Shop Talk

August 20, 2009

Wish you had a better understanding of the regulations when talking to your mechanic or the avionics shop? Aircraft Electronics Association Vice President of Government/Industry Affairs Ric Peri answers your frequently asked questions.

Shop Talk: GNSS equipment

Question: What is GNSS and where can I find guidance on the installation of these systems?

Answer: Global Navigation Satellite System (GNSS) is a generic term for satellite-based navigation, including GPS, SBAS, GBAS, the Russian Global Navigation Satellite System (GLONASS), and any other satellite navigation system. GNSS sensors include those incorporating Wide Area Augmentation System (WAAS), Local Area Augmentation System (LAAS), and GLONASS.

GPS is a U.S. satellite-based radio navigation system that provides a precise positioning service anywhere in the world. The service provided by GPS for civil use is defined in the GPS Standard Positioning System Signal Specification.

Satellite-Based Augmentation System (SBAS) is a wide coverage augmentation system in which the user receives augmentation information from a satellite-based transmitter.

Ground-Based Augmentation System (GBAS) is an augmentation system in which the user receives augmentation information directly from a ground-based transmitter.

GLONASS is a Russian satellite-based radio navigation system, which provides a positioning service anywhere in the world

Advisory circular (AC) 20-138A provides guidance material for the airworthiness approval of GNSS equipment. The AC also includes information of the installation of GNSS equipment in “in-service” aircraft.