What does ILS stand for in aviation terms?

ILS stands for Instrument Landing System, which is a crucial component in aviation that assists pilots during the landing phase of flight. The system provides precise guidance to aircraft as they approach a runway, especially under poor visibility conditions. It consists of two main elements: the localizer, which helps with horizontal guidance by indicating the aircraft's position relative to the centerline of the runway, and the glideslope, which provides vertical guidance to ensure that the airplane descends at the correct angle.

The use of ILS enhances safety and allows for more precise landings in challenging weather, significantly reducing the risk of accidents during this critical phase of flight. The other choices you considered do not correspond to standard terminology or practices used in aviation, making Instrument Landing System the correct and relevant term.