Pitot Icing
Seems we have a recurring problem with some pitots at high altitude when penetrating the tops of CBs. That problem could well be that when we are penetrating CiroCu/CiroStratus rich in ice crystals at way sub zero OATs we may be converting some of those crystals to water with a heated probe. I would expect that some ice crystals will enter the heated pitot simply because of their inertia.The melted crystals may then be entering the tubing connecting the pitot and refreezing to form a blockage particularly if the drain holes of the pitots are too small or already blocked or partially blocked with crystals.
As a TP I have not had any experience in the flight testing of pitot systems except to determine position errors PEs for pitot static systems. These tests are usually done at as close to sea level as possible and more often are done using a trailing static and a test pitot on a projecting boom.
Does anyone know whether the offending pitots and attendant tubings have been adequately tested under the worst conditions to be expected at high altitude.