At 2 h 10 min 05, the autopilot then the auto-thrust disconnected and the PF said “I have the controls”. The aeroplane began to roll to the right and the PF made a nose-up and left input. The stall warning triggered briefly twice in a row. The recorded parameters showed a sharp fall from about 275 kt to 60 kt in the speed displayed on the left primary flight display (PFD), then a few moments later in the speed displayed on the integrated standby instrument system (ISIS). The flight control law reconfigured from normal to alternate. The Flight Directors (FD) were not disconnected by the crew, but the crossbars disappeared.
Note: Only the speeds displayed on the left side and on the ISIS are recorded on the FDR; the speed displayed on the right side is not recorded.
At 2 h 10 min 16, the PNF said “we’ve lost the speeds ” then “alternate law protections. The PF made rapid and high amplitude roll control inputs, more or less from stop to stop. He also made a nose-up input that increased the aeroplane’s pitch attitude up to 11° in ten seconds.
Between 2 h 10 min 18 and 2 h 10 min 25, the PNF read out the ECAM messages in a disorganized manner. He mentioned the loss of autothrust and the reconfiguration to alternate law. The thrust lock function was de-activated. The PNF called out and turned on the wing anti-icing.
The PNF said that the aeroplane was climbing and asked the PF several times to descend. The latter then made several nose-down inputs that resulted in a reduction in the pitch attitude and the vertical speed. The aeroplane was then at about 37,000 ft and continued to climb.
At about 2 h 10 min 36, the speed displayed on the left side became valid again and was then 223 kt; the ISIS speed was still erroneous. The aeroplane had lost about 50 kt since the autopilot disconnection and the beginning of the climb. The speed displayed on the left side was incorrect for 29 seconds.