The BEA Interim Report (PDF) released Thursday covering the crash of Air France Flight 447 shows a span of more than nine hours between the last message received from the flight’s crew and the launch of a first rescue aircraft. Though communications on oversea flights can be sparse, the rescue launch order was still a full eight hours from the interval at which time the aircraft sent 24 messages showing onboard faults and system failures. When debris was found, it consisted mainly of light items from all areas of the plane. No evidence of fire or explosion has yet been discovered. Distortions in the metal vertical reinforcements of specific debris “showed evidence of great compressive forces” with crumpled walls and ceilings that were deformed downward while the floor “was curved under the effect of a strong upward pressure from below.” This suggests, and investigators have publicly stated, that the aircraft hit hard in a rather level attitude. The translated report summarizes it less obviously stating, “Visual examination showed that the airplane was not destroyed in flight; it appears to have struck the surface of the sea in a straight line with high vertical acceleration.” (There is some speculation as to the exact meaning of “in a straight line,” which may have translated directly to “in the line of flight,” but may have been intended to mean “in a level attitude,” or simply that the aircraft had negligible yaw at impact.)
Weather at the time of the accident as depicted by infrared images seven minutes before and after the last ACARS message show “the general conditions and the position of Inter-tropical Convergence Zone over the Atlantic were normal for the month of June.” However, investigators publicly announced that experienced teams working in simulators struggled to maintain control of the aircraft at cruise in turbulence with faulty air data. Messages sent automatically by the Airbus A330 accident aircraft show the aircraft was providing unreliable or conflicting air data to the pilots. The pilots were operating the aircraft at high altitude in turbulent conditions with forecast temperatures that were higher than normal (standard plus 13 degrees Celsius) making the thin air thinner and trimming controllability margins for the two co-pilots. Normal procedures suggest the captain may have been in the crew rest quarters at the onset of system failures. Without voice and data recorders, we may never know.
