Is ADS-B required for flight under class B airspace but outside the Mode C veil?

Question

In the U.S., can a non-ADS-B equipped aircraft legally fly under class-B airspace extensions that are outside of the 30nm Mode-C Veil circle?

Answer 1

You may fly without ADSB under the Class B or Class C shelf provided you remain outside of any Mode C veil.

§91.225 tells you where you cannot fly. It says you cannot fly within the lateral boundaries of the Class B or C airspace or above the airspace. It does not say anything about under the shelf.

Here is an example of one such area:

skyvector.com

You can fly under 2,700' below the Ontario Class C and in the small slice of Class B you can fly up to 8,000' if you stay away from the Class C.

Paul Bertorelli has a good explanation on YouTube. (Updated link.)

(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.

14 CFR § 91.225

Answer 2

The question appears to be asking "Can a non-ADS-B-equipped aircraft legally fly under Class-B airspace shelves that are outside any 30nm Mode-C veil?"

Yes it can.

See FAR 91.225. The only clause in FAR 91.225 that at first glance might suggest otherwise, is 91.225(d)(3), which states "(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: ... (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;"

The most logical interpretation of this clause is that it only pertains to airspace that is simultaneously above the ceiling and "within the lateral boundaries" of a Class B or Class C airspace area. In other words, the airspace being described is all the airspace that lies directly above the ceiling of a Class B or Class C airspace area, up to 10,000' MSL. (And note that flying directly above the ceiling of Class B or Class C airspace above 10,000' MSL without ADS-B-out is prohibited by the combined action of 91.225(d)(4) and 91.225(e)(2).) Therefore the clause in question does not restrict flying directly below the floor of a shelf of a Class B or Class C airspace area.

It would be illogical to interpret this clause to be inclusive of all airspace below 10,000' MSL that is directly "above the ceiling" or "within the lateral boundaries" of a Class B or Class C airspace area, because in that case the "above the ceiling" phrase would be redundant and the clause would have exactly the same meaning if the phrase were simply deleted. All airspace that is located directly above the ceiling of a Class B or Class C airspace area also lies "within the lateral boundaries" of that Class B or Class C airspace area.

Yet another interpretation of this clause might take the "above the ceiling" phrase to also include airspace that is higher than the ceiling of a nearby Class B or Class C airspace area, but displaced laterally rather than actually overlying that Class B or Class C airspace area. Now if the clause is interpreted to include all the airspace that is "above the ceiling" of a Class B or Class C airspace or "within the lateral boundaries" of a Class B or Class C airspace area, flight beneath Class B or Class C shelves would be prohibited. However, this interpretation is completely unfeasible because there would be no way to know how far from the edge of the Class B or Class C airspace the prohibition against flying "above the ceiling" should be considered to apply.

Note that if the aircraft in question has no engine-driven electrical system, then the 30-nm Mode C veil is no longer an issue. In this case the answer given above would also apply to the portions of Class B or Class C shelves that lie within the 30-nm Mode C veil-- such an aircraft would be free to fly under those Class B or Class C shelves.

One final note-- if the aircraft in question has no engine-driven electrical system and no ADS-B-out, then operations conducted within the lateral boundaries of Class B or Class C airspace must be conducted below 10,000' MSL, due to FAR 91.225(e)(2), as explained in more detail in this related answer. There is at least one instance (KSLC) where the floor of a Class B or Class C shelf is above 10,000' MSL, and thus an airplane with no engine-driven electrical system and no ADS-B-out could not legally fly all the way up to the floor of that shelf. An aircraft with no ADS-B-out that does have an engine-driven electrical system must stay below 10,000 MSL in all airspace over the contiguous 48 states that is not below 2,500 AGL due to FAR 91.225(d)(4), and so it too could not legally fly all the way up to the floor of a Class B or Class C shelf above 10,000' MSL, at least if that shelf had a floor higher than 2500' AGL and was located within airspace over the lower 48 states, even if that shelf were outside of any 30-nm Mode C veil, which the above-mentioned shelf at KSLC is not.

Here is an A.S.E. answer that addresses a question that is somewhat similar what to what is being asked here, but specifically focussed on aircraft lacking an engine-driven electrical system: What additional airspace will be off-limits to an a/c w/ no elect. system or xponder under 91.225 (ADS-B) compared to under 91.215?