GNSS alone does not always provide the integrity required for safety‑critical precision approaches and autoland operations. GBAS supplies real‑time integrity information and protection levels so pilots can make trustworthy go/no‑go decisions.

Unaided GNSS is vulnerable to spatially correlated errors, multipath and signal distortions. GBAS broadcasts differential corrections that remove most of these common errors between the ground site and the aircraft.

Traditional Instrument Landing Systems (ILS) installations require a separate localiser/glideslope and frequency for each runway end. GBAS can replace multiple ILS units with a single ground facility, reducing infrastructure, maintenance and VHF frequency use.

ILS supports mainly straight‑in approaches. GBAS enables curved, segmented and continuous‑descent approaches, allowing optimized trajectories that avoid obstacles and noise‑sensitive areas.

Non‑optimized approaches often produce holdings or longer flight paths. GBAS‑enabled procedures (continuous descent and tailored paths) lower fuel burn, gas emissions, and community noise exposure.

ILS requires protected critical areas that constrain taxiing and ground movements. GBAS siting typically reduces those protected areas, easing surface operations and airport logistics.

GNSS can be affected by ionospheric gradients, ionospheric scintillations, satellite faults and interference. GBAS mitigates many of these threats through multi‑receiver monitoring, Fault Detection and Exclusion (FDE), and, when implemented, multi‑frequency/multi‑constellation processing.

By providing ground monitoring, redundancy and corrective broadcasts, GBAS improves the availability and operational resilience of precision approach services compared with unaided GNSS.