Steve- I didn’t realize Mode C had an Alt Encoder and transmitted altitude…
Good Info, Thanks [H]
BTW, What exactly is a UAT? [^o)]
If you have a Garmin 327 it is Mode C (the majority of the fleet)
If you have a Garmin 330 it is Mode S
UAT (Universal Access Transceiver? [not 100% sure of the acronym]) is one of two ways to become compliant with the 2020 ADS-B out mandate. Only applies to aircraft under 18,000 and in the US. So if you fly above 18,000 or (possible?) internationally, this option is not for you. But it is typically cheaper than the Mode S-ES option for ADS-B compliance.
Hi Steve,
Sheesh, this is complicated. I know we have a mode S transponder (its code is even on the FAA’s registry website, but I don’t know about the the “ES”. Guess we’ll have it checked it out at the next annual inspection.
Thanks much for your insightful answer,
Andrew D.
i bet you have a mode S since you have a 2012, but the code on the FAA registry doesn’t mean it is mode S. My aircraft shows the same but, I have a mode C Garmin 327.
The “Mode S” you see on your FAA registration page is one that was assigned by the FAA to your aircraft FOR USE when you do install a Mode S/ADS-B. Just waiting for you to use…
Mode A is the “squawk code” you enter in on the XPDR. Mode C is the altitude reporting info from the encoder.
The Garmin GTX-327 XPDR is a Mode A/C XPDR.
Mode S stands for “selective” meaning that it can be interrogated selectively based on the 24-bit ICAO address. It also provides the Mode A/C information when interrogated in those modes by the ATCRBS. The 24-bit ICAO address is already assigned to EVERY aircraft registration. When the Mode S XPDR is installed, the 24-bit ICAO address needs to be programmed into (often hard strapped to the connector) the Mode S XPDR. Every 24-bit ICAO address is unique and is essentially an electronic fingerprint for the aircraft.
The Garmin GTX-330 is a Mode S XPDR.
All XPDRs (Mode A, C, and S) transmit at 1090MHz.
ADS-B (excluding the UAT - which is only an option in the US) requires a Mode S XPDR that is capable os Extended Squirter (aka 1090ES) for the additional information required to me transmitted for ADS-B (like WAAS GPS position).
In simplistic terms, to comply with the ADS-B 2020 mandate (excluding the UAT as an option) you need a Mode S Extended Squirter XPDR (like the GTX-330ES) and a TSO’d and ADS-B compliant WAAS GPS source.
If you only operate in the US (and don’t plan to go anywhere outside of the US like Canada) then a UAT might be an option…and there are many options to consider with those. Like this one: http://www.flyingmag.com/avionics-gear/instrumentaccessories/freeflight-unveils-sub-2000-ads-b-out-unit