ILS wiki
ILS wiki 2011
ILS instrument landing system is a ground-based instrument access system that furnishes exactness direction to an aircraft landing and approaching on a runway, using a combining of radio signals and, in many cases, high-intensity lighting arrays to change a safe landing during instrument meteorological conditions , such as low ceilings or reduced profile due to fog, rain, or blowing snow.
Use of instrument landing system
Rate-of-descent formula
Decision altitude/height