The introduction of precision approaches using low-cost GNSS systems is leading to the replacement of ILS. Providing the required accuracy with GNSS normally requires only a low-power omnidirectional augmentation signal to be broadcast from the airport, which is dramatically less expensive than the multiple, large and powerful transmitters required for a full ILS implementation. By 2015, the number of US airports supporting ILS-like LPV approaches exceeded the number of ILS systems,[1] and this is expected to lead to the eventual removal of ILS at most airports.