DAVID LEARMOUNT / LONDON
AAIB disputes procedures in French crash investigation
French and British authorities are in disagreement over the handling of the investigation into the 25 July 2000 Aerospatiale/British Aerospace Concorde crash. But both parties agree on the fundamental causes laid out in the Bureau d'Enquetes Accidents (BEA) final report published on 16 January.
Dissent by the UK Air Accident Investigation Branch (AAIB) is appended to the BEA report. The main complaint is that the involvement of the judiciary from the beginning of any French accident inquiry slows the technical investigation, and that Concorde crash evidence the AAIB wished to examine was either actively withheld, or the AAIB was only allowed to examine it briefly.
The Concorde crashed soon after take-off from runway 26R at Paris Charles de Gaulle airport, France, when the aircraft's No 2 port main- gear tyre exploded after it was cut by a strip of metal from another aircraft. The BEA says tyre debris pierced the No 5 fuel-tank within the left wing, and the resulting fuel stream caught fire. Hot air, debris and some unburned fuel entered the engine intakes, reducing available engine power.
But the AAIB says it believes it has not been proven that wing-piercing was the result of hydraulic shock. The report says, following the tyre-burst just after take-off-decision speed, the aircraft veered left, with the port gear entering soft ground. The aircraft had caught fire on the ground and air traffic control warned the crew of this.
According to the report, the crew rotated the aircraft for take-off 15kt (30km/h) before reaching the planned 183kt. This put the aircraft in a position from which it was almost impossible to accelerate after the two left engines began to lose power. The gear also would not retract, increasing drag.
Following a fire warning on No 2 engine, the flight-engineer began to shut it down, and the captain told him to carry out the fire drill, which he did.
The aircraft was left with three operating engines, the gear stuck down and the No 1 engine losing power. According to the report, the minimum speed (Vzrc) to maintain a zero climb rate in Concorde with power on three engines and the gear down is 205kt, and with two engines inoperative more than 300kt.
The highest speed achieved by the aircraft was less than 211kt before the power on No 1 engine began to run right down, and the speed began dropping until the aircraft became unflyable.