Operational procedures and take-off calculations remain in the frame as accident investigators continue probe
Centre-of-gravity problems and aircraft technical faults have been ruled out as causes of last month's Emirates Airbus A340-300 take-off incident at Johannesburg airport, South Africa, according to sources close to the investigation (Flight International, 20-26 April).
However, South African Civil Aviation Authority chief accident investigator, Dr Andre de Kock, declines to comment, and the aircraft manufacturer will say only that it has not been instructed - nor had cause - to issue any technical or operational advice to A340 operators as a result of the event.
The aircraft, bound for Dubai with 216 passengers and 14 crew on 9 April, began its take-off roll on Johannesburg's 4,420m (14,490ft) long runway 21R, but did not get airborne until it had passed beyond the end of the runway, blowing three main gear tyres and damaging the flaps, which subsequently locked in a partly deployed position. It then returned to land having dumped fuel.
Flight International has obtained details of the take-off run from sources close to the investigation: the aircraft rotated to 6º nose up at a calculated rotate speed (VR) of 150kt (278km/h); the pitch was then reduced to 3.5º before increasing again as the crew selected take-off/go-around (TOGA) thrust; Unstick occurred at 175kt, 17s after initial rotation with 9º nose up. When the aircraft returned for landing four more of its tyres burst on touchdown, but the landing roll was completed safely.
The A340-300 flightcrew operating manual (FCOM) advice for take-off is, at VR, to begin rotation at a steady rate of 2.5-3º/s toward 12.5º nose-up attitude. Providing VR is correct, according to the FCOM, the aircraft will have left the ground by the time a 12.5º pitch angle has been attained. Tailscrape angle for the A340-300 with oleos not compressed is given as 14º in the manual.
Although 150kt was the VR the crew used, sources close to the investigation cannot say whether or not this was the correct VR for the prevailing weight, altitude and temperature. The sources add that they are not aware of the crew having attempted to use anything less than the whole runway length for the take-off.
Emirates declines to comment on the information.
DAVID LEARMOUNT / LONDON