As I am a teacher in the subject, it would be interesting to know which stance
the current QB has.
Our studyguide maintains that a blockage of the ram
air opening of a pitot tube will cause the ASI to freeze at current speed
whereas in real life, such a blocking would cause the ASI to read 0 because of
pressure escaping through the waterdrain.
If you teach the subject then why do you not know the answer!
The water drain is sealed, otherwise there would be a permanent loss of pressure.