Terrain Awareness And Warning System (TAWS) Envelope Analysis And Safety Analysis

Terrain Awareness and Warning System(TAWS)can improve flight safety through prevention Controlled Flight into Terrain(CFIT).It mainly receives the flight data from aircraft airborne system sensors.And it compares the flight date with warning envelope threshold stored in internal warning computers.If the flight data exceeds the threshold,visual and aural warnings will be provided to alert the pilot to carry out avoid operation and help the pilot to escape danger.The setting of warning envelope is the fundamental problem of the whole TAWS.The study of effectiveness and accuracy of aircraft airborne system input data is an important method to improve the warning performance.This paper focuses on three parts with TAWS as the research object: the study of TAWS envelope,the influence of pilot factors on TAWS envelope and the impact of information fusion on TAWS safety.First of all,the pilot reaction model is proposed to study pilot factors learnt from the mature models,such as OODA.This model introduced the external factors such as height on the basis of delay time's wave characteristics to complete the simulation of pilot reaction model.Combined with a more comprehensive,reasonable and coupling six-degree of freedom model.On this basis,the research was carried out on generating TAWS envelope.The TAWS envelope was obtained from warning avoid trajectory model,through parameterization,simulation setting,curve-fitting and so on.Second,from the perspective of the pilot factor,the analysis of its influence on security of TAWS was performed.Combined with pilot operation during avoid process,three elements,pilot delay time,joystick operation speed,and throttle operation speed,were considered to get the TAWS envelope under different rate.The results were compared with original results to obtain the influence of the pilot factors on TAWS envelope safety.Finally,the impact of information fusion on TAWS security was analyzed through simulation.Information fusion considers TAWS input sensors,and with GPS and ADC as the main research objects,the failure and system noise were analyzed to establish more accurate data model.Then using fusion mechanism,such as weighted average,data from multi sensors were fused.In the TAWS digital simulation system simulation platform for test,the simulations were carried out to gather the alarm mode,the alarm time,the alarm successful rate and so on.Combined with the experimental data,the analysis of the input data before and after fusion influence on TAWS safety was made to reach the conclusion of fusion impact on security.