Which mechanism provides GPS integrity information that can indicate availability?

Which mechanism provides GPS integrity information that can indicate availability?

• A. RAIM
• B. SBAS
• C. GBAS
• D. WAAS

Answer: (D)

Integrity information from a wide-area augmentation system is what lets a pilot know when GPS data can be trusted for use in operations. WAAS provides this kind of integrity data across a large region by processing GPS signals, computing corrections and integrity alerts, and broadcasting them through geostationary satellites. The receiver uses those integrity messages to decide whether the GPS service is available for a given operation (for example, supporting precision approaches like LPV). When WAAS integrity is good, the system indicates availability for the enhanced navigation service; if integrity is degraded or unavailable, the augmentation service is considered not available and the pilot would rely on non-augmented GPS or other procedures. RAIM, by contrast, performs internal fault detection using redundancy but doesn’t broadcast an availability integrity status to the user. GBAS operates locally with ground-based corrections and integrity for a limited area, not the wide-area availability information WAAS provides.

Integrity information from a wide-area augmentation system is what lets a pilot know when GPS data can be trusted for use in operations. WAAS provides this kind of integrity data across a large region by processing GPS signals, computing corrections and integrity alerts, and broadcasting them through geostationary satellites. The receiver uses those integrity messages to decide whether the GPS service is available for a given operation (for example, supporting precision approaches like LPV). When WAAS integrity is good, the system indicates availability for the enhanced navigation service; if integrity is degraded or unavailable, the augmentation service is considered not available and the pilot would rely on non-augmented GPS or other procedures.

RAIM, by contrast, performs internal fault detection using redundancy but doesn’t broadcast an availability integrity status to the user. GBAS operates locally with ground-based corrections and integrity for a limited area, not the wide-area availability information WAAS provides.