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Aerodynamic database update from the flight tests using system identification techniques is a crucial tool for the development of control laws and high fidelity simulators. For the certification of aircraft under test, aero-database needs to be validated from flight tests throughout the flight envelope and also to certain levels beyond the envelope boundaries. Validation of aero-database close to envelope boundaries entails additional complexities which necessitates careful handling of flight data identification and update process. This paper discusses the approach adopted for aero-database update and flight clearance, followed by a discussion on the issues relevant in the extreme flight test regimes, such as, flow angle accuracy at higher angles-of-attack, center-of-gravity variation with fuel pitch angle for high-g maneuvering conditions and inaccuracies in Mach number at transonic speeds.

This paper presents the implementation of flight path reconstruction (FPR) and wind estimation techniques applied to a high performance fighter aircraft. The analysis is carried out for the flight test data gathered and stored in a Crash Data Recorder (CDR). The data signals obtained from CDR are generally highly noisy, with frequent data drop outs and also with low sampling rate. The estimation technique applied for data reconstruction is the extended Kalman filtering (EKF). The reconstructed trajectories can be compared with the actual flight trajectories such that, in case of unavailability of data from other sources (e.g., digital flight control computer), the algorithm should be able to reconstruct the trajectories with the minimum set of data available from the CDR. Wind estimation along with the trajectory reconstruction can give better accuracy in airspeed as well as flow angles.