Microwave landing system-a favoured alternative to current ILS

Abstract

The Instrument Landing System (ILS) has been in operation for about four decades. While this system has served aviation well during this period of rapidly growing aircraft traffic, speeds and variety, its limitations have steadily been coming to the forefront. Among its chief drawbacks in the present form are (i) restriction of flight control manoeuverability, (ii) limited landing traffic rates, and (iii) special terrain and siting requirements. With explosive growth in aviation, these drawbacks are being emphasized and a need has been felt in recent years for a more flexible and modern system. In order to overcome the operational and technical problems of US, International Civil Aviation Organisation (ICAO) has formulated guidelines for a futuristic system that will replace the ILS. After evaluating the various systems proposed by different countries, ICA0 has accepted the Time Reference Scanning Beam Microwave Landing System (TRSB-MLS) for world-wide use. This paper reviews the limitations of the current US and presents the salient features of the TRSB-MLS which is on the verge of implementation throughout the world including India. The current year is the originally stipulated ICAO target for operational implementation of the system.