I am a C-5 pilot and we are finishing an avionics upgrade that makes us GATM compliant. We have ADS-C. I'm attempting to figure out if we have ADS-B and I'm not sure because our flight manual is unclear.
I'm trying to determine if we have ADS-B. And if we do, what parameters in the flight computer would be required to be loaded in order to trigger it properly providing a position. It's possible that some of the required items to be loaded are only loaded during oceanic crossings. But again, this is all speculation since the manual only refers to ADS in general and does not break down how each of the types of ADS is utilized.
From what I have seen of various USAF transports coming over the UK (C-17s, C-5s, Hercs, KC-10s, KC-135s) none of them ever transmit ADS-B. Presumably the C-17s have all the gadgets etc to be GATM compliant, I think they just switch off ADS-B, after all its not required I don't think. USN E-6s seem to always have it on, and sometimes you'll get a USAF or USN Gulfstream that also has it on.
Even more confusing, the F-15 eagles at Lakenheath fly with 'tactical' hex codes, meaning they are changed around very frequently making it impossible to ID an a/c based on its hex code.
ADS-B is going to be a GATM requirement from what I understand. I flew legacy C-130s and we didn't have any of those capabilities. I'm told the J model requires some additional equipment to be so. I'm not sure what the C-17 has as I've never flown it but from what I've read they are not FANS/1A or CPDLC and don't have any ADS.
C-5s are getting a transponder upgrade and I wouldn't be surprised if it includes ADS-B but I haven't actually read anything to confirm that.