The Wide Area Augmentation System (WAAS) is an air navigation aid developed by the Federal Aviation Administration to augment the Global Positioning System (GPS), with the goal of improving its accuracy, integrity, and availability. Essentially, WAAS is intended to enable aircraft to rely on GPS for all phases of flight, including precision approaches to any airport within its coverage area.
WAAS uses a network of ground-based reference stations, in North America and Hawaii, to measure small variations in the GPS satellites' signals in the western hemisphere. Measurements from the reference stations are routed to master stations, which queue the received Deviation Correction (DC) and send the correction messages to geostationary WAAS satellites in a timely manner (every 5 seconds or better). Those satellites broadcast the correction messages back to Earth, where WAAS-enabled GPS receivers use the corrections while computing their positions to improve accuracy.
The International Civil Aviation Organization (ICAO) calls this type of system a satellite-based augmentation system (SBAS). Europe and Asia are developing their own SBASs, the Indian GPS Aided Geo Augmented Navigation (GAGAN), the European Geostationary Navigation Overlay Service (EGNOS) and the Japanese Multi-functional Satellite Augmentation System (MSAS), respectively. Commercial systems include StarFire and OmniSTAR.
Read more about Wide Area Augmentation System: Operation, History and Development, Comparison of Accuracy, Benefits, Drawbacks and Limitations
Famous quotes containing the words wide, area, augmentation and/or system:
“Under the wide and starry sky,
Dig the grave and let me lie.
Glad did I live and gladly die,
And I laid me down with a will.
This be the verse you grave for me:
Here he lies where he longed to be;
Home is the sailor, home from sea.
And the hunter home from the hill.”
—Robert Louis Stevenson (1850–1894)
“Self-esteem is the real magic wand that can form a child’s future. A child’s self-esteem affects every area of her existence, from friends she chooses, to how well she does academically in school, to what kind of job she gets, to even the person she chooses to marry.”
—Stephanie Martson (20th century)
“He does smile his face into more lines than is in the new map with the augmentation of the Indies.”
—William Shakespeare (1564–1616)
“Television is an excellent system when one has nothing to lose, as is the case with a nomadic and rootless country like the United States, but in Europe the affect of television is that of a bulldozer which reduces culture to the lowest possible denominator.”
—Marc Fumaroli (b. 1932)