Air France Flight 4590

Event summary

Post-accident investigation revealed that the aircraft was at or over the maximum takeoff weight for ambient temperature and other conditions, and 810 kilograms (1,790 lb) over the maximum structural weight. As it left the gate, it was loaded such that the centre of gravity was aft of the take-off limit. Fuel transfer during taxiing left the number five wing tank 94% full. A twelve-inch spacer that normally keeps the left main landing gear in alignment had not been replaced after recent maintenance; however, the French Bureau for Accident 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.

Five minutes before the Concorde, a Continental Airlines DC-10 departing for Newark, New Jersey, had lost a titanium alloy strip (part of the engine cowl, identified as a wear strip), 435 millimetres (17.1 in) long, 29 to 34 millimetres (1.1 to 1.3 in) wide and about 1.4 millimetres (0.055 in) thick, during takeoff from the same runway. A runway inspection, scheduled for 15h, had not been carried out.

During the Concorde's takeoff run, this piece of debris still lying on the runway, was run over, cutting a tyre and rupturing it. A large chunk of tyre debris (4.5 kilograms or 9.9 pounds) struck the underside of the aircraft's wing at an estimated speed of 140 metres per second (310 mph). Although it did not directly puncture any of the fuel tanks, it sent out a pressure shockwave that 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 ignited by an electric arc in the landing gear bay or through contact with hot parts of the engine. 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. Air traffic controller Gilles Logelin noticed the flames before the Concorde was airborne, however with only 2 km (1.2 mi) of runway remaining and travelling at a speed of 328 km/h (204 mph), its only option was to take off. The Concorde would have needed at least 3 km (1.9 mi) of runway to abort safely.

Having passed V1 speed, the crew continued the takeoff, but the plane did not gain enough airspeed with the three remaining engines, because damage to the landing gear bay door prevented the retraction of the undercarriage. The aircraft was unable to climb or accelerate, maintaining 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, which 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 aircraft 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 in the cockpit (translated into English) were:

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)."

Concorde grounded

Up until the crash of Air France Flight 4590 in 2000, the Concorde SST had been considered among the world's safest planes. The crash of a Concorde contributed to the end of the aircraft's career.

A few days after the crash, all Concordes were grounded, pending an investigation into the cause of the crash and possible remedies.

Air France's Concorde operation had been a money-losing venture, but it is claimed that the airplane had been kept in service as a matter of national pride; British Airways, however, claimed to make a profit on its Concorde operations. According to Jack Lowe, a Concorde pilot, up until the crash of Air France Flight 4590 at Paris, the British Airways Concorde operation made a net average profit of about £30m a year. Revenue service was resumed in 2001, until the remaining aircraft were retired in 2003.

Accident investigation

The official investigation was conducted by France's accident investigation bureau, the BEA, and it was published on 16 January 2002.

Conclusions

The investigators concluded that:

• The aircraft was overloaded by 810 kilograms (1,790 lb) above the maximum safe takeoff weight. Any effect on takeoff performance from this excess weight was negligible.
• After reaching takeoff speed, the tyre of the number 2 wheel was cut by a metal strip (a wear strip) lying on the runway, which had fallen from the thrust reverser cowl door of the number 3 engine of a Continental Airlines DC-10 which had taken off from the same runway five minutes previously. This wear strip had been replaced at Tel Aviv, Israel, during a C check on 11 June 2000. Further maintenance work had been performed at Houston, Texas, but the strip had been neither manufactured nor installed in accordance with the procedures as defined by the manufacturer.
• The aircraft was airworthy and the crew were qualified. The landing gear that later failed to retract had not shown serious problems in the past. Despite the crew being trained and certified, no plan existed for the simultaneous failure of two engines on the runway, as it was considered highly unlikely.
• Aborting the takeoff would have led to a high-speed runway excursion and collapse of the landing gear, which also would have caused the aircraft to crash.
• While two of the engines had problems and one of them was shut down, the damage to the plane's structure was so severe that the crash would have been inevitable, even with the engines operating normally.