The TT21 is a two-part low power Mode S transponder system with a compact control head that includes an integrated altitude encoder. The 130 watt power output qualifies this unit as a Class 2 transponder* which may be used on aircraft cruising slower than 175 knots and operating below 15,000 feet, IFR or VFR. Its compact size and efficiency makes the TT21 ideal for use via an auxiliary battery in gliders, balloons, or foot launched flight. It features simple operation and a clear and bright display with manual dimming, making it easy to read in all lighting conditions. The control head is splash proof — a perfect fit for use in open cockpit and seaplane operations.

*Customers in the U.S. should be aware that the FAA, Federal Aviation Regulations (FAR) 91.227, requires that a compliant ADS-B Out solution use a Class 1 transponder in U.S. controlled airspace. The TT22 is a Class 1 device and meets this requirement. The TT21 is a Class 2 device and does not meet this regulation. The FAA has stated that Class 1 transponders must be used to be 2020 compliant in U.S. controlled airspace. For this reason, it is recommended that the TT22 unit be used to meet the mandate’s requirements (see EDMO# 00772-00).

The TT21 complete kit (00710-00) includes the control head, hardware unit and tray, install kit, installation and user manuals, and an EASA Form 1.

• Fits in a standard 57 mm round instrument hole, requiring less panel space
• Integrated altitude encoder
• Certified for IFR/VFR flight
• Certified Class 2 transponder with 130 watts nominal output power
• Manual adjustment for backlight adjustment
• Compact and lightweight—weighing only 440g (0.8 lb)
• Low power consumption
• 1090ES ADS-B Out capable
• Free European Minor Change approvals
• EASA ETSO and FAA TSO Certification – includes TSO C166b, the latest ADS-B standard