Originally Posted by
tubby linton
It also seems strange that multiple probes were affected without other probes(pitots) also being blocked.
Not that strange, unfortunately.
In the absence of a fault within a specific component which leaves it vulnerable (for example, a defect resulting in a blocked drain on a specific component), then the scenario is of a "common cause" environmental condition which defeats the design of the vanes. Basically, the conditions are more severe than what the vanes were designed for, or what they can in practice cope with. In which case, barring small variations in performance between the components (as is normal) it's not surprising that the same conditions would defeat all of the installations at once.
Similarly, since it is likely a function of the specific design (and design requirements) it also would not be a surprise that a specific component (say an AOA vane) was vulnerable to a set of conditions that other components could cope with. (Even if all designed to the same requirements, it wouldn't be unusual for them to have different capabilities - some might barely meet the requirement, some might have lots of margin)