On 9 February 2014, a RAF Voyager ZZ333 (Voyager being the UK military designation of the Airbus A330 MRTT (Multi Role Tanker Transport), a derivative of the Airbus A330-200) on a passenger flight from RAF Brize Norton to the airfield at Camp Bastion, Afghanistan and in the cruise in day VMC at FL 330 over Turkey suddenly and very rapidly lost over 4000 feet of altitude. Almost all those of the 198 occupants who were unrestrained at the time were “thrown towards the ceiling” with “a number of minor injuries resulting”. After recovery to controlled flight, a diversion was made to the Turkish airbase at Incirlik.
The Inquiry found that there was no evidence of system failure causation. FDR data showed that “the Captain’s side-stick moved at one minute and 44 seconds prior to the event” and introduced a “sustained, small pitch-down command of 0.8 degrees” and then moved again at the onset of the event when it introduced “a sustained, fully-forward pitch-down command”. It was also found from the recorded data that the Captain’s seat had moved at exactly the same time as both these side stick movements. Evidence linking the concurrent seat and side stick movements was found “in the form of a Digital SLR camera obstruction which was in-front of the Captain’s left arm rest and behind the base of the Captain’s side-stick at the time of the event”.
It has been established that at the time of the incident, the aircraft commander was acting as PF with AP1 engaged and was alone in the flight deck because the Co-pilot had left his seat and was in the forward galley near the forward left hand passenger door. Upon a sudden and rapid pitch down of the aircraft, the PF reported having “attempted to take control by pulling back on his side-stick controller and pressing the auto-pilot disconnect button” but had found that these actions were ineffective. The First Officer reported having been propelled upwards by the sudden onset of negative G and striking the cabin roof. However, he had been able to re-enter the flight deck through the open door where he described finding “a disorderly scene with audio alarms sounding and a violent shaking of the aircraft” and had “reached down to pull back on the side-stick control” which was followed by an audio alert of dual input. The First Officer reported that as the aircraft began to recover from the dive, he had become aware of a rapid increase in speed and had “called for the thrust levers to idle” which had had the desired effect. The Commander then regained control, set TOGA thrust and eventually re-established “a power attitude combination for straight and level flight at FL310”.
It was found that during the excursion, the aircraft had lost 4400 feet of altitude in a period of 27 seconds, at one point reaching a rate of descent of approximately 15000 fpm. Recovery back towards controlled flight was found to have been “initiated by the self protection system”.
Analysis of the camera involved confirmed that it was being used in the three minutes prior to the event and forensic analysis of damage to the camera body indicated that it had experienced “significant compression against the base of the side-stick, consistent with having been jammed between the arm rest and the side-stick unit”. Given corroboration of this scenario through crew interviews, the Inquiry “has confidence that the pitch-down command was the result of an inadvertent physical input to the Captain’s side-stick by means of a physical obstruction (the camera) between the arm-rest and the side-stick unit”.
The formally stated conclusion based on investigation so far was that “given the weight of evidence, the Service Inquiry is confident that the cause of the event was Human Factors”.
Since it has been demonstrated by recreating the incident scenario that an object inadvertently lodged in the space between the arm rest and the side-stick can generate an identical pitch-down command to that seen, “safety advice has been issued to the RAF and to Airbus to highlight this possibility”.
An Interim Report of progress made by the Inquiry was completed on 17 March 2014 and published on 19 March 2014. This notes that “the inquiry continues to pursue a standard of evidence that will allow other lines of inquiry to be closed across a range of possible causes” and will be examining “other factors, such as the post-occurrence management of the event, in order to identify any relevant lessons that may enhance Air Safety”.
- Loss of Control
- Recovery from Unusual Aircraft Attitudes
- Aerodynamic Stall Awareness and Avoidance
- Human Error Types
- Error Management (OGHFA BN)
- Using “Positive” Human Factors Data (OGHFA BN)