Mode S? Registration encoded into mode C?

Since AFAIK Mode S is not a requirement (not used?) in North America, I guess it’s not surprising the tail number programming was over-looked…and not surprising ATC did not comment…

Pilot_DAR wrote:

Am I pushing my luck? Will a radar/information controller hold me up for it?

Dubrovnik tonight, Split tomorrow, will report. Thanks for the help!

You’ll probably be warned to correct this by Croatian ATC. They usually warn airliners if they mistype flight identifier.

AnthonyQ wrote:

Since AFAIK Mode S is not a requirement (not used?) in North America, I guess it’s not surprising the tail number programming was over-looked…and not surprising ATC did not comment…

Mode S is essentially required for aircraft for hire and Turbojet in the US. TCAS II depends on mode S for its operation. Mode S configuration is part of the installation manual instructions and the 91.413 transponder check that is required for operation in the US NAS.

From part 43, Appendix F:

Note: The tests in (e) through (j) apply only to Mode S transponders.
(e) Mode S Diversity Transmission Channel Isolation: For any class of Mode S transponder that incorporates diversity operation, verify that the RF peak output power transmitted from the selected antenna exceeds the power transmitted from the nonselected antenna by at least 20 db.
(f) Mode S Address: Interrogate the Mode S transponder and verify that it replies only to its assigned address. Use the correct address and at least two incorrect addresses. The interrogations should be made at a nominal rate of 50 interrogations per second.
(g) Mode S Formats: Interrogate the Mode S transponder with uplink formats (UF) for which it is equipped and verify that the replies are made in the correct format. Use the surveillance formats UF=4 and 5. Verify that the altitude reported in the replies to UF=4 are the same as that reported in a valid ATCRBS Mode C reply. Verify that the identity reported in the replies to UF=5 are the same as that reported in a valid ATCRBS Mode 3/A reply. If the transponder is so equipped, use the communication formats UF=20, 21, and 24.
(h) Mode S All-Call Interrogations: Interrogate the Mode S transponder with the Mode S-only all-call format UF=11, and the ATCRBS/Mode S all-call formats (1.6 microsecond P4 pulse) and verify that the correct address and capability are reported in the replies (downlink format DF=11).
(i) ATCRBS-Only All-Call Interrogations: Interrogate the Mode S transponder with the ATCRBS-only all-call interrogation (0.8 microsecond P4 pulse) and verify that no reply is generated.
(j) Squitter: Verify that the Mode S transponder generates a correct squitter approximately once per second.

AnthonyQ wrote:

Since AFAIK Mode S is not a requirement (not used?) in North America, I guess it’s not surprising the tail number programming was over-looked…and not surprising ATC did not comment…

I believe I have flown in one US-registered light piston powered aircraft with Mode S, ever. Mode C only is the norm for light aircraft unless its a new production plane or you’re flying over 18,000 ft. Mode S below 18,000 feet is not required in any kind of airspace.

Silvair,

More and more aircraft in the US are installing or have installed mode S. The original push was for the Traffic system that mode S has in the US. Many thousands of piston aircraft had the GTX330 installed as a result of this feature, including mine. Later on, with the ADS-B mandate, about 2/3 of the ADS-B Out installations are based on mode S, for example the GTX330ES, GTX345, Trig TT31, KT74 and others. About 10% of the fleet is now equipped with ADS-B Out using mode S.

There is currently no mandate for mode S at any altitude, it is purely optional for GA users that are not involved in commercial operations. After 2020, mode S based ADS-B Out will be required above 18000 MSL, but we still have 3 and a half years until that kicks in.

Pilot_DAR wrote:

I did look for the “transponder page” in the GTN750, and could not find it.

Just hit the squawk code to bring up the transponder page. If enabled, you could change the Flight ID there. It is possible that the installer has choosen too hide this from the menu. Then it should be done in the configuration menu.

Had another G1000 in the other day, where ICAO adress is programmed, but where FID was set as “N” without any suffix.
On this aircraft it seems a flight ID configuration issue as well, not an aircraft adress issue.