The Instrument Landing System (ILS), in its present 90/150 Hz format, had its beginnings
in the United States and England during the years 1939 to 1945. Since then, it has served the
aviation community worldwide. There have been many improvements to cope with ever
increasing traffic, crowded airports, and difficult siting problems. There are those who say
that it's time to replace the system with newer technology; are they right?