Three years after France's worst air crash, government investigators on Thursday released a final report on the accident that paints a vivid picture of pilots who, confused by faulty air-speed data during a thunderstorm, struggled to save the jet but wound up causing it to stall and plunge into the Atlantic Ocean. All 228 people aboard were killed.
Key moments of the flight as outlined in the final report by the French air accident investigation agency:
May 31, 2009
10 p.m. GMT— 216 passengers and 12 crew members — including three pilots — have boarded the Air France flight 447 in Rio de Janeiro. The computers of the Airbus A330 have been programmed for the flight to Paris.
10:29 p.m.— Flight 447 takes off. A co-pilot, rather than the captain, is flying.
June 1, 2009
Midnight— The plane is cruising at 35,000 feet. The autopilot and autothrust are on.
1:35 a.m.— The plane makes its last radio contact with Brazilian air traffic control. Attempts to make contact with air traffic control in Dakar, Senegal, fail.
1:45 a.m. — The plane enters a slightly turbulent zone. A co-pilot notes that they are "entering the cloud layer" and that it would have been better if they had been able to climb higher.
2 a.m. — The captain attends a briefing between the two co-pilots. The turbulence has stopped, but the pilots anticipate more ahead. The captain then leaves the cockpit.
2:10 a.m. and 5 seconds — The autopilot and then the autothrust suddenly disconnect. The co-pilot flying the plane says, "I have the controls." As the plane begins to roll right, he points the noise up while trying at the same time to counter the roll. A stall warning is triggered briefly twice. Data retrieved by crash investigators indicates that speed information visible to pilots on the left cockpit display erroneously shows the speed has dropped sharply from 275 knots to 60 knots — too slow a speed to fly. That's also what's displayed on a standby instrument system. The information on the right cockpit display is unknown.
The crew doesn't disconnect the flight director — the computer system that manages flight information — in order to fly manually. Flying manually and continuing to fly levelly in the same direction at the same speed would have been the correct response, safety experts would say later.
2:10 a.m. and 16 seconds — The co-pilot not flying says, "We've lost the speeds." The pilot flying struggles to keep the plane from rolling while sharply increasing its pitch upwards. The plane's computers spit out warning messages, which the pilot not flying reads out in a disorganized manner. He says the plane is climbing and several times asks the pilot flying to descend. If a plane is about to stall, pilots are supposed to point the aircraft downward to pick up speed in order to regain control. The pilot flying makes several nose-down inputs that decrease the up angle of the plane and its climbing speed, but the plane — then at about 37,000 feet — continues to climb.
2:10 a.m. and 36 second — The speed information on the left cockpit flight display becomes valid again, showing a speed of 223 knots, although the speed on the standby system is still erroneous. The plane has lost about 50 knots since the autopilot disconnected and the plane began to climb. The speed on the left side was incorrect for 29 seconds. The plane appears to briefly level off and stop rolling, but then begins to climb again.
2:10 a.m. and 50 seconds — The pilot not flying calls the captain several times. As he calls, the stall warning is triggered again and continues to sound. The pilot flying makes more nose-up inputs. Airspeed drops to 185 knots and is displayed correctly on both the left, right and standby cockpit displays.
2:11 a.m. and 37 seconds — The pilot who had not been flying the plane takes the controls with little warning, but the pilot who had been flying almost immediately takes back control. A few seconds later the captain re-enters the cockpit. All recorded speeds become invalid and the stall warning stops after having sounded continuously for 54 seconds. The pilot flying makes another nose-up input, which lasts about 30 seconds.
2:12 a.m. and 2 seconds — The pilot flying says, "I have no more displays," while the pilot not flying says, "We have no valid indications." About 15 seconds later, the pilot flying then tries to point the nose down. The angle at which the plane is pointed begins to lower, the speed information becomes valid on the displays again and the stall warnings begin to sound again.
2:13 a.m. and 32 seconds — The pilot flying notes that the plane is losing altitude. Fifteen seconds later, both he and the other co-pilot simultaneously try to send flight instructions to the plane's computers. The pilot flying then tells the other co-pilot, "Go ahead, you have the controls."
2:14 a.m. and 17 seconds — A crash warning system begins to continuously sound, first alerting "sink rate, sink rate" and then "pull up, pull up."
2:14 a.m. and 28 seconds — The crash warnings stop. The plane slams into the ocean belly first.