Hi,
Due to the way Pitot or Pitot-static tubes are usually mounted, they are prone to collecting ice crystals. Encountering high concentrations of ice crystals may lead to blocked Pitot or Pitot-static tubes because the energy necessary to melt the ice crystals can exceed the tube heating system capability, or the water formed by the melting process is not completely evacuated and it can re-freeze downstream inside the tube. Pitot or Pitot-static tube blockage can lead to errors in measuring airspeed.
Nothing to say about all this .. apart from the publication date ...
23/03/2011 
So it took years (nearly half a century if we take into account the advent of the jet) to account for this phenomenon ...
Edifying has more than one way
Will be not astonished if one day EASA publish a notice about the "discovery" of the wheel ...