May aerobatics be performed over a controlled airport without getting a waiver?

Question

CFR 14 Part 91.303 states:

Aerobatic flight.

No person may operate an aircraft in aerobatic flight--
(a) Over any congested area of a city, town, or settlement;
(b) Over an open air assembly of persons;
(c) Within the lateral boundaries of the surface areas of Class B, Class C, Class D, or Class E airspace designated for an airport;
(d) Within 4 nautical miles of the center line of any Federal airway;
(e) Below an altitude of 1,500 feet above the surface; or. (f) When flight visibility is less than 3 statute miles.
For the purposes of this section, aerobatic flight means an intentional maneuver involving an abrupt change in an aircraft's attitude, an abnormal attitude, or abnormal acceleration, not necessary for normal flight.

For the purposes of this question I want to focus on paragraph (c). Assuming we don't have any other specific permission (waiver), may aerobatics be performed above class B, C, D, or E surface airspace?

I know aerobatics may be performed under the outer rings of class B and C airspace.

There also doesn't appear to be anything preventing aerobatics above the outer rings of class B or C airspace.

So the question is focusing on the center core (the surface area) of class B and C as well as the typical cylinder of a class D airspace and whatever shape a class E surface area happens to be.

Paragraph (c) simply states "Within the lateral boundaries of the surface areas" but makes no mention of altitude (other than the 1500' AGL reference in paragraph (e)).

Obviously we are talking about surface areas that go to the ground so clearly you may not fly in or below these surface areas. But may you fly above them as long as you are 1500' AGL?

"within the lateral boundaries of" has no implied altitude restriction. That term, in English, implies surface to outer space. So it would seem that aerobatics may not be performed above a class B, C, D, or E surface area at any altitude.

But you may perform aerobatics above the outer rings of class B and C. So why restrict doing them over the surface area?

Is there an official answer? May I legally do aerobatics above class B, C, D, or E surface airspace?

I have searched and looked at many related topics but none address this specific question. Even the Hucker discussion leaves this unanswered (to me at least) which only clarifies being able to do aerobatics under (no mention of over) the outer rings of class B and C airspace.

Answer 1

Actually "within the lateral boundaries of the surface areas of any Class D, Class C, or Class B airpace" DOES imply that you are not permitted to do aerobatics over these areas without special permits from the FAA or if there is a designated aerobatic box at that airport and said pilot remains within that airspace. Even if you are not in the actual airspace itself, if you're above it, you're not allowed to fly acro over it.

Now, note the term "surface areas" could imply that you could fly aerobatics above or below Class C or Class B airspace SHELVES, that is a section of Class C or Class B airspace which does not touch the ground, provided you don't enter those areas and said airspace meets all the other requirements of FAR 91.303.

Answer 2

Consider the portion of class B, C, D, or E airspace that actually extends all the way to the ground. (In the case of Class E airspace, it is arguably ambiguous as to whether or not surface-level E3/E4 "extensions" that do not actually surround the airport in question qualify as "Class E airspace designated for an airport".¹)

The plain English meaning of "within the lateral boundaries of" does not imply any vertical limit of any kind.

Also, the FAA uses the term "surface area" to mean not just an area on a map, but rather a volume of airspace whose floor is actually in contact with the surface.³

So for all the portions of class B, C, D, or E airspace that actually extend all the way to the ground (again recognizing the Class E "extensions" fall into an ambiguous category), there is a cylinder (or more irregularly shaped column) of airspace going all the way to the top of the atmosphere and beyond -- or at least to the limit of the FAA's jurisdiction-- within which aerobatics may not be performed without a waiver, by virtue of FAR 91.303(c).

Aerobatics over or under or even within⁴ class B or C "shelf" airspace are fine, as long as you are not within the cylinder or column described above, extending upward indefinitely from controlled airspace that is actually in contact with the surface.

For more, see the 2006 Hucker interpretation, which reversed an earlier 1999 interpretation.⁵ The truth is, however, that the 2006 Hucker interpretation does not specifically address the issue of doing aerobatics above the ceiling of Class B, C, or D airspace. Instead we have to rely on the common-sense meaning of "within the lateral boundaries of...".

But you may perform aerobatics above the outer rings of class B and C. So why restrict doing them over the surface area?

That is a very good question. The ways of the FAA are unfathomable to mere mortals.

Footnotes:

1. I'll refrain from getting deeper into the controversial issue of surface-level Class E "extensions" (E3/E4 airspaces) here. To explore more, readers may wish to start with the related ASE answer "Does FAR 91.155c apply to class E surface extensions?", and then check out the additional links given at the end of that answer.

2. For a list of 11 other FARs whose wording contains the "within the lateral boundaries of" phrasing, see the related ASE question What indication has the FAA given that phrases like "surface area of Class E airspace designated for an airport" do or don't include E4 "extensions"?. Even if the reader has no interest in the "extension" issue, he or she may find the list of FARs to be of interest. Note that in some of these FARs, the "within the lateral boundaries of..." phrasing is only applied to surface-level Class E airspace, while in others of these FARs it is applied to surface-level controlled airspace in general. Two more FARs that use the "within the lateral boundaries of..." language, but apply it to the entirety of Class B and Class C airspace (which would include "shelves"), with no reference to surface area, are FAR 91.215(b)(4) and FAR 91.225(d)(3).

3. Re the FAA's use the term "surface area", sometimes capitalized as "Surface Area" -- see for example the language of the "Airspace Designations and Reporting Points" document quoted at the bottom of Page 1 of the FAA Memorandum reproduced in the ASE answer linked in footnote 1. See also the reference to ATC/FSS use of the phrase "surface area" in the text immediately above the map figure in that answer. Clearly in these cases we are talking about a volume of airspace whose floor is in contact with the ground, not just an area on the ground. However in reference to the present question, we'd come to the same conclusion even if the phrase were simply being used to describe an area on the ground, due the "within the lateral boundaries" phrasing. The location of the ceiling of the airspace called the "surface area of controlled airspace", or the question of whether "surface area" means a volume of airspace or an area on the ground, is actually irrelevant to the interpretation of FAR 91.303(c) and other FARs containing similar "within the lateral boundaries of" language. This point pertains especially to some of the answers given to the ASE question Which parts of class E airspace can an ultralight (part 103) fly in without prior ATC authorization? -- at least one answer really "misses the boat" on this point. (In fact, on at least one occasion, the FAA itself "missed the boat" on this point-- an October 1993 Final Rule pertaining to FAR 91.157(a) implied that the phrase "within the lateral boundaries of" somehow also implied a vertical limit, and therefore changed the language of FAR 91.157(a) to read "...within the airspace contained by the upward extension of the lateral boundaries of the controlled airspace designated to the surface...". It's odd that they didn't see a need to change the similar language in 91.303(a), as well as all the other FARs with similar language noted in footnote 2 of this answer. For details see this ASE answer to the ASE question "Which parts of class E airspace can an ultralight (part 103) fly in without prior ATC authorization?".)

4. Obviously, if you are within Class B or C airspace, you are subject to other constraints, namely instructions from ATC, which may prevent you from doing aerobatics without a waiver, but that has nothing to do with FAR 91.303(c). Note that the text of the Hucker ruling specifically states that the questioner asked "whether aerobatics may be performed within Class B airspace (with proper ATC clearance), and/or underneath the floors of Class B airspace." The ruling stated "aerobatics may be conducted in such outer areas (i.e. within the "shelves" that do not extend to the ground), provided that the requirements of 91.130 or 91.131 are met as applicable; and the requirements of 91.303 (a), (b), (d), (e) and (f) are met."

5. Apparently the text of this older 1999 decision is not currently available on the FAA's website. A search for Legal Interpretations using the key word "aerobatics" only yields results going back to the year 2000.