Ash Cloud-General Aviation Science Based Decision Making ?

As some of you have seen, I have taken a particular interest in the current ash cloud over Europe mostly because to the outsider like myself, it really looks like the decision to shut down the whole European airspace is not based on real science. Here are some of the issues that bother me:

• Several airlines have flown some of their planes with no problems (i.e. they have checked the inside of the combustion chamber of their planes and seen no issues it seems). These airline planes do not have the capability to really sample the part of the sky they went through.
• I haven't heard any of the airplane and engine manufacturers communicating on these issues.
• The VAAC is producing maps based on models. However complete these models are, very little seems to be done with regards to comparing the results of these models and actual in-situ observations.
  
• I have not seen any convincing evidence from any of the satellite photos (the includes ENVISAT) that we know really where the cloud is altitude- and concentration-wise. Let me be more specific. The European Space Agency has a system in place where the data from satellites are being sent to the VAACs through an SO2 alert list:
  

  ... In addition to VAACs, the information – derived from the SCIAMACHY instrument on ESA’s Envisat, GOME-2 and IASI on MetOp, OMI on EOS-Aura and AIRS on Aqua – is delivered to volcanological observatories, health care organisations, scientists, etc.
  
  
  

  Cloud-free snow-covered Iceland 22 February

  To know whether aircraft may safely pass under or over volcanic ash clouds and to forecast better the future motion of the clouds, the VAACs need more accurate information on the altitude and vertical size of an ash plume.

  This is the main focus of ESA’s Support to Aviation for Volcanic Ash Avoidance (SAVAA) project which aims to set up a demonstration system able to ingest satellite data and meteorological wind fields, in order to compute the injection height profile of volcanic emissions, using trajectory and inverse modelling. The system can then be implemented into the operational environment of the VAACs.

  Furthermore, the SAVAA project is providing complementary data to the SACS SO₂ alerts by developing volcanic ash alert services for VAACs based on satellite data measured in the infrared part of the spectrum.,,,

  while the SO2 concentration is interesting, one notes the different level of coverage and one wonders how the different maps are being reconciled (between different instruments). One also wonders how these maps are being integrated into the graphics of the VAACs because I don't see a reasonable connection between those and these:

And so, I am eventually curious as to how the current process that closes the airspace of an entire continent is really science based. I am looking for any information where field data are in fact reconciled with satellite data.