@jcjeant
Indeed this can happen.. only if you don't check your airspeed ... (who was under 60 knots) and if you don't know the specifications of your aircraft ...
Anyway .. when you read 60 knots (all parameters indicated that this speed was valid) on the speed indicator of an A330 .. you can deduce two things:
Or you are rolling on ground
Or if you are in the air ... your plane is no more flying .. he is falling like a stone ... (check altimeter)
For airspeed a qualitative 'sanity' check would be Ground Speed from GPS. If both airspeed and ground speed are around 40kts then it supports a diagnosis of stall unless you believe in 300kt wind. To that end the PAX could have seen the GPS speed decay from 400kts to 40kts in the GPS in the seat back - very sad.
The PF had less than 2 years ATPL, I recall his wife was on board. Perhaps many with similar training/experience would do the same or worse in this nightmare scenario. The ultimate responsibility lies with the capt.