Analysis Of Precise Approach Stage Obstacle Assessment Methodological Study

The control of obstacles near the airport plays an indispensable role in ensuring the safe and efficient operation of the aircraft.In recent years,China has built a large number of high altitude airports,and its runway length exceeds the Obstacle Assessment Surface(OAS)specification.The upper limit,while ICAO’s regulations on such situations are more general,it is necessary to demonstrate its security;in addition,the contradiction between clearance protection and urban construction is increasingly prominent,while the current OAS is more conservative,so it is necessary to improve the risk assessment of obstacles.method.Firstly,the Collision Risk Model(CRM)was used to screen out the point where the collision risk probability is 1×10~-77 at the specified position of the precision approach segment,and the ellipse evaluation was used to construct the obstacle ellipse evaluation surface(OAS is its cut plane);and studied the relationship between OAS and elliptical evaluation surface under the premise of increasing airport elevation,based on the safety of OAS applied to the long runway of the high altitude airport.Then,the probability distribution characteristics of the track deviation in the precision approach phase were studied.The Monte Carlo simulation was used to obtain the track deviation when constructing the CRM.Since it did not obey the single Gaussian distribution,the Gauss Mixture Model(GMM)was established and used.The Expectation Maximization(EM)algorithm estimated the parameters of the GMM model to obtain a probability density function with a high degree of fit.Finally,the newly obtained probability density function was used to fit the track deviation of the precision approach segment of Geermu Airport,and a safety assessment model was constructed.The model was used to calculate the collision risk probability of the imaginary obstacle and fit 10-7 at the specified position.Then,based on the probability density function of the actual track deviation,the Monte Carlo method was used again to simulate the collision risk of the long runway obstacles to verify the safety of the safety evaluation model;then compared it with the CRM calculation results.To verify the operational benefits available to the application security assessment model..The above research verifies the safety of the OAS surface in the high altitude airport,and provides a theoretical basis for the rational application of ICAO related specifications.It also proposes the obstacle ellipse evaluation surface and the safety evaluation model to optimize OAS and CRM,respectively.The research results of this paper have certain practical and reference value for airport obstacle assessment and control.