Evaluation of the Performance of a Synthetic Sensor for Angle of Attack and Sideslip Estimation

In-flight loss of control, often caused by an excessive angle of attack, is the leading cause of fatal accidents in commercial aviation. Accurate monitoring of aerodynamic angles is crucial for maintaining aircraft stability, particularly during critical phases such as take-off and landing. The European Union Aviation Safety Agency (EASA) has recently considered the use of synthetic sensors as a form of analytical redundancy, reducing the need for additional hardware. The Angle of Attack and Sideslip Estimator (ASSE) was developed as a synthetic sensor to provide this redundancy by processing existing onboard data to assess aerodynamic angles, thereby eliminating the necessity for dedicated hardware when wanting to verify the correct functioning of the already existing sensors. Previous studies have validated the estimator through numerical simulations and tests in relevant environments. This thesis, conducted in collaboration with Civitanavi Systems by Honeywell, advances the research by evaluating two key aspects: the effect of input noise on the estimator’s accuracy and the use of real flight data to assess its practical applicability. The thesis is organized into distinct chapters. It begins with an introduction to the topic of aerodynamic angles, highlighting the importance of precise measurement and redundancy in ensuring flight safety. Subsequently, the concept of analytical redundancy is introduced, with a focus on its application in flight data estimation. In the following chapter, the functionality of the ASSE is presented in detail, outlining its role in estimating the angle of attack and sideslip without requiring additional physical sensors. A performance assessment is then conducted using simulated data to verify the operation of the synthetic sensor, focusing on its sensitivity to input noise. The input noise is analyzed separately, with each onboard sensor’s noise contribution examined to understand its impact on the estimation of aerodynamic angles. Finally, real flight data provided by Civitanavi Systems by Honeywell is introduced. These data include a series of flight maneuvers. The raw data is pre-processed using a low-pass filter to remove high-frequency noise and ensure the reliability of the input signals. After filtering, the aerodynamic angles are estimated and analyzed to evaluate the ASSE’s performance under real-world conditions.