Ignore me I'm sure Takata is correct re facts re location/storm - there was much discussion in previous thread and elsewhere about how quickly you can get down in one piece from 35,000ft, clearly not a gentle 20:1 glideslope?
As stated in the BEA report, pitots on this type of aircraft have a history of problems. The AA probe itself was introduced to replace inferior earlier models, and then early examples had manufacture QC issue with drain hole
http://ftp.resource.org/gpo.gov/regi.../2004_5788.pdf
This earlier incident on an Airbus quantifies the effect of pitot drain hole blockage for the probe in use at that time - is much higher/ faster much different in dynamic pressure?
http://www.aaib.gov.uk/cms_resources...pdf_501829.pdf
So drain hole blockage alone is sufficient to disengage autopilot/ thrust.
Having identical probes makes it easier to detect one outlier - they should all read the same - but why would they then not fail in same way when subject to same ice cloud?