Does ADS-B out require a transponder?
For aircraft operating below 18,000 feet and within the United States ADS-B rule airspace, you must be equipped with either a Mode-S transponder-based ADS-B transmitter or with UAT equipment. ADS-B only became mandatory in 2020. In most aircraft, you cannot turn off ADS-B without also turning off the transponder. ATC radar can track aircraft (primary radar) even if they do not have a transponder, but other aircraft won’t see it on their TCAS/ACAS.
Does ADS-B require a transponder?
For aircraft operating below 18,000 feet and within the United States ADS-B rule airspace, you must be equipped with either a Mode-S transponder-based ADS-B transmitter or with UAT equipment. For aircraft operating at or above FL180 (18,000 feet), you must be equipped with a Mode S-transponder-based ADS-B transmitter. For aircraft operating below 18,000 feet and within U. S. Mode S transponder with Extended Squitter or a Universal Access Transceiver (UAT).
Is ADS-B out a transponder?
If your aircraft has ADS-B Out capability, it’s built on Mode S transponder technology. As a student pilot, you might fly aircraft with either Mode C or Mode S transponders. Mode C/S transponders transmit on the 1090 MHz frequency, just like ADS-B. However, the main difference lies in the amount of information transmitted. The message from a Mode C/S transponder is much less detailed than that of ADS-B.