MICROWAVE LANDING SYSTEM (MLS)
Prepared by: Rañon, Johnatan Noveleon G. ECE 52
• all-weather, precision landing system originally intended to replace or supplement the Instrument Landing System (ILS) • provides azimuth, elevation, and distance, as well as "back azimuth“ • used for short-range communications with airport controllers
MLS employs 5GHz transmitters at the landing place which use passive electronically scanned rays to send scanning beams towards approaching aircraft. An aircraft that enters the scanned volume uses a special receiver that calculates its position by measuring the arrival times of the beams.
selection of channels to avoid interference with other nearby airports weather performance in all
"footprint" at the airports
Advantages over ILS
• antennas were much smaller • did not have to be placed at a specific point at the airport • signals covered a very wide fanshaped area off the end of the runway • uses a single frequency, broadcasting the azimuth and altitude information one after the other
• elimination of ILS/FM broadcast interference problems • provision of ail-weather coverage up to ±60 degrees from runway centerline, from 0.9 degree to 15 degrees in elevation, and out of 20 nautical miles (NM) • capability to provide precision guidance to small landing areas such as roof-top heliports
• continuous availability of a wide range of glide paths to accommodate STOL and VTOL aircraft and helicopters • accommodation of both segments and curved approaches; • availability of 200 channels - five times more than ILS • potential reduction of Category I (CAT l) minimums
• improved guidance quality with fewer flight path corrections required • provision of back-azimuth for missed approaches and departure guidance • elimination of service interruptions caused by snow accumulation • lower site preparation, repair, and maintenance costs....
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