Originally Posted by
Ian W
It was recorded the thin trace - then someone 'computed' a different trajectory smoothing where changes were not thought realistic.
Yes and no; let me explain what was done and why:
1) The thin trace is recorded pressure altitude, and yes, I didn't think it looked realistic.
2) What I did wasn't smoothing; I first took recorded vertical speeds prior to upset and used those to calculate altitudes (starting at 28000 feet). The calculated altitudes matched recorded altitudes to within a few tens of feet - prior to upset.
3) Considering that a success, I did the same from upset onwards. Now the calculated altitudes did
not match recorded altitudes, and the new plot is, yes, surprisingly smooth.
The first problem with the recorded barometric altitudes post upset is that they bear no relation to the recorded vertical speeds. That "zoom climb" for instance takes place while VS is (very) negative.
Secondly, the altitude changes over time for the first "climb" works out to a VS of 95280 fpm or 488 m/s, followed by a descent at -187800 fpm or -955 m/s (M3.15). If the transition was linear, the plane pulled -42G there. And something similar happened another nine times over the next twenty seconds.
That's just not believable, is it? I'm just some random dude on the internet though, so if you don't think my calculations can be trusted either, that's fine.