Interscan proved to have many advantages over other precision landing systems. It allows a wide selection of channels to avoid interference with other nearby airports; has excellent performance in all weather; and gives freedom to locate antennae anywhere at an airport. Some installations became operational in the 1990s and more were set up subsequently in Europe. NASA has operated a similar system to land space shuttles. However, Interscan has not become widely deployed worldwide, largely because the US Federal Aviation Administration has developed the Wide Area Augmentation System (WAAS), which augments the satellite-based Global Positioning System (GPS). Although WAAS is cheaper and conforms to ILS Category I, its accuracy is under 1.0 metre laterally and under 1.5 metres vertically, which is a particular concern at locations that frequently suffer from low visibility.