Concorde 4590
 

What specifically caused the Concorde to go out of control when it did?

I've heard 3 versions. That it was barely at flying speed when it took off and there was a further loss of engine power. That the fire from the front fuel tank move the C of G (already a bit too far back) to move even further. Or that the fire burned through the hydraulics.

The third one sounds most plausible to me but opinions vary.

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

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

I think that's a fair summary.

To be honest once that fire started they were all pretty much doomed.

I appreciate that, but I was curious as to what exactly caused the loss of control. The report (thanks Buster15) suggests it was the control surfaces being burned away. There was a suggestion in some quarters that the airspeed being low and/or the C of G issues meant it would not have made Le Bourget even without the fire.

I don't think you will ever get a definitive answer to that.
They were flying too slow a burning aircraft with insufficient thrust, degrading aerodynamics, failing hydraulics and deforming control surfaces with uncontrolable CoG. Take your pick....

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.

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.

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.

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

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

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.

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.

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.

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.

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.

The video tells you the course of action to take.