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 ADS-B position source, including:
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.