Calibration of flow angularity sensors forms a very significant part of the flight tests carried out on a new aircraft. This paper describes the advanced parameter estimation techniques adopted for calibrating these sensors on Tejas. Flight path reconstruction procedures have been used to reconstruct the flight trajectories and compute the free stream Angle of Attack and Angle of Sideslip. The errors between measurements and the free stream values are then modeled. Optimization techniques are used to estimate the free parameters of the models to minimize the error. Flight data collated over a large number of maneuvers on seven different aircraft configurations have been used simultaneously. The results of the calibrations have been very consistent and typical results are presented in this paper.