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WAAS (Wide Area Augmentation System) GPS is used in aviation primarily to
Choices
increase GPS speed.
Speed isn't the issue; accuracy is.
✓ improve GPS POSITIONAL ACCURACY to within ~3 meters horizontally.correct
vs ~10m for non-WAAS GPS) by broadcasting correction data from ground reference stations via geostationary satellites. enables LPV (Localizer Performance with Vertical guidance) approaches that approximate ILS. WAAS = ground stations measure GPS errors, broadcast corrections via geostationary satellites. Result: ~3 meter horizontal accuracy, ~7 m vertical (vs raw GPS 10+ m). Enables LPV approaches with ILS-equivalent minima at thousands of airports without ILS infrastructure. WAAS-equipped GPS is the modern gold standard for IFR flight in the US.
speed up GPS message transmission.
Message rate isn't the WAAS function.
replace VORs entirely (not yet).
VORs are still in use; some are being decommissioned but not all.
Why
vs ~10m for non-WAAS GPS) by broadcasting correction data from ground reference stations via geostationary satellites. enables LPV (Localizer Performance with Vertical guidance) approaches that approximate ILS. WAAS = ground stations measure GPS errors, broadcast corrections via geostationary satellites. Result: ~3 meter horizontal accuracy, ~7 m vertical (vs raw GPS 10+ m). Enables LPV approaches with ILS-equivalent minima at thousands of airports without ILS infrastructure. WAAS-equipped GPS is the modern gold standard for IFR flight in the US.
FAA source: AIM 1-1-18, AC 90-107; AIM 1-1-18 Wide Area Augmentation Systembrowse the reference library →
Original study question written for this course — representative of FAA knowledge-test topics, not an actual current FAA exam question.