ADS-B transponder regulatory question

[Dugaru]

For the next few days, my ADS-B out transponder (a Garmin GTX330ES) will be without its source of GPS info. Because I have too much time on my hands, and want to do some flying in the meantime, this generated several questions.

1. Will the transponder automatically cease broadcasting ADS-B out -- or will it be sending out incomplete data that runs the risk of annoying ATC, generating form letters, etc.?

2. If the latter, can it be temporarily configured to operate as an "old school" transponder? Obviously I would need to avoid areas where ADS-B out is required.

3. Under the often-ignored provisions of 14 CFR 91.215(c), all aircraft " equipped with an operable ATC transponder maintained in accordance with § 91.413" are REQUIRED to have that transponder turned ON in ALL "controlled airspace" (not just in airspace requiring transponders). On the East Coast of the US, basically everything is controlled airspace. If my ADS-B out transponder lacks GPS data, is it "inoperable" such that I can just turn the thing off (obviously avoiding transponder-required airspace)? Or is it still "operable" such that I have to come up with a way to leave it on? The reg suggests to me that I can't just declare something inoperable if it actually "works."

 

[AZSteve053]

So - I could speculate, but that's not my character. Ops will depend on how Transponder decides if on ground or in-air (sometimes a Pitot-static input, mostly derived from GPS velocity). I strongly suggest you contact Garmin support for a real answer.

 

[Walt]

If you go into the setup menu of the 330 you can turn the GPS source to 'none' and operate it as a typical mode S transponder.
(no ADS-B functionality)

 

[moosepileit]

Read cfr 91.225 at para f.

Federal Register :: Request Access

I'd use the ADAPT website or sit.

Loading…

www.faa.gov

See ADAPT Question #2 and #4. It does not appear intended for multiple or leisure flights.

Automatic Dependent Surveillance - Broadcast (ADS-B) Service Availability Prediction Tool (SAPT) — Flight Information Entry Form

ADSB

sapt.faa.gov

Don't know what a Mode S sans ADSB-Out GPS source looks like to ATC. It would generate a bad PAPR, though, no?

Edit- I see Walt's posted, turning it into Mode S means with the tail # ID- PAPR would generate as bad?

 

[AZSteve053]

I would wonder if Altitude Info is still available - if not then mode-C non functional

 

[jspey]

Is this like saying if the encoder hooked to my old KT76 transponder is down for maintenance, can I placard "mode C inop", and run it in mode A only?

 

[Walt]

I would wonder if Altitude Info is still available - if not then mode-C non functional

Mode C/S uses an altitude encoder, not GPS altitude.

 

[Walt]

Is this like saying if the encoder hooked to my old KT76 transponder is down for maintenance, can I placard "mode C inop", and run it in mode A only?

No, if you're in airspace that requires a transponder then Mode C is required, or you will need special authorization to fly without.

 

[Dugaru]

If you go into the setup menu of the 330 you can turn the GPS source to 'none' and operate it as a typical mode S transponder.
(no ADS-B functionality)

Exactly what I needed to know -- thanks very much!

 

[Longez]

Don't forget that the GTX 330ES is an ADS-B Out transponder because it has the Extended Squitter (ES) option (and V7.01 or later software).

As explained in the installation manual, if you wish to disable ADS-B Out (and ES), go to the ADS-B TX page in configuration mode and set this parameter to DISABLE. This should make it perform like a Mode S transponder without ADS-B Out (ES).

 

[Walt]

Don't forget that the GTX 330ES is an ADS-B Out transponder because it has the Extended Squitter (ES) option (and V7.01 or later software).

As explained in the installation manual, if you wish to disable ADS-B Out (and ES), go to the ADS-B TX page in configuration mode and set this parameter to DISABLE. This should make it perform like a Mode S transponder without ADS-B Out (ES).

Thanks Steve for the extra details, been a LONG time since I was actually in the menu of a 330.

 

[BobTurner]

No, if you're in airspace that requires a transponder then Mode C is required, or you will need special authorization to fly without.

I think he was asking about controlled airspace below 10,000’, and not in B or C nor inside a mode C veil. Is his transponder ‘operable’ (but mode A only) and hence should be on in this airspace? Or is his transponder known to be faulty, and should be turned off?

 

[Dugaru]

I think he was asking about controlled airspace below 10,000’, and not in B or C nor inside a mode C veil. Is his transponder ‘operable’ (but mode A only) and hence should be on in this airspace? Or is his transponder known to be faulty, and should be turned off?

My theory (and it’s only that) is that it’s either inoperable, and thus can be legally turned off, OR that 14 CFR 91.215(c) doesn’t apply regardless of the operability issue - because once his mode C is gone, he’s no longer an aircraft "equipped with an operable ATC transponder maintained in accordance with § 91.413"

Perhaps that language also makes it legal to turn off a transponder that’s overdue for its biennial certification. Because you certainly aren’t supposed to fly around with one of those turned on.

But the FAA may well have some letter putting the lie to these theories, so nobody should rely on them.

 

[Dugaru]

Don't forget that the GTX 330ES is an ADS-B Out transponder because it has the Extended Squitter (ES) option (and V7.01 or later software).

As explained in the installation manual, if you wish to disable ADS-B Out (and ES), go to the ADS-B TX page in configuration mode and set this parameter to DISABLE. This should make it perform like a Mode S transponder without ADS-B Out (ES).

Having now read the pilot's guide ("when all else fails..."), it looks like the transponder will turn ADS-B broadcasts off (a) when ADS-B TX is disabled in the configuration mode (as you describe) OR (b) if "ADS-B is configured ON but [the transponder] cannot transmit the position of the aircraft." That's a nice feature, apparently tailor made to my situation.