wikipediaAlternative theories
British investigators and former French Concorde pilots looked at several other possibilities that the report ignored, including an unbalanced weight distribution in the fuel tanks and loose landing gear. They came to the conclusion that the Concorde veered course on the runway, which reduced take-off speed below the crucial minimum. The aircraft had veered very close to a
Boeing 747 known to be carrying French President
Jacques Chirac.
[8]
They argued that the Concorde was in trouble
before takeoff, as it was overweight for the given conditions, with an excessively aft center of gravity and taking off downwind. When it stood at the end of the runway, ready to roll, it was more than six tonnes over its approved maximum takeoff weight for the given conditions.
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Moreover, it was missing the crucial spacer from the left main landing-gear beam that would have made for a snug-fitting pivot. This compromised the alignment of the landing gear and the wobbling beam and gears allowing three degrees of movement possible in any direction. The uneven load on the left leg’s three remaining tires skewed the landing gear disastrously, with the scuff marks of four tires on the runway showing that the plane was skidding out of control.
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Finally, Brian Trubshaw and John Cochrane, Concorde's two test pilots when the aircraft was being developed in the early 1970s, set the aft operating limit at 54 per cent - beyond that, they found, it risked becoming uncontrollable, likely to rear up backwards and crash, exactly as Flight 4590 did in its final moments over Gonesse. However, Flight 4590's centre of gravity went beyond 54 per cent, with the BEA stating a figure of 54.2 per cent, while a senior industry source said that the true figure may have been worse: with the extra fuel and bags, it may have been up to 54.6 per cent.
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These investigators were frustrated by the lack of cooperation from French authorities, including an unwillingness to share data and the immediate resurfacing of the Concorde's takeoff runway after the crash. They alleged that the BEA was determined to place the sole blame of the accident on the titanium strip to show that the Concorde itself was not at fault. The piece of metal from the DC-10 was found 7 meters forward, and 37 meters to the right of where the Concorde's tyre blew.
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The BEA's interim report maintained that the leftward yaw was caused not by incorrectly assembled landing gear but by loss of thrust from the number 1 and 2 engines. Data from the Flight Data Recorder
Black Box indicates that the aircraft was centred on the runway and accelerating normally up until the point where the tyre burst occurred. The instantaneous wind speed at the closest
anemometer to the take-off point was recorded as zero knots.
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