The microwave scanning beam landing system (MSBLS) was a Ku band approach and landing navigation aid used by NASA's space shuttle. It provided precise elevation, directional and distance data which was used to guide the orbiter for the last two minutes of flight until touchdown. The signal was typically usable from a horizontal distance of approximately 28 km and from an altitude of approximately 5 km (18,000 feet).
MSBLS installations used by NASA had to be certified every two years for accuracy. From 2004, the Federal Aviation Administration worked with NASA to execute this verification; previously, only NASA aircraft and equipment were used. Testing of the Kennedy Space Center's MSBLS in 2004 revealed an accuracy of 5 centimeters.
The shuttle landing approach started with a glide slope of 19 degrees, which is over six times steeper than the typical 3-degree slope of commercial jet airliners.
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- John F. Hanaway & Robert W. Moorehead (1989). NASA SP-504: Space Shuttle Avionics System.
- NASA White Sands Test Facility Launch and Landing Support - Navigational Aids. Retrieved 2004-11-12.
- Federal Aviation Administration Aviation Systems Standard, NASA Program Office AVN-7. Retrieved 2004-11-12.