Radio Beacon Landing System (RMS)

This was the prime navigation aid for final approach and landing, providing azimuth and elevation data from an altitude of about 7 km. The RMS was a standard all­weather scanning-beam microwave landing system (MLS) similar to those adopted for civil aircraft in the early 1980s by the International Civil Aviation Organization. In microwave landing systems antennas located on the ground transmit a reciprocat­ing beam to an aircraft, while the aircraft measures the interval between a pair of received beams and thereby determines the azimuth and elevation angle. Buran was equipped with three RMS sets (17M901) each containing a transmitter/receiver and a decoder (34.5 kg). The ground-based component incorporated an azimuth and elevation antenna on either side of the runway, providing azimuth coverage of about 30 degrees from the runway centerline and vertical guidance up to 30 degrees. The antennas had a much greater range (at least 25 km) than traditional aviation micro­wave landing systems.

The RMS was very similar to the Space Shuttle’s Microwave Scan Beam Landing System (MSBLS). VNIIRA (the All-Union Scientific Research Institute of Radio Equipment), the Leningrad institute that built the system, was criticized by some for not using an advanced aviation microwave landing system called Platsdarm. This was under development at the institute by the end of the 1970s and featured phased-array

antennas with electronic scanning rather than dish antennas with mechanical scanning as in the RMS. Some felt that the simultaneous work on the Buran system and Platsdarm was a wasteful duplication of effort.