With the requirement for all airplanes flying in regulated airspace to equip with ADS-B on the books for 2020, Garmin has introduced the GTX 23 transponder as a lower-cost option for experimental aircraft or LSA to meet the rules. The new remote-mounted transponder will operate with Garmin’s G3X flat glass display system found on experimental aircraft and used on LSA such as Cessna Skycatchers.
The GTX 23 employs Mode S “extended squitter” (ES) to broadcast required ADS-B data. Standard Mode C transponders broadcast only a four-digit code and pressure altitude data. But when the GTX 23 is linked to a position source of sufficient accuracy—such as a WAAS GPS—the ES function automatically broadcasts aircraft position, velocity, altitude, vertical velocity and identification, plus other specific information.
The NextGen (next generation) air traffic control system will use the data broadcast by all airplanes in the system in place of radar to achieve more accurate traffic surveillance.
The transponder boasts 250 watts of power for a sticker price of $2,199, according to Garmin, about one-third of the cost of other so-called 1090 ES transponders designed for certificated airplanes.
Garmin also announced a lower price for the G3X flat glass system starting at under $6,000. The heart of the G3X is a flat glass primary flight display (PFD) using solid-state attitude and digital air data sensors and an integral GPS sensor. The basic G3X system can be expanded to include two or more multifunction displays and also display subscription-based XM Satellite weather, Garmin SafeTaxi charts, moving maps, and Garmin FliteCharts.
The G3X PFD includes synthetic vision, a computer-generated image of terrain and obstructions to enhance situational awareness in all conditions. The G3X system can also be linked to a variety of VHF comm transceivers and GPS navigators from Garmin and can, with the necessary sensors installed, serve as the engine monitoring system.
It’s impossible to know what GPS sensors will become available in the future to provide the necessary data to satisfy the ADS-B requirements, but the “ES” capability of the GTX 23 transponder does qualify for the rules the FAA has already published.