How is LAAS different than WAAS?
A. Like the Wide Area Augmentation System (WAAS), LAAS relies on GPS for basic navigation signals. However, with WAAS, GPS-corrected navigation signals come from space, broadcast from WAAS geostationary satellites. With LAAS, the GPS-corrected navigation signal is broadcast from a LAAS VHF data broadcast transmitter at or near the airport. Although LAAS and WAAS will operate independently, LAAS will complement WAAS by providing GNSS Landing System (GLS) landing service for Category II/III precision approach operations. LAAS will also provide GLS Category-I capability at locations where WAAS service may not be available. Other differences between WAAS and LAAS include the manner in which the availability of the systems are computed, the manner in which avionics receive information on approach procedures, and the vertical alert limits (VAL) associated with each system.
