Originally Posted by
notfred
They knew they had lost air speed indication, but from this comment I think they believed that they had a static system problem. This could lead them to discount the altimeter showing the climb and loss of height in the stall. Whilst I've learnt from the AF447 threads that the vertical speed indication is inertial based, is this something that they would know / remember under duress?
For a start, it's only the PF who says that (at 2:11:58) - the PNF and Captain make no reference to it at all, so there was no agreement and therefore no "they".
By that point they indeed had a problem with data coming from the static ports, in that the airflow around the static ports was being fouled by the "mushing" stall descent profile, thus causing erratic VS readings (see the DFDR VS profile for 2:11:58), and at that point the reading was more-or-less off the scale.
I'm pretty sure that covered static ports tend to report varying altitudes around a certain range, as in the Aeroperu case. I've yet to hear of a static port failure that resulted in a steady, unwinding altimeter that appears to have been the case with AF447, and I'd hazard the opinion that whether you trust the static ports or not, with an altimeter unwinding at approximately 10,000ft/minute it's better to err on the side of caution and take it seriously!