Methodology for Assessing Shortened ILS LOC and GP Critical Areas: an Example of Gorno-Altaisk Aerodrome

Abstract

Based on the analysis of recommendations of the International Civil Aviation Organization on a reasonable reduction in sizes of ILS critical areas and identification of shortcomings of the existing requirements of the Russian Federal Aviation Regulations for critical areas of ILS localiser and glide path (glide slope), a procedure has been developed that allows assessment localiser and glide slope bends for shortened critical areas. The assessment comprises the influence of different reflecting objects situated on operation area of the aerodrome, as well as of aerodrome environs on the operation of the ILS localiser and glide path.Reflecting objects can be approximated by models of a wall (that simulates reflections from buildings, bridges, fences), of a cylinder (that simulates reflections from factory pipes, tanks, containers, aircraft fuselages) and of a hemispherical diffuse reflector (simulates reflection from elevated terrain).The procedure was tested for Gorno-Altaisk aerodrome, and aproposal was developed to reduce the critical area of the localiser, which will expand the apron by 35 m, eliminate problems with imposed speed limits and blocking movement of aircraft on the taxiway. Also, the probability of service failure will decrease by 3…11 times, and the runway occupancy time will decrease by 12,5…26 % compared to existing features.