Tubby, could you be talking about a static port hole in a combined pitot/static probe?
[edited]
Ah, I think I see now... Your "trapped pressure" threw me. I think may have that bit a little skewed.... If the "vent hole" was plugged, but the pitot opening was not, that would lead to a greater pitot pressure, causing a higher a/s reading, until the blockage cleared... but if both were blocked (on the pitots only - static vents still open) your airspeed would only change according to whether you flew up/down/into different pressure air.
Last edited by 3holelover; 10th May 2011 at 14:22.