To assist those who are still asking about fuel in the centre tank and how/when the autopilot disconnected ... I quote from the:
AAIB Bulletin S1/2008 SPECIAL
Published February 2008
I know that everyone participating in this thread has already read it but here are two items.
At 1,000 ft the aircraft was fully configured for the landing, with the landing gear down and flap 30 selected. The total fuel on board was indicating 10,500 kg, which was distributed almost equally between the left and right main fuel tanks, with a minor imbalance of about 300 kg. The fuel crossfeed valves indicated that they were closed and they had not been operated during the flight.
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The airspeed reduced as the autopilot attempted to maintain the ILS glide slope and by 200 ft the airspeed had reduced to about 108 kt. The autopilot disconnected at approximately 175 ft ...
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The recorded data indicates that there were no anomalies in the major aircraft systems. The autopilot and the autothrottle systems behaved correctly and the engine control systems were providing the correct commands prior to, during, and after, the reduction in thrust.