Definition
A category of GPS augmentation systems that use a network of ground reference stations and geostationary satellites to broadcast correction and integrity information to GPS receivers, improving accuracy, availability, and trustworthiness of position data for navigation. Different regions operate their own SBAS: WAAS in the United States, EGNOS in Europe, MSAS in Japan, and GAGAN in India.
Plain English
SBAS is the general name for satellite-based systems that fix small errors in GPS signals and warn pilots if the signal becomes unreliable. WAAS is the U.S. version of SBAS; other countries run their own.
Context Anchor
Seen in advanced navigation, WAAS, and instrument approach discussions when the handbook explains how GPS accuracy and reliability are improved for aircraft use.
Derivation
Satellite-Based describes how the corrections are delivered — from geostationary satellites overhead. Augmentation comes from the Latin augmentare, meaning to increase or add to. The system adds something to raw GPS: corrections and integrity warnings that the basic GPS signal does not provide on its own.
Why Pilots Care
It enables precise vertical guidance on approaches without local ground stations, expanding safe access to more airports in low-visibility conditions.
Intuition Check
Do not think of SBAS as a separate navigation system that replaces GPS. It is an added support system that improves GPS signals and helps warn the receiver when the information is not reliable.
Example Sentence 1
The avionics manual noted that the GPS receiver was certified to use any compatible SBAS signal, including WAAS in North America and EGNOS over Europe.
Example Sentence 2
During the en route phase the pilot confirmed SBAS integrity before descending into the terminal area.