ICAO Standards and Recommended Practices (SARPs) for GBAS are published within the Global Navigation Satellite System (GNSS) provisions and define the baseline global requirements for:

• system definition and terminology

• GBAS service levels (GAST)

• functional and performance requirements

• integrity, continuity and availability objectives

• ground subsystem functions

• airborne subsystem functions

• interoperability and message formats (high-level)

SARPs form the international foundation that ensures a GBAS installation in one State is usable by properly equipped aircraft certified elsewhere, enabling standardized GLS approach publication worldwide.

Detailed Minimum Operational Performance Standards (MOPS) are issued collaboratively by RTCA (US) and EUROCAE (Europe) and provide the technical performance requirements for both airborne and ground GBAS elements.

Major elements covered:

• system architecture assumptions

• fault detection / fault exclusion (FDE)

• ionospheric threat models and error bounding

• monitoring and protection level generation

• continuity requirements and failure response

• message structures and data content

• certification test procedures

MOPS serve as the primary technical basis for equipment qualification and type design approval, and are referenced by both aviation authorities and manufacturers during certification.

While SARPs and MOPS define standardized performance and design criteria, national civil aviation authorities (for example FAA, EASA and other ANSPs/CAAs) evaluate compliance and issue operational approvals for:

• GBAS ground installations at specific airports

• published GLS procedures

• airborne equipment approvals

• operator/airline approvals (including training and operations manuals)

• authorized minima (CAT I through CAT III)

Authorities may also publish additional guidance material, advisory circulars or certification policies addressing:

• site-specific analysis

• meteorological conditions

• RF environment

• operational contingency procedures

• transition to/from ILS

For CAT II/III, national evaluations typically include enhanced continuity and failure-recovery demonstrations and more stringent testing under representative operational conditions.

Beyond system certification, GBAS requires standard aviation documentation, including:

• published GLS approach procedures in national AIPs

• operator manuals and training material

• MEL/CDL considerations for GLS

• ATC procedures and phraseology

• NOTAM processes for GBAS availability

These items ensure that the certified capability is operationally integrated and transparently communicated to all users.