Area Augmentation System (WAAS) is a GPS-based navigation and
landing system that provides precision guidance to aircraft at
thousands of airports and airstrips where there is currently no
precision landing capability. Systems such as WAAS are known as
satellite-based augmentation systems (SBAS). WAAS is designed to
improve the accuracy and ensure the integrity of information coming
from GPS satellites.
The FAA is using WAAS to provide a Lateral Navigation/Vertical
Navigation (LNAV/VNAV) capability. This capability will facilitate
improved instrument approaches to include vertical (glide path)
guidance to an expanded number of airports. Concurrently, the FAA
will evaluate the approach to achieve Global Navigation Satellite
System (GNSS) Landing System (GLS) capability in later years.
WAAS testing in September 2002 confirmed accuracy performance of
1 - 2 meters horizontal and 2 -3 meters vertical throughout the
majority of the continental U.S. and portions of Alaska.
The WAAS signal can also be used for many non-aviation
applications, as well... not that that matters (grin).