9

Following the initiation of the turn back to DXB, having been cleared to 27,000 ft, the crew requested an expedited, immediate descent to 10,000 feet (ft).

Following ATC clearance, the flight crew initiated a rapid descent to 10,000 ft. BAH-C advised the crew that the aircraft was on a direct heading to DXB and cleared for landing on DXB runway 12 left (RW12L) at their discretion.

The Fire Main Deck checklist was activated. According to the system logic, the cabin began to depressurise, PACKS 2 and 3 shut down automatically, and PACK 2 and 3 positions were then manually selected to OFF on the overhead panel in accordance with the checklist instructions. 6/7/8

Based on the DFDR data, at 15:15 UTC, PACK 1 shut down, with no corresponding discussion recorded on the CVR.

A short interval after the AP was disengaged, the CAPT informed the F/O that there was limited pitch control of the aircraft in the manual flying mode, the CAPT then requested the F/O to determine the cause of the pitch control anomaly.

The DFDR data indicates that there was a control column movement anomaly between the input by the crew on the control column forward and aft and the corresponding elevator movement: the elevator was not deflecting to the required range of travel relative to the control inputs.

During the turn back to DXB, the AP was re-engaged, and the aircraft descent was stabilised at 15:17 UTC.

At 15:17 UTC the CAPT told the F/O to pull the smoke evacuation handle 9 . This was not part of the Fire Main Deck Non-Normal checklist.

The CAPT informed BAH-C that the cockpit was ‘full of smoke' and commented to the F/O about the inability to see the instruments.

The CAPT instructed the F/O to input DXB into the Flight Management System (FMS). The F/O acknowledged the request and commented about the increasing flight deck temperature. It was not clear from the CVR if the FMS was programmed for DXB, although the DFDR indicated that the ILS/VOR frequency was changed to 110.1 MHz which was the frequency for DXB RW12L.

Based on the information available to date, it is likely that less than 5 minutes after the fire indication on the main deck, smoke had entered the flight deck and intermittently degraded the visibility to the extent that the flight instruments could not effectively be monitored by the crew.

At approximately 15:19 UTC, during the emergency descent, at approximately 20,000 ft cabin altitude, the CAPT, as PF, declared a lack of oxygen supply.

Following a brief exchange between the CAPT and F/O regarding the need for oxygen, the CAPT transferred control of the aircraft to the F/O as PF. Portable oxygen is located on the flight deck and in the supernumerary area, aft of the flight crew's positions when seated.

At this point the recorded CVR is consistent with the CAPT leaving his seat, after which there is no further CVR information that indicates any further interaction from the CAPT for the remainder of the flight.

TRANSIT FROM THE BAHRAIN TO EMIRATES FIR

The normal procedural requirement of transiting into the Emirates FIR, inbound for DXB was a radio frequency change from BAH-C to UAE-C.

At 15:20 UTC, BAH-C advised the crew to contact UAE-C with a frequency change to 132.15. At approximately the same time, the PF transmitted ‘mayday, mayday, mayday can you hear me?'.