FOR HYPERSONIC ATMOSPHERIC ENTRY MISSIONS CHARRING ABLATORS ARE OFTEN USED. THESE MATERIALS ARE MADE OF NON-PYROLYZING MATRICES (CARBON CERAMIC ETC.) COMBINED WITH PYROLYZING MATERIALS (PHENOLIC SILICON RESIN). PYROLYSIS IS THE PROCESS IN WHICH THE POLYMER GRADUALLY CARBONIZES AT HIGH TEMPERATURE LOSING MASS AND GENERATING PYROLYSIS GAS. ONCE GENERATED INSIDE THE MATRIX THE GAS IS EXPELLED AT THE SURFACE CHANGING THE CHEMICAL COMPOSITION OF THE BOUNDARY LAYER AND INFLUENCING THE THERMAL CONDUCTIVITY. THE MATERIAL MODELS CURRENTLY USED FOR DESIGNING AVCOAT THERMAL PROTECTION SYSTEMS (TPS) ARE BASED ON MODELS THAT HAVE BEEN DESIGNED DURING THE APOLLO ERA. ALTHOUGH THEY HAVE BEEN UPDATED TO BETTER REPLICATED THE BEHAVIOR OF MODERN-DAY AVCOAT SUCH AS THE ONE USED ON ORION THEY REMAIN VERY SIMILAR TO THE ORIGINAL. THOSE MODELS PERFORM WELL ENOUGH TO PROVIDE ANALYSES LEADING TO SUCCESSFUL MISSIONS BUT THEY COULD BENEFIT FROM BEING UPDATED. FOR INSTANCE THE PYROLYSIS GAS FLOW IS NOT TAKEN INTO ACCOUNT LEADING TO UNCERTAINTIES IN THE BOUNDARY LAYER EFFECTS AND IN THE CONVECTIVE TRANSPORT AT THE SURFACE. MOREOVER CERTAIN PHENOMENA SUCH AS A MYSTERIOUS "HUMP" THAT APPEARS IN THE DATA AND THAT HAS BEEN ATTRIBUTED TO THE PRESENCE OF WATER IS NOT MODELED AT ALL. FINALLY REACTION KINETICS AT THE SURFACE OFTEN ASSUME CHEMICAL EQUILIBRIUM WHICH PROVIDES GOOD RESULTS IN CERTAIN REGIMES BUT ERRATIC BEHAVIOR IN OTHER (THE SO-CALLED END GAME EFFECT). THE CURRENT PROPOSAL AIMS AT USING A STATISTICAL APPROACH TO REDESIGN FROM THE GROUND UP THE AVCOAT MATERIAL MODEL CURRENTLY USED BY NASA. USING UNCERTAINTY ANALYSIS THE EXTENSIVE AVCOAT ARC-JET DATA WILL BE THOROUGHLY ANALYZED AND USED TO ESTIMATE THE BEST SIMULATION PARAMETERS. THIS NEW MATERIAL MODEL WILL THEN BE APPLIED TO THE EFT-1 FLIGHT DATA AND ITS ACCURACY WILL BE ASSESSED. AN INVERSE PROBLEM APPROACH WILL ALSO BE USED ON THE FLIGHT DATA ITSELF TO ESTIMATE THE TRANSMITTED HEAT FLUX FROM THE AEROTHERMODYNAMIC HEATING. THIS WILL THEREFORE ALLOW FOR A FULL ESTIMATE OF THE ACCURACY OF THE BOUNDARY LAYER APPROXIMATIONS USED IN THE HYPERSONIC COMPUTATIONAL FLUID DYNAMICS (CFD) CODE TO RECONSTRUCT THE FLOW FIELD.