A Royal Air Force (RAF) Airbus KC2 Voyager lost 4400 feet when a digital camera became wedged near the captain’s sidestick, a preliminary report into the incident revealed.
On February 9, 2014 an RAF Airbus A330, modified as a Multi Role Tanker Transport (MRTT), departed RAF Brize Norton on a transport flight to Camp Bastion Air Base in Afghanistan. On board were 189 passengers and nine crew members.
With the aircraft in the cruise at FL330 over Turkey and auto-pilot 1 engaged, the co-pilot had left his seat and was in the forward galley in the vicinity of the forward left passenger door. The captain reported that he suddenly felt a sensation of weightlessness and being restrained by his harness, accompanied by a rapid pitching down of the aircraft. He attempted to take control by pulling back on his side-stick controller and pressing the auto-pilot disconnect button but these actions were ineffective.
Immediately prior to the pitch-down, the co-pilot reported feeling a sensation similar to turbulence. The co-pilot then experienced weightlessness and struck the cabin roof but was able to re-enter the flight deck through the open door. He reported a disorderly scene with audio alarms sounding and a violent shaking of the aircraft. He reached down to pull back on the side-stick control. Both pilots report hearing a dual input audio warning, indicating simultaneous inputs by both pilots on their respective side-sticks. As the aircraft began to recover from the dive, the co-pilot was aware of excessive speed building and called for the thrust levers to idle which decreased the speed rapidly.
The captain took control, setting Take-off and Go-around power and subsequently re-establishing a power attitude combination for straight and level flight at FL310. The aircraft had lost 4,400 feet in 27 seconds, registering a maximum rate-of-descent of approximately 15,000 feet per minute.
The aircraft was diverted to Incirlik Air Base in southern Turkey without further incident.
The Flight Data Recorder and Cockpit Voice Recorder information showed that the captain’s side-stick moved at one minute and 44 seconds prior to the event (introducing a sustained, small pitch-down command of 0.8 degrees) 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 at those times.
The movement of the seat was linked 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 arm rest and behind the base of the Captain’s side-stick at the time of the event. Analysis of the camera has confirmed that it was being used in the three minutes 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 arm rest and the side-stick unit. Crew interviews have corroborated this evidence.
As such, the U.K. Military Aviation Authority’s investigators have 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. 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 arm rest and the side-stick, generating an identical pitch-down command to that seen during the incident. Safety advice has been issued to the RAF and to Airbus to highlight this possibility.
- MAA interim report (PDF)