According to Scotland-based Trig Avionics, “A UAT solution will often be more expensive” than a 1090ES-based solution because the latter uses relatively common Mode S transponders: The 978 UAT standard employs a separate transceiver—and U.S. operators complying with ADS-B OUT via 978 UAT still will need a Mode A/C transponder in the foreseeable future, until the FAA says otherwise.
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For many general aviation operators—e.g., those operating below FL180—an ideal solution may be an “all-in-one” box incorporating WAAS-enhanced GPS and a 978 UAT transceiver, plus a means by which the ADS-B IN weather and traffic information can be displayed. Examples pictured here include FreeFlight Systems RANGR 978 product line (top) and Garmin International’s GDL 88.
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The market is operators who either don’t have a certified GPS navigator at all or the one they have isn’t WAAS-enhanced. Rather than yank out a perfectly good GPS or bite the financial bullet leading to a complete panel makeover, they can easily get by with a remote-mounted WAAS GPS receiver.
So far, the presumption is that any light GA operator needing to install ADS-B OUT also will want ADS-B IN to be part of the bargain, and that means using 978 UAT technology. Maybe, but there’s nothing saying a 1090ES
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transponder like BendixKing’s KT 74 can’t be the basis of an approved ADS-B OUT solution for a piston single operator for whom ADS-B IN has no value, and who’s going nowhere near FL180. Getting ADS-B OUT approved aboard an in-service aircraft can be as simple as adding a compatible Mode S transponder like Trig’s TT31 (bottom) and a nav data source like FreeFlight’s 1201 (not pictured).