This Interface Control Document (ICD) defines the Signal-in-Space for the Global Navigation Satellite System (GNSS) based Local Area Augmentation System (LAAS). The LAAS has global application as a Ground-Based Augmentation System (GBAS) to the GNSS.

The content of this ICD that supports Category I Precision Approach and the differential positioning service is intended to be consistent with standards developed by the International Civil Aviation Organization (ICAO) and The European Organization for Civil Aviation Equipment (EUROCAE).

Within this document, the terms "LAAS" and "GBAS" are not synonymous. "LAAS" refers to the system being proposed by the RTCA to meet the operational objectives for the United States (US) National Air Space (NAS) as documented in RTCA/DO-245(). This system may also be suitable for implementation in other areas. "GBAS" refers to any system compliant with the ICAO standards (through and including Amendment 91 to ICAO Annex 10).

LAAS may implement the GBAS approach service and/or the positioning service based on GPS and, optionally, visible SBAS/WAAS geostationary satellites. The GBAS approach service has an optional broadcast of ephemeris error bound parameters. LAAS requires the broadcast of the ephemeris bound parameters. LAAS requires the broadcasting of additional information when supporting GBAS Approach Service Type (GAST) D (see Section 1.3.2).