ADS-B in Class C/D airspace

I understand that ADS-B will be required in class C and D airspace because a transponder is currently required in that airspace. But what about class C or D airspace around a towered airport when the tower is not manned? Does the airspace revert to class E when the tower is not in operation?

Can anyone cite a source that answers this question?

I think the answer is here...

From the FAA website. I don't see that ADS-B out is required in Class D. Did I miss it?

https://www.faa.gov/nextgen/equipadsb/research/airspace/

TX7A said:

From the FAA website. I don't see that ADS-B out is required in Class D. Did I miss it?

https://www.faa.gov/nextgen/equipadsb/research/airspace/

Click to expand...

OK, how about an airport in class C airspace when the tower is not in operation?

ADSB-out is not required in class D, unless it also falls into another required category - most commonly, within the mode C veil of a class B airport. As to your other question, What happens to class D when the tower closes? The answer is, it depends. At some airports the entire class D reverts to E. At others, the class D airspace below 1200’ AGL reverts to class G. The answer for any given class D airport can be found in the Chart Supplement, what used to be called the airport facility directory.

Ron, I vote yes, Class C 2020 ADS-B out regardless of primary airport tower status.

Link to 12 mb Ch 15 of pilot handbook of faa aero knowledge:

"Unless otherwise authorized by the ATC having jurisdiction
over the Class C airspace area, all aircraft within Class C
airspace must be equipped with the appropriate transponder
equipment meeting all applicable specifications found in 14
CFR part 91, section 91.215. Additionally, beginning January
1, 2020, aircraft operating in the Class C airspace described
in 14 CFR part 91, section 91.225, must have ADS-B
Out equipment installed, which meets the performance
requirements of 14 CFR part 91, section 91.227." chapter 15-9".

Pilots Handbook of Aero Knowledge 15-9 was first pub I found to reference.

https://www.google.com/url?sa=t&sou...Vaw317SwPpUaGHjTsVjIB3n72&cshid=1566170338208

Oh Jeez, Ron, just get the ADS-B and be done with it. It's not that expensive, aircraft wise. And the best thing is that us other aircraft will be able to "see" you.

An airport that is in (not under) class C is always within class C, regardless of an open or closed tower. Mode C or S, and, starting in January, ADSB-out, are required at all times. Class C never closes.
An airport that is under Class C has no requirement on transponder or ADSB. Same for an airport under class B if it is outside the mode C veil. All airspace within a mode C veil, OTOH, does have the mode C/S, and will have the adsb-out, requirements.

per far pt. 91 a transponder isn't actually required in class D, just 2 way communication. But to answer the original question, most of them revert to class E & G (altitude dependent) when the tower is closed. The reference is in the AIM.

I can't say that I've ever been in a class C that was less than 24/7, so I've never really considered it. Logic would say that it would have to follow the same convention since if the approach control facility is closed, there's nobody home to look at the transponder return anyway.

Having said that, logic sometimes doesn't play into regulation, so if somebody knows of a part time class C, I imagine the answer as to what kind of airspace it becomes in the wee hours would be listed in the notes section of the chart supplement. THat's where I'd start looking for it anyway.

hope that helps!