Air France Flight 4590 - Event Summary

Event Summary

Post-accident investigation revealed that the aircraft was just at, if not exceeding, maximum takeoff weight for ambient temperature and other conditions, and up to one ton over maximum structural weight. As it left the gate, it was loaded such that the centre of gravity was excessively aft. Fuel transfer during taxi may have overfilled the number five wing tank. A twelve inch spacer that keeps the left main landing gear in alignment had not been replaced after recent maintenance, though the 2002 French Bureau Enquetes-Accidents investigation concluded that this did not contribute to the accident. The wind at the airport was light and variable that day, and was reported to the cockpit crew as an eight knot tailwind as they lined up on runway 26R. Over an hour delayed, the crew proceeded with take-off.

Five minutes before that decision, a Continental Airlines DC-10 departing for Newark, New Jersey, had lost a titanium alloy strip, 435 millimetres (17.1 in) long and about 29 millimetres (1.1 in) to 34 millimetres (1.3 in) wide, during takeoff from the same runway. French authorities have acknowledged that a required runway inspection was not completed after the Continental takeoff, as was protocol for Concorde takeoff preparation.

During the Concorde's subsequent take-off run, this piece of debris, still lying on the runway, cut a tyre, rupturing it. The sudden disruption of the centripetal force holding the tyre together sent debris flying about. A large chunk of this debris (4.5 kilograms or 9.9 pounds) struck the underside of the aircraft's wing structure at an estimated speed of 500 kilometres per hour (310 mph). Although it did not directly puncture any of the fuel tanks, it sent out a pressure shockwave that eventually ruptured the number five fuel tank at the weakest point, just above the undercarriage. Leaking fuel gushing out from the bottom of the wing was most likely to have been ignited by an electric arc in the landing gear bay or through contact with severed electrical cables. At the point of ignition, engines one and two both surged and lost all power, but engine one slowly recovered over the next few seconds. A large plume of flame developed; the Flight Engineer then shut down engine two, in response to a fire warning and the Captain's command.

Having passed V₁ speed, the crew continued the take-off but the plane did not gain enough airspeed with the three remaining engines, because the severed electrical cables prevented the retraction of the undercarriage. The aircraft was unable to climb or accelerate, and it maintained a speed of 200 knots (370 km/h; 230 mph) at an altitude of 60 metres (200 ft). The fire caused damage to the port wing, and it began to disintegrate – melted by the extremely high temperatures. Engine number one surged again, but this time failed to recover. Due to the asymmetric thrust, the starboard wing lifted, banking the aircraft to over 100 degrees. The crew reduced the power on engines three and four in an attempt to level the aircraft, but with falling airspeed they lost control and the jetliner stalled, crashing into the Hôtelissimo Les Relais Bleus Hotel near the airport.

The crew was trying to divert to nearby Le Bourget Airport, but accident investigators stated that a safe landing, given the aircraft's flight path, would have been highly unlikely.

As the cockpit voice recorder (CVR) transcript recorded it, the last intelligible words of the crew were (translated into English):

Co-pilot: "Le Bourget, Le Bourget, Le Bourget."

Pilot: "Too late (unclear)."

Control tower: "Fire service leader, correction, the Concorde is returning to runway zero nine in the opposite direction."

Pilot: "No time, no (unclear)."

Co-pilot: "Negative, we're trying Le Bourget" (four switching sounds).

Co-pilot: "No (unclear)."