AIRCRAFT AEROSERVOELASTIC MODELS ARE TYPICALLY CHARACTERIZED BY SIGNIFICANT LEVELS OF MODEL PARAMETERUNCERTAINTY. IN AN ATTEMPT TO MITIGATE THIS FLIGHT DATA CAN BE USED ONLINE TO TUNE A MODEL AND HELP TO IMPROVE ITS ACCURACY OVER A WIDER RANGE OF OPERATING ENVIRONMENTS. THIS TUNING AND ADAPTION PROCEDURE HAS BECOME AN ACCEPTED AND NECESSARY STEP IN MAKING MODELS MORE RELIABLE BUT CANNOT HANDLE OR ELIMINATE ALL UNCERTAINTY. FOR AIRCRAFT THAT OPERATE IN TRANSONIC REGIMES AEROELASTIC BEHAVIOR IS AFFECTED BY THE PRESENCE OF SHOCK WAVES AND THE RESULTING HIGHLY NONLINEAR FLOW FIELD [1 2]. THEREFORE THERE ARESTILL CONCERNS SUCH AS NONLINEAR UNSTABLE AERODYNAMICS WIDELY VARYING OPERATING ENVIRONMENTS AND OTHER PERTURBATION SOURCES THAT CONTRIBUTE TO UNCERTAINTY THAT CANNOT BE AIDED BY COMPARISON WITH FLIGHT DATA. USING AN AIRCRAFT MODEL IN CONDITIONS THAT CREATE EXCESSIVE UNCERTAINTY TO MAKE CONTROL DECISIONS CLEARLY HAS SIGNIFICANT SAFETY IMPLICATIONS. EFFORTS MUST BE MADE TO FURTHER REDUCE UNCERTAINTY TO MANAGEABLE LEVELS IN ALL FLIGHT CONDITIONS.