On 3 March 2009, a DHC8-Q400 being operated by UK Regional airline Flybe on a scheduled passenger flight from Edinburgh to Southampton was making its approach at the planned destination in night Instrument Meteorological Conditions (IMC) and moderate turbulence when the aircraft was allowed to loose airspeed to below its minimum manoeuvring speed and a momentary stick shaker activation occurred. The associated automatic disconnection of the autopilot was followed by extreme pitch up and excessive roll left before the flight crew regained full control of the aircraft.
The event was not reported by the flight crew to anybody and only became known to the Operator three days later as a result of their Flight Data Monitoring Programme. Operator response was limited to a request to the aircraft commander to raise a Mandatory Occurrence Report (MOR), which was not received by the National Aviation Authority (NAA) until over three weeks after the event. The UK AAIB noted the MOR and determined that a Field Investigation by their organisation was required.
The investigation found that the stall warning had occurred whilst turning left in a slow descent just above 4000 ft QNH and under radar control with the Autopilot engaged in HDG and VS modes. With the trailing edge flaps still set to 0°, airspeed had fallen below the minimum for that condition. The response of the co pilot, who was PF, to the stick shaker activation and the abnormal aircraft attitudes which followed was found to have been slow and her recovery action not in accordance with Operator SOPs.
The underlying issue relating to the occurrence of the stall warning was the process for adjusting aircraft reference IAS on this aircraft type to account for icing conditions, the same issue that had been associated with the activation of stall protection during the fatal accident to an aircraft of the same type in the USA a few weeks earlier. See DH8D, vicinity Buffalo NY USA, 2009
The AAIB Investigation concluded that the flight crew "did not operate effectively, either individually or as a crew, in that they first allowed the aircraft to reach an undesirable situation and then did not deal with the situation in an entirely appropriate manner."
As a result of the Investigation, a comprehensive response was initiated by the Operator and deemed satisfactory by the NAA.
The Report of the Investigation was published on 10 June 2010 and may be seen at SKYbrary bookshelf: AAIB Bulletin: 6/2010 EW/C2009/03/03
No Safety Recommendations were made.