Hopefully the data recorders are preserved in the tail.
Can anyone advise the origin of the altitude recorded on the FDR. Pressure only? Or GPS also?
Maybe I am missing something, but it all seems a bit unsatisfactory. We measure a pressure using ports that are subject to problems such as icing. We then take this pressure and derive a flight level based on 1013. However if ambient temp or pressure was to change as you enter a cell (and the chaotic winds within a cell are due to pressure differentials), this would distort any change in FL that was being measured.
I never quite understood this when we got the data for AF447. Obviously there were significant altitude excursions during the upset. But to what extent were there measured excursions corrupted by sudden pressure (or temp) changes.I recall AF447 pilots noted a dramatic increase in OAT shortly before it all went wrong.
Furthermore, could a perceived change in FL cause the automatics to respond so as to correct this, and could this compound the problems due to pitot tube freezing and loss of valid airspeed.
There seem to be a lot of links in the chain between what we measure and what we derive from it.