New version of the spread sheet with more data.
No Altitude until the alt kicks in passing 425' on departure at 11:21z and then the data shows a steady climb.
A series of climb data points indicating 1200 - 1500 feet until a maximum of 1900 at 11:22z. The transponder remained squawking 1571 and didn't ever change through the whole flight. There were several data missed captures with no squawk or time code but altitude was read
Climb continued but with great amounts for time hack discards and replaced by SOV073. There are fairly regular misreads from single data points usually indicating spurious altitude in the teens and as erroneous as FL290. These were individual points
By 11:25z it was operating or or near 6000' but climb continued.
11:26z 6700' drifting back down to 6000' but continuing descent.
VSI data show the usual odd, individual rogue numbers slipping in as I'd expect but the climb 6000 to 6700 has rates suggesting it had been cleared higher. However the descent rate becomes pronounced but leaping from sample to sample from positive to negative numbers in the course of a single second of data.
The attempt to level again at 6000 dips below and here the time hacks are more regular suggesting there's a fair bit of heave ho going on to reach 6000 from 5800' and continues up to 6275'.
The aircraft remains around that altitude for about 5 seconds but the pitch to regain 6000' and remain there is very brief and returns to descent and remains that way until the lowest recorded 2475' and beyond. Below 4900 feet there are no time stamps at all but the claimed vsi data is very extreme.
I've taken the time to describe this in words so that pilots can analyse what was happening and run it through the things they've experienced in the sim over the years.
The pretty illustrations while dramatic are compressed and don't show the data we see in the time periods we have to analyse and react.
Rob