At 02:10:05 UTC the autopilot disengaged and the airplane transitioned from normal law to alternate law.[21][Note 1] The engines' auto-thrust systems disengaged three seconds later. Without the auto-pilot, the aircraft started to roll to the right due to turbulence, and the pilot reacted by deflecting his side-stick to the left. One consequence of the change to alternate law was an increase in the aircraft's sensitivity to roll, and the pilot's input over-corrected for the initial upset. During the next thirty seconds, the aircraft rolled alternately left and right as the pilot adjusted to the altered handling characteristics of his aircraft.[22] At the same time he made an abrupt nose-up input on the side-stick, an action that was unnecessary and excessive under the circumstances.[23] The aircraft's stall warning sounded briefly twice due to the angle of attack tolerance being exceeded, and the aircraft's recorded airspeed dropped sharply from 274 knots to 52 knots. The aircraft's angle of attack increased, and the aircraft started to climb. By the time the pilot had control of the aircraft's roll, it was climbing at nearly 7,000 ft/min.[22]
At 02:10:34, after displaying incorrectly for half a minute, the left-side instruments recorded a sharp rise in airspeed to 215 knots, as did the Integrated Standby Instrument System (ISIS) another half a minute later [24] (the right-side instruments are not recorded by the recorder). The icing event had lasted for just over a minute.[25][26][27] The pilot continued making nose-up inputs. The trimmable horizontal stabilizer (THS) moved from three to thirteen degrees nose-up in about one minute, and remained in that latter position until the end of the flight.
At 02:11:10 UTC, the aircraft had climbed to its maximum altitude of around 38,000 feet. There, its angle of attack was 16 degrees, and the thrust levers were in the Takeoff/Go-around detent (fully forward), and at 02:11:15 UTC the pitch attitude was slightly over 16 degrees and falling, but the angle of attack rapidly increased towards 30 degrees. A second consequence of the reconfiguration into alternate law was that "stall protection" no longer operated. Whereas in normal law, the airplane's flight management computers would have acted to prevent such a high angle of attack, in alternate law this did not happen. (Indeed, the switch into alternate law occurred precisely because the computers, denied reliable speed data, were no longer able to provide such protection - nor many of the other functions expected of normal law).[28] The wings lost lift and the aircraft stalled.[9]
At 02:11:40 UTC, the captain re-entered the cockpit. The angle of attack had then reached 40 degrees, and the aircraft had descended to 35,000 feet with the engines running at almost 100% N1 (the rotational speed of the front intake fan, which delivers most of a turbofan engine's thrust). The stall warnings stopped, as all airspeed indications were now considered invalid by the aircraft's computer due to the high angle of attack.[29] In other words, the aircraft was oriented nose-up but descending steeply. Roughly 20 seconds later, at 02:12 UTC, the pilot decreased the aircraft's pitch slightly, air speed indications became valid and the stall warning sounded again and sounded intermittently for the remaining duration of the flight, but stopped when the pilot increased the aircraft's nose-up pitch. From there until the end of the flight, the angle of attack never dropped below 35 degrees. From the time the aircraft stalled until it impacted with the ocean, the engines were primarily developing either N1 100% or TOGA thrust, though they were briefly spooled down to about N1 50% on two occasions. The engines always responded to commands and were developing in excess of N1 100% when the flight ended.
The flight data recordings stopped at 02:14:28 UTC, or 3 hours 45 minutes after takeoff. At that point, the aircraft's ground speed was 107 knots, and it was descending at 10,912 feet per minute. Its pitch was 16.2 degrees (nose up), with a roll angle of 5.3 degrees left. During its descent, the aircraft had turned more than 180 degrees to the right to a compass heading of 270 degrees. The aircraft remained stalled during its entire 3 minute 30 second descent from 38,000 feet[30] before it hit the ocean surface at a speed of 151 knots (280 km/h), comprising vertical and horizontal components of both 107 knots. The aircraft broke up on impact; everyone on board died, presumably instantaneously.[31]