Autopilot would have stabilised zoom-climb A340: inquiry

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Investigators have determined that the autopilot of the Air France A340 involved in a zoom-climb incident over the Atlantic last year would have stabilised the aircraft if it had not been disconnected.

During the 22 July 2011 event near Guadeloupe the aircraft climbed rapidly from 35,000ft to 38,000ft shortly after an overspeed warning, after one of the pilots disengaged the autopilot and made nose-up pitch inputs.

Analysis of the flight data by French investigation agency BEA found the increase in the aircraft's altitude would have been limited to only 200ft (60m) if the autopilot had been left active.

Examination of several severe turbulence events, says the BEA, indicates that adverse consequences "can be minimised" if pilots keep the automated systems, such as the autopilot, engaged and "avoid an instinctive reaction" to recover the aircraft manually.

Circumstances of the A340 event share similarities with the moments preceding the loss of Air France flight AF447 two years earlier, when an encounter with convective weather, the disengagement of the autopilot, and nose-up pitch inputs resulted in the Airbus A330 climbing from 35,000ft to 38,000ft and stalling.

The inquiry believes the A340's overspeed in the Guadeloupe incident was the result of a convective weather encounter.

In the wake of the incident, the BEA has recommended that pilots be better trained in the understanding and use of weather radar, to ensure that they can assess cumulonimbus cloud development. The A340 crew had mostly kept the radar range setting at 320nm (590km), while Air France required 160nm or 80nm.