Research On Safety Risk Of Aircraft Wake-Vortex In Approaching Phase

The proportion of the air transport industry in the entire transportation industry continues to increase and the flow of air traffic is increasing day by day.The wake vortex of the aircraft is an important factor restricting aviation safety,especially in approaching phase.In the meantime,the safety problems caused by it should not be underestimated.Therefore,it is necessary to study the wake turbulence evolution mechanism in depth and put forward a calculation method of the safe dynamic wake separation that can ensure the flight safety of aircraft during normal operation.We should also comprehensively identify the causes of wake vortex accidents from a system perspective and analyze their interaction mechanism.Then the direct causes and deep root causes of the accident can be explored.What’s more,wake vortex safety risk can also be analyzed.In this paper,the wake turbulence safety risks in approaching phase are studied comprehensively and systematically from both micro and macro perspectives.Microscopically,the wake vortex characteristics and internal evolution mechanism in approaching phase are analyzed.The classical wake vortex induced velocity models are simulated and analyzed.Based on the wake vortex data measured in the actual airport during the approaching phase,an accurate wake dissipation model is established.The wake encounter model is established by selecting the measurement index of the severity of wake encounter.The mechanism of wake accidents is analyzed from the physical microscopic point of view.Then,the paper explore the direct causes of wake accidents,and propose the calculation method of dynamic safety wake vortex separation.Macroscopically,this paper uses mathematical statistics to summarize and analyze the accidents caused by aircraft encountering wake turbulence in recent years at home and abroad.Fault Tree Analysis(FTA)can be used to determine the factors causing wake accidents and analyze the minimum cut set and minimum path set of the model qualitatively in order to discriminate the accident paths.Based on the above analysis results,Bayesian network model(BN)of wake accidents is constructed.The prior probability and conditional probability of each basic event are determined based on the expert scoring-fuzzy set theory.The posterior probability of each basic event is verified by Netica simulation software,and then three basic event importance are tested and calculated.We can determine the risk factors and system weaknesses that have the greatest influence on wake vortex accidents in order to identify the external risk factors that lead to wake vortex encountering events from the overall system perspective.Finally,Vensim software is used to build a systematic wake encounter risk dynamic analysis model for the man-management system which has the greatest impact on accidents based on FTA-BN analysis results and system dynamics(SD)theory.Causality analysis is carried out after sub-systems are divided,and a system dynamic flow diagram is established to clarify the causality,feedback structure and dynamic evolution of risks with time in the system so as to implement the research of unsafe event occurrence mechanism.By adjusting policy variables,the influence of risk factors on wake accident risk level is analyzed,and then a theoretical reference for the formulation of safety policies can be provided for managers.