Everyone on here is using the altitude deviations at 5000' as being indicative of control issues, I'd say it's most likely due to the pilots having to hand fly the airplane with no flight director while troubleshooting an emergency and preparing to return to the airport. They're very minor altitude deviations, consistent with trying to hand fly an airplane while being distracted with something.
The vertical speed variations are not indicative of normal hand flying. I am seeing pitch changes of 5 degrees to achieve those rates.
This accident is baffling to me, if they did encounter unreliable speed as per the previous sector it should be relatively straight forward in daytime, VMC, in sight of ground with the airport just next to you to recover and land.
I suspect that due to the unreliable speed safety devices for low and high speed activated making the manual control more challenging.
The final moments of this look similar to AF447 with a sudden climb into an undesirable aircraft state that was not recoverable. I remember many critics on this and other places stating categorically that this will never happen in a Boeing because the controls are interlinked and the throttles move.
The old and bold amongst us cautioned that it could happen in any aircraft. The industry went into a program of providing recurrent training to all pilots subsequent to AF447 as it was felt at the time training and awareness was lacking in industry.
This is a very different outcome to the Malaysian A330 that has no airspeed out of Brisbane, at night taking off into a black hole (no horizon or lights at night when taking off to the north).
Human rights lawyers are "ambulance chasers of the very worst kind.'" - Sky News