Abstract: In order to improve the obstacle evaluation method in the precision approach segment,a CRM based ellipse evaluation method was proposed.Firstly,the probability of collision risk at each position of the precision approach segment was calculated by CRM,the ellipse fitting dots which risk probability is equal to 1×10^-7 were chosen,and the elliptical evaluation surface was constructed; Then,taking a typical airport as an example,the obstacles ellipse evaluation surface and obstacle assessment surface (OAS) was used to evaluate typical obstacles,and the evaluation results were compared.Finally,CRM was used to verify the reliability of the obstacle ellipse evaluation surface.The results showed that the evaluation results of OAS were conservative.Using the newly constructed obstacles to evaluate the elliptical surface could effectively improve the airspace utilization rate of the airport precision approach segment under the premise of meeting the safe operation.

Key words: aeronautical study, obstacle assessment, collision risk model(CRM), obstacle elliptical assessment surface, precision approach segment