http://www.bbc.co.uk/news/uk-england-bristol-33615527
https://www.youtube.com/watch?v=F-1zD6_Yjig (5:08 minutes)

25 years ago 113 lives came to an abrupt, horrifying end, and the British nation's love affair with a noisy, expensive, beautiful aeroplane died with them.

25 July 2000: Air France Flight 4590 was a Concorde flight operated by Air France which was scheduled to run from Charles de Gaulle International Airport near Paris, to John F. Kennedy International Airport in New York City. It crashed in Gonesse, France just 2 minutes after take-off & 6.4km (4 miles) from the airport. All one hundred passengers and nine crew members on board the flight died. On the ground, four people were killed with one left injured.

Until that day Concorde had a perfect safety record,  plus a terrifying vulnerability that each manufacturer kept secret.

Concorde was a joint project between the British Aircraft Corporation (BAC) & Aérospatiale (the French insisted on the 'E' at the end of the name). The first flight was on 2 March 1969 & it entered into service for both nations on 21 January 1976.

It was fantastically noisy and, because it flew faster than sound (Mach 2.04) (~2,179 km/h (1,354 mph) cruising speed), had a habit of breaking windows on the ground. I visited G-AXDN Concorde at the Imperial War Museum, Duxford; I recall the cabin as being incredibly narrow. It drank aviation fuel like there was no tomorrow (4,800 gallons per hour (22,000 L/h) at 60,000 feet (18,000 m) cruising). It cost a small fortune to fly within. Every other developed nation in the world tried to kill it, and the Brits absolutely loved it. It may have been a noisy, dirty, expensive beast but it was their noisy, dirty expensive beast and beautiful as well. Plus--apart from the Russians (the Tupolev Tu-144, rapidly withdrawn from service)--no-one else had one.

The design inspiration for Concorde began in the mid-1950s. Preparation continued throughout the period & finally a draft treaty was signed on 29 November 1962 between the UK & French governments. A promotional advertisement in the 29 May 1967 issue of Aviation Week & Space Technology suggested a market of 350 aircraft by 1980. The consortium actually got non-binding orders for 100 aircraft, and most of those were doomed to be cancelled (a Tu-144 crashing at the Paris Air Show did not help, and neither did the spiralling cost of fuel).

The Boeing 747 Jumbo Jet entered service in 1970 and, from that moment, America did everything it could to kill Concorde dead. They almost completely succeeded. In the end just 20 Concorde were built; 7 were delivered to France, 7 to the UK & 6 were kept as "prototype and development aircraft". Although that meant that it never made back it's development costs, the aircraft were financially successful throughout their time until the crash, making a net average profit of about £30m a year (£500m net across the lifetime). It took less than half the time of any other aircraft to get from Europe/UK to the USA (3.5 hours cf 8 hours), and there were plenty of high net-worth individuals and/or companies willing to pay to do that.

The aircraft was a development & construction marvel:

• the first aircraft to have computer-controlled engine air intakes
  (imagine what air entering at mach2 would do to the engines) ("blow them to pieces" is the answer - they had to slow it down, quickly)
  (each Concord had 4 x Rolls-Royce/Snecma Olympus 593 TurboJet engines)
• carbon-fibre brakes (1960, remember)
• fly-by-wire (analogue, not electronic)
• a droop-nose
  (the long, long nose angled down during take-off/landing to improve visibility)
• the cruising height was about the same as the SR71 Blackbird
• supersonic flight caused such extraordinary heating that the fuselage would expand by as much as 300 mm (almost 1 ft).
  (it was this that limited the max speed to mach2)
• Concorde burned two tonnes of fuel (almost 2% of the maximum fuel load) just taxiing to the runway.
  (the tubojet engines are very efficient at supersonic flight, but exceptionally inefficient at low speed)

There was one, small feature that was spotted but never fixed: the fuel tanks were vulnerable from below, and armouring was considered but never added. For 24 years this vulnerability made no difference but then, on that fateful day in 2000, a series of unfortunate events culminated together:-

1. The plane had an additional 1000 pounds of luggage which never made it to the pilots manifest.
   (the plane's trim is auto-maintained by pumping fuel between 13 fuel tanks; that relies on knowing the plane's weight exactly)
2. A maintenance worker neglected to reinstall a spacer in the left wheels to keep them straight, causing the plane to screw left.
3. An earlier plane dropped a strip of metal onto the runway.
4. That strip was not spotted and/or not cleared.
5. Flight 4590 hit the metal shortly before rotation ('rotation' is when the aircraft lifts itself up, so that only the rear wheels are on the tarmac; the wings on Concorde have zero lift until that moment)
6. The metal burst the front right tyre on the left landing gear bogie.
7. That tyre threw debris up  against the underside of the wing, causing the Number 5 fuel tank to rupture (take-off speed was very high at 250 miles per hour (400 km/h), and thus tyre pressures were also high)
8. Debris also entered the 2 left-side engines
   (Number 2 engine indicated a fire alarm, and was then shut down by the crew as it was only producing near-idle power)
9. Number 5 fuel tank had been auto-filled to capacity by the system; the leaking fuel burst into flame; the crew did not notice this.
10. We are now at the situation shown in the photograph at top (taken by a video camera operated by a passenger in a car passing the airfield) (the crew & passengers have less than 90 seconds to live)
11. The crew try to retract the undercarriage (vital to reduce drag at such low speeds) (it is damaged & fails to retract)
12. Air Traffic Control inform the crew that fire is coming from below the port wing.
13. The crew inform air traffic control that they will head for the nearest airport at Le Bourget.
14. The Number 1 engine now loses thrust. It is impossible.
15. At 200 feet altitude and with an airspeed of around 200 knots she pitches up in the air, increases her angle of bank rapidly, then crashes back down on to a hotel at Gonesse. 100 passengers. 9 crew members. 4 people at the hotel. Gone in moments.

Air France grounded it's entire Concorde fleet immediately. British Airways cancelled the afternoon flights, but then resumed normal service. They kept going until the writing was on the wall. They stopped on 15th August 2000 & the next day the Concorde certificate of airworthiness was withdrawn, effectively grounding all of the remaining fleet.

All it needed was a few layers of kevlar, but they didn't do it. And 113 people died.

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Alex Kemp