. The 'Green' system is driven by pumps on engines 1 & 2. Shutting down No.2 when No.1 had failed meant they could not raise the gear, greatly adding to the drag.

atakacs

10th Jan 2018, 19:00

A very valid point.

But I'm still of the opinion that once the tank ruptured the way it did and the fuel ignited this flight was doomed no matter what. The only better outcome they could have possibly achieved is to avoid the hotel (which, I guess, is already worth this discussion).

booke23

10th Jan 2018, 21:27

On Concorde the undercarriage is operated by the 'green' hydraulic system. The 'Green' system is driven by pumps on engines 1 & 2. Shutting down No.2 when No.1 had failed meant they could not raise the gear, greatly adding to the drag.

The gear wouldn't retract due to an undetermined fault with the left gear.....either damage to wiring around the left gear or damage to the gear door, the investigation couldn't establish exactly what.

But they established the Green hydraulic system was functional when the gear lever was selected up and although it probably lost pressure at some later point in the flight, it couldn't be determined exactly when.

Green hydraulics or not, the gear was going nowhere.

B Fraser

28th Jan 2018, 13:05

I attended a lecture on the accident which was given by a former BA Concorde driver (Mr Cough knows him and may well have attended the same evening presentation, it was many years ago). IIRC, AF overfilled the fuel tanks. There was a switch that limited the tanks to about 97% occupancy however the switch was overridden and they squeezed in as much as they could. As a result, there was no air gap above the fuel and the slab of rubber hitting the tank set up a shock wave that blew out a panel further aft. Had the fuelling complied with the manual, would the tank have remained intact ? It's probably impossible to say for sure.

Are there any tech people who can comment on the tank limit and why such a limit was imposed in the operating handbook ? Are there similar limits for other aircraft and again, why are those limits there ?

Buster15

28th Jan 2018, 13:30

:rolleyes: Oh really? Because the BEA included all information and has a reputation for being unbiased... lol

No doubt you missed the previous post to which this response was submitted.
Whether you agree or disagree, the investigation was extremely comprehensive and covered all the relevant findings.
Regarding a number of points relating to the titanium strip being a convenient finding, this is totally incorrect. That strip was clearly the prime cause. Without that the tyre would not have disintegrated as it did. Yes there had been a number of previous tyre failures on t/o but the mass of the rubber that was released was larger and that as we now know was the cause of the damage to the wing underside resulting in the massive fuel loss.

Shaggy Sheep Driver

28th Jan 2018, 17:07

atakacs

28th Jan 2018, 17:12

Several factors HAD to come together for the accident to happen. The metal strip is no more 'prime' than any of the others.

Well that's how accidents happen. In almost all cases it's a chain of unrelated events out of which it is difficult to pinpoint a unique cause. The only question here is how to weight them. I would agree that the BEA report might put too much emphasis on the titanium strip...

Buster15

28th Jan 2018, 17:21

The metal strip would have been of no consequence (would not have been run over) if the missing spacer hadn't steered the aeroplane to the left, and eventually off the side of the runway breaking edge lights.

The tank would not have burst had it not been overfilled.

Several factors HAD to come together for the accident to happen. The metal strip is no more 'prime' than any of the others.

So what caused the tyre to fail in the way that it did then?
The missing spacer was a secondary cause but as you say there were a number of contributary factors. However, none would have hazarded the flight had the tyre not failed.

Shaggy Sheep Driver

28th Jan 2018, 21:11

So what caused the tyre to fail in the way that it did then?
The missing spacer was a secondary cause but as you say there were a number of contributary factors. However, none would have hazarded the flight had the tyre not failed.

Or had the fuel tanks not been overfilled.

Or the No.1 engine had not ingested a runway light or two.

Or the aircraft hadn't been rotated well below normal speed due that left tracking off the runway....

The latter two of these only played their part because the missing spacer sent the aircraft off to the left. Where it met the metal strip.

So if you want to nominate a 'prime cause' I'd point to the missing spacer.

But I'm happy not to try to pin this on any 'prime cause', but to accept that as in almost every aircraft accident, it's the combination of all of them that resulted in the tragic loss of the aircraft, those on board, and those on the ground.

mustafagander

29th Jan 2018, 09:08

Buster15

29th Jan 2018, 14:31

As always there are many factors leading to an accident. Remove any one and the accident is likely to be averted. However any reasonable review of the known facts would point to the missing spacer as the initiating factor. Fit the spacer and the aircraft tracks the runway c/l without the tyre drag and without hitting the notorious titanium bit. Then there is a better than even chance that rotation is about normal speed and we fly away.

Read the investigation report have you?.
If you have then you will see what the conclusions were. Furthermore, both AF and BA changed the tyre construction to reduce the impact of a failure and fitted Kevlar Liners to the fuel tanks.
Why would they go to that expense in order to resume operations if it was as simple as ensuring correct maintenance.

Shaggy Sheep Driver

29th Jan 2018, 17:07

Buster15

29th Jan 2018, 18:37

Buster, you are moving your goal posts. You claimed the metal strip was the prime cause. I and others disagree, with the spacer (if anything) being the prime cause. Actually I'm happy not attributing a 'prime cause' as I said earlier. It took ALL the factors coming together to result in the accident. So ALL the factors that caused that accident have to be addressed, including the tyres.

No I am not. For your information I was involved in the return to service programme following the crash and knowing what I know I completely agree with the BEA investigation and its findings.
It is quite clear that the titanium strip, having been run over at high speed was the prime cause of the catastrophic tyre failure. Had the tyre not failed IN THE WAY THAT IT DID then the other anomalies could have been managed by the aircrew.
It is really important to remember that 113 people died as a result and therefore we ought to respect the formal investigation findings, bearing in mind that the evidence was provided by subject matter experts.

Shaggy Sheep Driver

29th Jan 2018, 21:18

No I am not. For your information I was involved in the return to service programme following the crash and knowing what I know I completely agree with the BEA investigation and its findings.
It is quite clear that the titanium strip, having been run over at high speed was the prime cause of the catastrophic tyre failure. Had the tyre not failed IN THE WAY THAT IT DID then the other anomalies could have been managed by the aircrew.

We've covered this. You are going round in circles.

It is really important to remember that 113 people died as a result and therefore we ought to respect the formal investigation findings, bearing in mind that the evidence was provided by subject matter experts.

I've no idea what you are trying to say with this. What has the tragic loss of life got to do with trying to put the blame on a bit of runway debris? Are you an apologist for Air France who shamefully tried to pin those 113 deaths entirely on a maintenance engineer in America?

Quite rightly the courts threw that one out.

The bottom line is those 113 lives are down to Air France for shoddy maintenance and even shoddier operating of a magnificent aeroplane.

I think this conversation has more than run its course.

India Four Two

29th Jan 2018, 23:10

I'll divert the conversation and go off "at an angle" as it were.

How does a missing spacer on an axle, that is perpendicular to the direction of motion, cause the wheels to track incorrectly?

DownWest

30th Jan 2018, 07:48

The spacer held apart two collars that kept the axle in line. Its absence allowed the collars to drift to the same side and leave the axle unsupported, in this case, on the left side.

mustafagander

30th Jan 2018, 09:00

India 42, The guts of it is that the missing spacer enabled the wheels to migrate from designed positions and led to a strong left drag on the left truck by their twisting a bit left. This cost acceleration due to wheels not tracking along the longitudinal axis of the a/c and hence scrubbing a bit sideways. There was a drag induced by the necessity to steer right as well. This all cost energy and reduced performance of an a/c already over limits.
If the a/c had tracked the runway c/l there would likely have been no incident notwithstanding the huge performance discrepancies.

Shaggy Sheep Driver

30th Jan 2018, 09:27

Not only did the missing spacer, through allowing the axles to mis-track, steer the aeroplane left, but the resultant scrubbing of the tyres which were not parallel with the aircraft's direction of travel since the wheels were mis-aligned, caused extra stress and heat to the tyres which would contribute to their failure.

rog747

30th Jan 2018, 12:51

this accident from what we know now had NO primary cause or prime factor

it was a growing chain on the day of unconnected events and omissions errors complacency and perhaps even some arrogance

no one has mentioned that the runway was not swept for the concorde's departure which afaik was standard at CDG pre for all take offs -could you say then that was the root cause that started it all? no - course not -as other factors had already slotted into place with others lining up

one simply cannot say here that one primary item alone lead to the downing of 4590

one of the ''Titanic's'' of air travel accidents - another being KLM Pan Am Tenerife 1977 and THY DC-10

Bergerie1

30th Jan 2018, 12:59

And JAL 123

Shaggy Sheep Driver

30th Jan 2018, 13:23

this accident from what we know now had NO primary cause or prime factor

Exactly. Like most it was a coming together of many factors - classic lining up of the holes in the cheese. The sad part is as you say, complacency and perhaps arrogance played a major role, to which I'd add a certain amount of attempted blame-deflection by AF after the tragedy.

Despicable.

rog747

30th Jan 2018, 13:26

Exactly. Like most it was a coming together of many factors - classic lining up of the holes in the cheese. The sad part is as you say, complacency and perhaps arrogance played a major role, to which I'd add a certain amount of attempted blame-deflection by AF after the tragedy.

Despicable.

quite - i wish to add again as mentioned in my post ---
no one has mentioned that the runway was not swept for the concorde's departure which afaik was standard at CDG pre for all take offs - could you say then that was the root cause that started it all?
no - course not - as other factors had already slotted into place with others lining up so that theory throws Busters argument right out of the water - no disrespect intended but one has to say

booke23

30th Jan 2018, 16:39

Buster15

30th Jan 2018, 17:16

There is quite a bit of mis-information on this thread.

Extracts from the BEA report:-

"The wheels were manufactured by Dunlop, and the tyres used by Air France were
manufactured by Goodyear in the United States. No retread tyres have been used since 1996."

Page 37 of the report has a diagram showing the ground track of the aircraft on the runway. This data is derived from the ground radar and as such is very accurate. It clearly shows the aircraft was tracking the centre line of the runway until after it had hit the strip. In other words, the missing spacer did not cause the aircraft to veer left....loss of thrust on the left side was the cause.

I think the report could have been more comprehensive. As already mentioned there was no investigation into the affect of the misaligned tyre running over the strip. Did that misalignment cause the tyre to fail more catastrophically than it otherwise would? We'll never know.

Thank you brooke. That was why I had referred people to the BEA report and its findings.
I had mentioned the tyre construction because as you point out AF had used retreads in the past. During the investigation testing was carried out to demonstrate the effect of failures of various types of tyre construction.
It is correct to say that the French preferred to focus on the tyres while the UK felt that (because of the number of previous tyre failures) that fitting the Kevlar Liners to the fuel tanks would improve safety. BA were very keen to restore Concorde airworthiness as their operations had been quite profitable.
Hope this clarifies the situation.

B Fraser

31st Jan 2018, 07:01

I remember reading that a number of credible witnesses who were very familiar with the airport layout commenting that there were problems well before the point at which Concorde was said to have run over the strip. IIRC, they included firemen who would not be prone to making errors and the comments related to smoke. This would be consistent with the tyres on the misaligned axle scrubbing on the tarmac. If the aircraft was still on the centreline then it begs the question of how much rudder / nose wheel input was being applied at that time.

I would disagree that there was no single factor involved. It was a multitude of failures to follow SOPs. I post here under my own name so please forgive me for calling a spade a spade but the elephant in the room here would appear to be operating culture. I would be happy to be proven wrong so go gently chaps.

Shaggy Sheep Driver

31st Jan 2018, 09:04

B Fraser - I totally agree.

booke23

31st Jan 2018, 12:37

It was a multitude of failures to follow SOPs. I post here under my own name so please forgive me for calling a spade a spade but the elephant in the room here would appear to be operating culture.

I agree to a large extent. I was disappointed that the report did not probe the culture within the airline. There were also human factors lessons to be learnt
with regards to aircraft maintenance.....reading between the lines in the report, that undercarriage was reassembled incorrectly on a night shift (not the first or last time a serious maintenance error happened in the middle of the night).

However you have to ask.......if the aircraft was at MTOW (not over it), took off with the spacer in place the No 2 engine wasn't shut down.....would the outcome have been different? (btw the tank that ruptured wasn't overfilled according to the report)

Well the tyre would almost certainly still have burst. If it shed 4.5kg of rubber up against the tank it would still have ruptured and caught fire. If engine 2 hadn't been shut down it would have flamed out anyway as engine 1 did. So they may have flown a little bit further but the outcome would have been the same.

B Fraser

31st Jan 2018, 13:13

The chap who gave the presentation I attended mentioned that some of the runway lighting debris was ingested by the #1 engine. I'm not sure how he knew this but as he was a BA skipper, I trust his account. Perhaps if the spacer had been fitted and the strip of titanium was positioned so it still hit the tyre, would the aircraft have veered by the same degree and not hit the edge lighting ? We will never know.

Buster15

31st Jan 2018, 16:00

However you have to ask.......if the aircraft was at MTOW (not over it), took off with the spacer in place the No 2 engine wasn't shut down.....would the outcome have been different? (btw the tank that ruptured wasn't overfilled according to the report)

Well the tyre would almost certainly still have burst. If it shed 4.5kg of rubber up against the tank it would still have ruptured and caught fire. If engine 2 hadn't been shut down it would have flamed out anyway as engine 1 did. So they may have flown a little bit further but the outcome would have been the same.

They were also quite unlucky in that the tyre debris was thrown up at speed and impacted the underside of the wing very close to a junction between a thicker and thinner (machined) section. The fuel pressure pulse then fractured the skin at that junction. Had it impacted at a slightly different location it is possible that the wing skin may not have failed OR lead to a smaller leak.

All this discussion about the crash must not detract from the stunningly brilliant technical achievement that was Concorde.

booke23

31st Jan 2018, 16:45

You are quite right about the tyre debris.......To cause tank rupture it probably had to hit the tank within quite a small range of angles......a more glancing blow would not have had the energy to cause major damage. It could have flown off the tyre at any angle, yet it happened to impact the wing square on and rupture it.

If you tried to replicate it in a lab, you'd probably have to do it a couple of dozen times before you got a piece to hit the wing and cause damage. Of course these type of freak happenings are often the root of many disasters.

All this discussion about the crash must not detract from the stunningly brilliant technical achievement that was Concorde.

Absolutely.....in my view, one of the best aircraft mankind has ever made. I still can't quite believe one crashed.

B Fraser

31st Jan 2018, 19:10

They were also quite unlucky in that the tyre debris was thrown up at speed and impacted the underside of the wing very close to a junction between a thicker and thinner (machined) section. The fuel pressure pulse then fractured the skin at that junction.

I think it is well documented that the tank did not rupture at that point. The absence of an air gap in the tank due to intentional overfilling caused conditions where a shock wave could pass through the fuel, blowing out a hole far from the point of debris impact. Another violation of a SOP, another hole in the Swiss cheese.

Shaggy Sheep Driver

31st Jan 2018, 20:58

Quite so, The rupture of the tank was FROM THE INSIDE OUT, not the outside in, by an overpressure caused by there being insufficient gap of compressible air at the top of the tank to absorb that overpressure in the incomprehensible fuel, the initial cause of which was a big bit of tyre hitting (but not puncturing) the underside of the tank.

Feathers McGraw

1st Feb 2018, 11:57

It's also worth pointing out that according to John Hutchinson fuel was being transferred forward from the rear fuselage tank during the take off roll, this is apparently not permitted. The reason was that the CoG was too far aft, not helped by that extra baggage. In addition because rearwards transfer is needed for acceleration with centre of lift movement it was important to get the fuel out of the fuselage tank for that reason too otherwise there would be no space to move fuel back once climbing towards Mach 1.

Something not often mentioned is that the longer CDG-JFK route imposed a fuel penalty on Air France Concordes and perhaps that could have led to a culture of adding extra fuel which became a habit and was not questioned.

flyboyike

1st Feb 2018, 22:49

The aircraft was also overweight by 0.7 - 1.2 tonnes, which it pretty shocking practice from a national carrier IMHO.

You're kidding, right?

booke23

2nd Feb 2018, 15:15

You're kidding, right?

Afraid not. 19 bags were put on the aircraft without appearing on the load sheet. And of the 2 tonnes of taxi fuel loaded, only half was used before take off. The investigation couldn't determine the exact overweight figure, but it was somewhere in the 0.7 - 1.2 tonne range........probably closer to the 1.2 tonne figure, given the nature of the pax (joining an extended duration cruise).

B Fraser

2nd Feb 2018, 16:29

Those bags are said to have been loaded in the rear hold which didn't help the CoG. A further 10 bags were left behind. The status of each bag is not immediately clear however the accepted number of bags loaded that were not on the load sheet is 19.

The document at the link below shows that right rudder was being applied progressively during the take off run. The key data is about 1/3 down the page showing larger lateral accelerations from 100kts onwards. This could be consistent with the hypothesis that the missing spacer was affecting performance prior to the tyre burst event and reliable witness statements that smoke was seen far earlier than the fire. I can't see any reference to the spacer in the report but I have not read it in great detail

https://www.bea.aero/docspa/2000/f-sc000725pa/htm/f-sc000725pa.htm

Buster15

2nd Feb 2018, 18:40

The document at the link below shows that right rudder was being applied progressively during the take off run. The key data is about 1/3 down the page showing larger lateral accelerations from 100kts onwards. This could be consistent with the hypothesis that the missing spacer was affecting performance prior to the tyre burst event and reliable witness statements that smoke was seen far earlier than the fire. I can't see any reference to the spacer in the report but I have not read it in great detail

https://www.bea.aero/docspa/2000/f-sc000725pa/htm/f-sc000725pa.htm

Fraser. Page 155 of the BEA Report states that (words to the effect) the analysis carried out shows that the absence of the Spacer had no affect on the aircraft crash.

B Fraser

3rd Feb 2018, 06:54

Thanks Buster, I was looking for references using keywords but can't find any in the preliminary report. The subject is as you say covered in the final report from P.148 onwards at https://www.bea.aero/uploads/tx_elydbrapports/f-sc000725a.pdf

Concours77

3rd Feb 2018, 14:52

Is the chronic lateral and increasing port side trend charged to a specific finding?

It seems to me that if FOD is portrayed as the cause, its location on the runway has much to do with this left drift. Absent leftward Bias, does the Titanium strip come into play? At all?

Shaggy Sheep Driver

3rd Feb 2018, 17:23

Knowing how - ahem - 'unbiased' the French are when it comes to attributing blame (like their despicable attempt to blame the entire tragedy on a maintenance engineer at Continental, which the courts rightly threw out) I prefer BA Concorde Captain Hutchinson's take on the spacer issue and the evidence of unbiased witnesses to which the report gives little heed, above the complete dismissal the BEA report gives it.

That is simply not tenable IMO.

pulse1

5th Feb 2018, 08:31

I prefer BA Concorde Captain Hutchinson's take on the spacer issue and the evidence of unbiased witnesses to which the report gives little heed, above the complete dismissal the BEA report gives it.

According to the series of lectures given by the ex BA Concorde flight engineer, one of the best witnesses was the captain of Mitterrand's Airbus which was holding to cross the runway. Apparently he witnessed that there were signs of fire before the Concorde reached the metal strip. His testimony was not included.

B Fraser

5th Feb 2018, 12:17

The same goes for the airport fireman who noted smoke coming from somewhere consistent with the bogie.

booke23

5th Feb 2018, 14:45

Apparently he witnessed that there were signs of fire before the Concorde reached the metal strip.

This thread is in danger of descending into a farce of conspiracy theories. (if it hasn't already).

Buster15

5th Feb 2018, 15:56

This thread is in danger of descending into a farce of conspiracy theories. (if it hasn't already).

Agreed. Some people seem to believe that because the crash investigation was carried out by the French BEA that the report was biased in favour of AF and ignored vital information. Technical information was requested from and supplied by a range of specialists including Airbus UK and RR.
Quite how anybody watching the takeoff could accurately know and remember where the strip was on the runway when the aircraft was travelling at speed is open to question.

Shaggy Sheep Driver

5th Feb 2018, 17:02

Agreed. Some people seem to believe that because the crash investigation was carried out by the French BEA that the report was biased in favour of AF and ignored vital information.

It was and apparently it did. Is it a 'conspiracy theory' that following the publication of the BEA report AF tried to lay the entire blame at the door of a Continental Airlines maintenance engineer, a despicable try-on thrown out by the courts?

You only have to look at how that Concorde was being operated to understand the serious inadequacies of that airline. And of course they almost lost another Concorde shortly after it was restored to service when the FE mis-handled a fuel leak and the aeroplane narrowly avoided dead sticking into the North Atlantic when if landed on fumes at its nearest landfall, Halifax Nova Scotia.

No wonder they stopped operating it shortly afterwards, and shortly after that French politicking ended the BA operation as well. They were never going to allow the worlds only supersonic airliner, an Anglo-French aeroplane, to be operated by the British alone.

atakacs

5th Feb 2018, 18:28

According to the series of lectures given by the ex BA Concorde flight engineer, one of the best witnesses was the captain of Mitterrand's Airbus which was holding to cross the runway. Apparently he witnessed that there were signs of fire before the Concorde reached the metal strip. His testimony was not included.
Firstly it was president Chirac.
Secondly from their position they could obviously not see what caused the tire to shred. All there was too see was a dangerously off track burning Concorde passing uncomfortably close

Shaggy Sheep Driver

6th Feb 2018, 10:01

Firstly it was president Chirac.
Secondly from their position they could obviously not see what caused the tire to shred. All there was too see was a dangerously off track burning Concorde passing uncomfortably close

The name of the president is irrelevant. Pulse 1 did not say the 747 crew saw 'what caused the tyre to shred' he said they saw fire BEFORE the Concorde reached the metal strip.

hoss183

6th Feb 2018, 12:02

Fraser. Page 155 of the BEA Report states that (words to the effect) the analysis carried out shows that the absence of the Spacer had no affect on the aircraft crash.

Which should tell one something about how unbiased the report was to start with...

atakacs

6th Feb 2018, 13:01

The name of the president is irrelevant. Pulse 1 did not say the 747 crew saw 'what caused the tyre to shred' he said they saw fire BEFORE the Concorde reached the metal strip.
How could they conceivably affirm that ? Do you have any source ? And if so how credible is their assertion ? They were 1+ km where this happened !

Which should tell one something about how unbiased the report was to start with...
On this one I would agree - is there any rationale given for that conclusion ?

Buster15

6th Feb 2018, 15:13

The name of the president is irrelevant. Pulse 1 did not say the 747 crew saw 'what caused the tyre to shred' he said they saw fire BEFORE the Concorde reached the metal strip.

You have read the report I take it. Assuming that you have you will have noted that it was concluded that the tyre was CUT (not worn away) and that the cut matched the shape of the metal strip.
I prefer to rely on facts rather than conspiracy theories or maybe it was JFK ?

Shaggy Sheep Driver

6th Feb 2018, 15:47

You have read the report I take it. Assuming that you have you will have noted that it was concluded that the tyre was CUT (not worn away) and that the cut matched the shape of the metal strip.
I prefer to rely on facts rather than conspiracy theories or maybe it was JFK ?

You could try asking the guy that actually posted it. He's called Pulse 1.

I merely pointed out that atacacs had not read what Pulse 1 actually posted. Or what I posted either - see my post below.

Do keep up.

How could they conceivably affirm that ? Do you have any source ? And if so how credible is their assertion ? They were 1+ km where this happened !

Ask the guy who posted it, not me. You're as bad as Buster in not reading who posted what.