Abstract: There now exists a discrepancy between the practical flight altitude and the one calculated by CFP(Computerized Flight Plan),which is unfavorable to security as well as cost-saving of flights.Along air route,flight altitude discrepancy is variable between segments.According to this character,this paper studies the flight altitude discrepancy based on air route segmentation.The study applies the weighted Fisher ordinal samples cluster method to cluster around those air route points with similar discrepancy level,meanwhile keeping their original order in air route,consequently carrying out air route segmentation.The out come cantell on which air route segments the discrepancy is striking and needs to be given special at tention,which is of benefit to improve the rationality of flight plan(takeoff fuel) and helps pilots support takeoff preparation.

Key words: flight operation and control management, Computerized Flight Plan(CFP), flight altitude, Fisher Ordinal Cluster, Optimal Partition Method