Irrespective of IRS failure, autopilot disconnect, FMC position anomaly. . . the crew members lacked elementary survival instinct by not immediately hand flying the airplane, using the independently powered stand by attitude indicator as a primary reference to maintain wings level upon autopilot disconnect warning . . . and furthermore, by not doing so after multiple "bank angle, bank angle" warnings.
This scenario is another classic high altitude high speed upset because nobody was flying the airplane when the autopilot kicked off.
In IMC at FL350, at cruise speed, and especially in stormy weather, there is no time for delay to apply total concentration for one pilot at the controls just to maintain wings level and to hold altitude.
Recurring simulator training with impromptu loss of A/P and instrument displays will re enforce the urgency of manual control before the airplane enters an unrecoverable upset.
