Before GPS, approach classifications were cut and dried–they were either precision (ILS) or nonprecision approaches. But as pilots move into the future, they will need, before considering an approach into an “obstacle-rich environment,” to first navigate through an acronym-rich environment of new terminology to decide how to reach the threshold. Attendees at the FAA’s twice-yearly Satellite Operational Implementation Team (SOIT) meeting last month were briefed on a new series of approach classifications planned for use when the GPS wide-area augmentation system (WAAS) enters operational service.
For a precision approach, there will be three supporting technologies: ILS, WAAS and LAAS. WAAS is intended to be the prime, continental U.S. (Conus)-wide GPS Category I precision approach aid, with LAAS Cat I planned for around 46 locations, such as in mountainous areas, where the accuracy correction signals from the WAAS geostationary satellites may not be fully reliable. But since WAAS won’t be able to support better than Cat I approaches, the FAA also plans to colocate 114 LAAS Cat II and III systems with present ILS Cat II and III installations.
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