Two things are required for ADS-B Out capability: an approved position source—generally a Wide Area Augmentation System (WAAS)-approved GPS receiver—and an ADS-B transceiver. An existing, approved panel-mount GPS may qualify as your position source (among the most popular are the Garmin GNS 430W and GNS 530W).
However, if you’re one of the many aircraft owners who do not have an approved GPS WAAS navigator in your panel—you do not have to purchase one. Many ADS-B transceivers are available with optional, built-in WAAS GPS receivers.
Another solution is to install a standalone WAAS GPS receiver—kind of like blind encoders, which feed altitude information to some transponders, this GPS will provide position information only to your ADS-B transceiver. Products currently on the market include:
FreeFlight 1201 WAAS/GPS sensor, list price $2,995.
Trig TN70 WAAS GPS receiver with antenna, list price $3,325.
Some aircraft owners will not have a choice between the 978UAT and 1090ES ADS-B Out datalinks. For example, if you will fly in Class A airspace (above 18,000 feet) or in ADS-B airspace outside the United States, a 1090ES transceiver will be required. Most others can choose between UAT and 1090ES. AOPA’s online ADS-B selection tool will help you make the best choice.
The Universal Access Transceiver, or UAT, operates on 978 MHz. UATs generally are less expensive than a Mode S transponder, but be sure to consider installation expenses, including antennas. If you choose a UAT with the optional ADS-B In, you can receive FIS-B’s subscription-free weather information, as well as TIS-B traffic information. To date, the United States is the only country using UAT, so if you fly internationally, you’ll want the 1090ES datalink.
The 1090ES datalink employs a Mode S Extended Squitter transponder (ES for short, referring to the additional information appended to the Mode S transponder data) operating on 1090 MHz. In the United States, 1090ES is required for flight in Class A airspace (above FL180); it’s also the technology to choose if you fly internationally. While the 1090ES datalink provides traffic information, it does not receive weather data; if you’re required to broadcast your position using 1090ES and want subscription-free in-cockpit weather, you can choose a unit with dual datalinks (it will receive UAT as well as 1090ES), or you can use a portable ADS-B In receiver.
Remember that an altitude-encoding transponder, either Mode C or Mode S, still will be required equipment after the January 1, 2020, deadline for ADS-B Out.
To view the optional ADS-B In traffic and weather information, you will need an appropriate display. Glass panels excel at this. However, in many cases you can use an Apple iPad or a similar portable device to view this data in flight.
Although portable ADS-B In receivers are popular, they do not fulfill the FAA’s 2020 mandate for ADS-B Out. In addition, if they’re used in an aircraft that does not yet broadcast an ADS-B Out signal, traffic information displayed will be incomplete.