A steady state box model was used to calculate instantaneous ozone production rate in the plumes of several major source types observed with the Baylor University aircraft during TexAQS 2000. The model calculations were constrained by the observations collected from the aircraft platform. Results are presented for several source types (power plant, urban, and petro-chemical industrial plumes) under a variety of conditions. Also presented is an analysis of the effect of measurement uncertainties on the results.