The GDL90 is a TSO C154 remote-mount unit, certified to support a broad array of Automatic Dependent Surveillance-Broadcast (ADS-B) broadband services. It is designed to interface with the MX20 multi-function display and includes a TSO-C145a WAAS GPS sensor that offers outstanding position accuracy and integrity.

The GDL90 uses ADS-B technology — a new technology that allows pilots in the cockpit and air traffic controllers on the ground to "see" aircraft traffic with much more precision than has ever been possible before. ADS-B can make flying safer and can provide more efficient use of our airspace. It is the enabling technology behind the FAA's vision for an air traffic management concept known as "Free Flight."

The Garmin GDL90 is designed to transmit, receive and decode ADS-B messages via a digital datalink. It broadcasts your aircraft's position, velocity, projected track, altitude, and flight identification to other equipped aircraft in your vicinity, as well as to ground-based transceivers maintained by the FAA.

The GDL90 relies on the infrastructure that is part of the FAA's Safe Flight 21 program. This program is currently under development with implementation of the ground-based portion of the ADS-B network taking place along the East Coast and in Arizona. Additional installations of ADS-B ground stations are planned for Alaska and the Gulf of Mexico, with the rest of the U.S. to follow.

The ground stations can track aircraft movement and will eventually be used to broadcast traffic and weather services. Pilots equipped with the GDL90 and operating within the ground station coverage area will receive TIS-B traffic, FIS-B weather, and TRF services free of charge. There are no monthly fees or usage charges.