it seem to me to be extremely unlikely that three would fail at once, they would likely be from different manufacturing batches.
Actually it seems that the ACARS messages are indicating the failure of just one of the sensors.
That's what is probably still missing in the "clogged pitot tube as a cause" hypothesis.
Correcting:
If the message
341115 –
PROBE –
PITOT actually refers to all probes disagreeing 1+2/2+3/1+3 instead of only two of them in agreement then I stand corrected that all three probes failed.