Definition
A system that improves the accuracy, integrity, and availability of GPS signals by using a network of ground reference stations to monitor satellite errors, then broadcasting correction data to aircraft through geostationary satellites. In the United States, the SBAS implementation is the Wide Area Augmentation System (WAAS).
Plain English
A helper system that watches GPS for errors and sends corrections to your aircraft, making the position information far more accurate and trustworthy than plain GPS alone.
Context Anchor
Pilots encounter SBAS when checking GPS navigation capability, avionics approvals, and instrument approach requirements.
Derivation
Plain GPS by itself is not always accurate or reliable enough for precise approaches. 'Augmentation' means adding something to improve it. SBAS adds a layer of correction delivered from satellites — hence 'satellite based augmentation.'
Why Pilots Care
It enables lower decision altitudes on GPS approaches such as LPV, improves safety margins, and reduces dependence on ground-based navigation aids.
Intuition Check
“Satellite based” does not mean the whole system is only in space. SBAS depends on ground stations as well as satellites.
Example Sentence 1
The aircraft's GPS receiver is SBAS-capable, so the crew briefed the LPV minimums for the approach.
Example Sentence 2
SBAS corrections allowed the navigation system to meet the required accuracy for the RNAV procedure.