A digital single-lens reflex (SLR) camera becoming wedged between the pilot's armrest and side-stick control column caused a UK Royal Air Force Airbus A330-200 Voyager tanker-transport aircraft, en route to Afghanistan, to plummet several thousand feet before making an emergency landing in Turkey, a preliminary investigation has found.
The interim report, which was released by the Military Aviation Authority (MAA) on 17 March, concluded that the 9 February incident involving Voyager ZZ333 occurred when a movement of the captain's left-hand seat moved the armrest forward, which in turn forced the camera into the side-stick control column.
"The flight data recorder and cockpit voice recorder have shown that the captain's side-stick moved ... prior to the event (introducing a sustained, small pitch-down command ...) and again at the onset of the event (introducing a sustained, fully forward pitch-down command). The recorders have also shown that the captain's seat moved ... prior to the event, and at the onset of the event," the report noted.
"The [investigating] panel has found evidence to link the movement of the seat to the movement of the side-stick, in the form of a digital SLR camera obstruction, which was in front of the captain's left armrest and behind the base of the captain's side-stick. Analysis of the camera has confirmed that it was being used ... leading up to the event. Furthermore, forensic analysis of damage to the body of the camera indicates that it experienced a significant compression against the base of the side-stick, consistent with having been jammed between the armrest and the side-stick unit. Crew interviews have corroborated this evidence.
"Simulations have been carried out which have re-created the scenario, which has shown that it is possible for objects to become inadvertently lodged in the space between the armrest and the side-stick, generating an identical pitch-down command to that seen during the incident."
According to the report, this unintended input resulted in the aircraft losing 4,400 feet in 27 seconds, registering a maximum rate-of-descent of approximately 15,000 feet per minute, before the self-protection system initiated a recovery back towards controlled flight. There were nine crew and 189 passengers on board, many of whom suffered minor injuries. The aircraft diverted to Incirlik Airbase in Turkey, with the rest of the fleet of six aircraft being temporarily grounded until the cause was found.
"Given the weight of evidence, the Service Inquiry is confident that the cause of the event was [a result of] human factors. Nevertheless, 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. In accordance with its terms of reference, the Service Inquiry continues to examine other factors, such as the post-occurrence management of the event, in order to identify any relevant lessons that may enhance air safety," the MAA report concluded.
All UK Voyagers were cleared to resume flight operations on 21 February.