Since my J3 Cub was was not originally certificated with an engine-driven electrical system it's clear the 2020 ADS-B-Out mandate (U.S.) does not apply (except where specifically noted in FAR part 91).

If I install a wind-driven generator providing a limited electrical system for my J3, will I now be required to comply with the ADS-B Out 2020 regulations?

  • $\begingroup$ I suppose the answer may depend on "how" the generator is installed...whether it be by a 337, STC, or so forth. $\endgroup$
    – Steve V.
    Oct 10, 2018 at 19:47
  • $\begingroup$ @SteveV.- I think the pivotal language is "engine-driven electrical system" vs. "wind-driven electrical system." $\endgroup$
    – 757toga
    Oct 10, 2018 at 22:46

3 Answers 3


Part 91 is mostly clear on the subject:

§91.225 Automatic Dependent Surveillance-Broadcast (ADS-B) Out equipment and use.

(a) After January 1, 2020, and unless otherwise authorized by ATC, no person may operate an aircraft in Class A airspace unless the aircraft has equipment installed that—

More detail, that describes 1090 MHz ADS-B out equipment...

(b) After January 1, 2020, and unless otherwise authorized by ATC, no person may operate an aircraft below 18,000 feet MSL and in airspace described in paragraph (d) of this section unless the aircraft has equipment installed that—

More detail describing 1090 MHz or UAT ADS-B out...

(c) Operators with equipment installed with an approved deviation under §21.618 of this chapter also are in compliance with this section.

If you have this deviation, you're good.

(d) After January 1, 2020, and unless otherwise authorized by ATC, no person may operate an aircraft in the following airspace unless the aircraft has equipment installed that meets the requirements in paragraph (b) of this section:

(1) Class B and Class C airspace areas;

(2) Except as provided for in paragraph (e) of this section, within 30 nautical miles of an airport listed in appendix D, section 1 to this part from the surface upward to 10,000 feet MSL;

(3) Above the ceiling and within the lateral boundaries of a Class B or Class C airspace area designated for an airport upward to 10,000 feet MSL;

(4) Except as provided in paragraph (e) of this section, Class E airspace within the 48 contiguous states and the District of Columbia at and above 10,000 feet MSL, excluding the airspace at and below 2,500 feet above the surface; and

(5) Class E airspace at and above 3,000 feet MSL over the Gulf of Mexico from the coastline of the United States out to 12 nautical miles.

That's all airspace where ADS-B is required. A summary is shown in the following graphic:

ADS-B Out Airspace
Source: FAA

(e) The requirements of paragraph (b) of this section do not apply to any aircraft that was not originally certificated with an electrical system, or that has not subsequently been certified with such a system installed, including balloons and gliders. These aircraft may conduct operations without ADS-B Out in the airspace specified in paragraphs (d)(2) and (d)(4) of this section. Operations authorized by this section must be conducted—

That specifies which aircraft have an exception (with following detail on specifically what airspace they can operate in.) It has, however caused confusion as the wording is very similar to Part 91.215(b)(3) which specifies "an engine-driven electrical system" as opposed to "an electrical system".

Subsequently the FAA has published a Legal interpretation that clarifies the intent was not to create a more stringent requirement for ADS-B Out than for transponders; specifically from the interpretation:

As such, we have concluded that the same aircraft excluded from the transponder requirement are excluded from the ADS-B Out equipage. Accordingly, an aircraft that subsequently has been installed with batteries or an electric starter would not be required to equip for ADS-B Out.

So it appears that your J3 is exempt and would remain so unless you installed an engine-driven electrical system.

  • $\begingroup$ Great answer! That language was originally "transcribed" from the language about transponder requirements. I think a good summary of the above, and a non-cited answer to the OP would be: wherever it is currently legal to fly now without a transponder, then you can fly there in 2020 without ADS-B Out. The biggest exception is the Gulf of Mexico language, which is a "new" requirement for ADS-B that does not currently require a xpdr. You might want to include the helpful "visual aid" from the FAA that summarizes everything in your answer: faa.gov/nextgen/equipadsb/research/airspace $\endgroup$
    – Jimmy
    Nov 9, 2018 at 14:26
  • $\begingroup$ @Jimmy- I recently came upon a legal interpretation (and AOPA article referring to that interpretation) that essentially states that the ADS-B rule exempting aircraft not originally certificated with an "electrical system" is construed to mean "engine driven" electrical system. REF: interp and aopa $\endgroup$
    – 757toga
    Nov 9, 2018 at 15:09
  • $\begingroup$ @757toga Good catch. I'll update the answer. Also thanks to Jimmy for link to graphic. $\endgroup$
    – Gerry
    Nov 9, 2018 at 16:55

Mostly it affects airplanes with transponders operating in airspace that requires a transponder.


  • $\begingroup$ Airspace that requires a transponder is the real answer. $\endgroup$
    – Mike Brass
    Oct 10, 2018 at 2:16
  • $\begingroup$ This answer could be improved. This related answer notes the difference in where aircraft without engine-driven electrical systems and without ADS-B-out or transponders will be further prohibited by the 2020 ADS-B-out rules, compared to where they are currently prohibited by the transponder rules -- aviation.stackexchange.com/questions/65812/… $\endgroup$ Feb 24, 2020 at 16:54

This question appears to be asking if adding a wind-driven electrical system will change where you may fly your J3 Cub without ADS-B-out. No it will not.

This letter of interpretation from the FAA Office of the Chief Counsel clarifies that the references to aircraft "without electrical systems" in FAR 91.225 should be understood to instead read aircraft "without engine-driven electrical systems", following the phraseology used in FAR 91.215, and that the omission of the phrase "engine-driven" was simply a mistake.

If you are interested to know what additional airspace is now off-limits to your J3 Cub lacking engine-driven-electrical system, transponder, and ADS-B-out, that was open to you before the 2020 ADS-B-out regulations came into effect, see this related answer. In short, it is the airspace that lies directly above the ceiling of Class B and Class C airspace in the 48 contiguous states (including Washington D.C.) that is also above 10,000' MSL, as well as the Class E airspace at and above 3,000 feet MSL over the Gulf of Mexico from the coastline of the United States out to 12 nautical miles.

At least, that is clearly the original intent of the FAR. However, the FAR is rather poorly written, and arguably prone to mis-interpretation. This related question asks whether the FAA is interpreting FAR 91.225 in a more expansive way that would ban aircraft without engine-driven-electrical systems and without ADS-B-out from more airspace than noted above-- namely, from all airspace above 10,000' MSL over the contiguous 48 states and Washington D.C. (excluding airspace below 2500' AGL). It appears that the answer to that question is "no".


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.