af4590

On 25 July 2000, Air France Flight 4590, a Concorde passenger jet on an Air France international charter flight from Paris to New York, crashed shortly after takeoff, killing all 109 people on board and 4 on the ground. It was the only fatal Concorde accident during its 27-year operational history.

Whilst taking off from Charles de Gaulle Airport, Air France Flight 4590 ran over debris on the runway dropped by an aircraft during the preceding departure, causing a tyre to explode and disintegrate. Tyre fragments, launched upwards at great speed by the rapidly spinning wheel, violently struck the underside of the wing, damaging parts of the landing gear – thus preventing its retraction – and causing the integral fuel tank to rupture. Large amounts of fuel leaking from the rupture ignited, causing a loss of thrust in the left side engines 1 and 2. The aircraft lifted off, but the loss of thrust, high drag from the extended landing gear, and fire damage to the flight controls made it impossible to maintain control. The jet crashed into a hotel in nearby Gonesse two minutes after takeoff. All nine crew and one hundred passengers on board were killed, as well as four people in the hotel. Four other people sustained slight injuries.

In the wake of the disaster, the entire Concorde fleet was grounded. Following the implementation of various modifications to the airframe, it returned to service on 7 November 2001. However, due to limited commercial success, especially in the wake of the September 11 attacks, Concorde aircraft were retired by Air France in May 2003 and by British Airways that November.

INVESTIGATION

Conclusions

The BEA 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 that 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, and then again at Houston, Texas, on 9 July 2000. The strip installed in Houston 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.

Additional factors and alternative theories

Former British Airways Concorde captain John Hutchinson said the fire on its own should have been 'eminently survivable; the pilot should have been able to fly his way out of trouble'. Hutchinson believed this did not happen due to a series of operational errors and 'negligence' by the maintenance department. According to a report in a British newspaper, by journalist David Rose, the crash had "more than one contributing factor, most of which were avoidable."

While examining the wreckage in a warehouse, investigators noticed that a spacer was missing from the bogie beam on the left-hand main landing gear. (It was later found in an Air France maintenance workshop.)This skewed the alignment of the landing gear because a strut was able to wobble in any direction with 3° of movement. The problem was exacerbated on the left gear's three remaining tyres by the uneven fuel load. Drag marks left on the runway by the left rear landing wheels show the Concorde was veering to the left as it accelerated toward takeoff. Photographs in the BEA report showed a smashed steel landing light, clipped by the aircraft, parts of which were probably ingested by engine number 1.

According to Rose, former French Concorde pilot Jean-Marie Chauve and former Concorde flight engineer Michel Suaud spent six months preparing a 60-page report which was submitted to the investigating judge. They re-evaluated two factors that the BEA had found to be of negligible consequence to the crash, the unbalanced weight distribution in the fuel tanks and the loose landing gear. Chauve and Suaud gave detailed calculations, stating that without the retardation caused by the missing undercarriage spacer, the aircraft would have taken off 1,684 metres (5,525 ft) from the start of the runway, before the point where the metal strip was located, although the BEA disputed this, saying the acceleration was normal.

At the start of the takeoff, the aircraft had 1.2 tonnes of extra fuel which should have been burnt during the aircraft's taxi. Nineteen items of luggage, weighing some 500 kg (0.5 tonnes) were loaded onto the aircraft at the last minute without being included in the aircraft's manifest, giving the aircraft a weight of 186 tonnes, which exceeded the aircraft's certified maximum structural weight by 1 tonne. A change in wind conditions created an 8-knot tailwind, which would have reduced the regulated takeoff weight to 180 tonnes, 6 tonnes below the actual aircraft weight. Rather than taking off from the other end of the runway, in order to take off into the wind, no change in takeoff direction occurred. The additional weight of the extra fuel in tank 11, the rearmost tank, plus the additional luggage shifted the aircraft's centre of gravity rearwards, to beyond the safe operating limit of 54 percent, set by the Concorde test pilots. Once the damaged forward tank 5 began to lose fuel, the centre of gravity moved even further rearward. At one point, it drifted toward a just-landed Air France Boeing 747 that was carrying then-French President Jacques Chirac (who was returning from the 26th G8 summit meeting in Okinawa, Japan). As the plane was about to leave the runway, with the aircraft rotated for takeoff, its speed was only 188 knots, 11 knots under the minimum recommended velocity. The flight engineer shut down engine number two at only 25 feet altitude. The procedure for shutting down an engine is to wait until