## Short Answer ## > within the lateral boundaries of the surface area of Class E airspace designated for an airport This refers to the horizontal dimensions of Class E airspace that contacts the surface of the earth without any reference to vertical dimensions or ceiling. ___ ##Long Answer## You ask for definitive and official clarification on the following two portions of [§103.17][1]: > within the lateral boundaries of and > the surface area of Class E airspace designated for an airport Here is [§103.17][1] in full for context: > **Operations in certain airspace.** >No person may operate an > ultralight vehicle within Class A, Class B, Class C, or Class D > airspace or within the lateral boundaries of the surface area of Class > E airspace designated for an airport unless that person has prior > authorization from the ATC facility having jurisdiction over that > airspace. I will address these two clauses separately based on the official legal interpretations, then address your six case questions based on the definitions established. Throughout this answer I will also assume that no "prior authorization" has been obtained from ATC that would give exception to the above regulation. ___ "within the lateral boundaries of..." ------------------------------------- The terminology, "the lateral boundaries" refers to the horizontal limits of an area in question; the terminology does not refer to any vertical limits. Because "lateral" defines only horizontal area—not vertical—the terminology "within the lateral boundaries" means within the horizontal area defined, without respect to any vertical bounds, unless otherwise specified. Where a regulation needs to define vertical limits, additional terminology is used, such as "below [altitude]" or "above the ceiling". Compare the ultralight rule of §103.17 with wording of the following regulations respectively governing unmanned free balloons and transponder use—both of which define the horizontal limits of the airspace in question by the same terminology "within the lateral boundaries of the surface area[s]": > [§101.33][2] (a) Unless otherwise authorized by ATC, **below 2,000 feet above the surface** within the lateral boundaries of the surface areas of Class B, Class C, Class D, or Class E airspace designated for an airport; <p> >[§91.215][3] (4) All aircraft in all airspace **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; and ___ "...the surface area of Class E airspace..." ------------------------------------------------------------------- <sup>*Note: Credit goes to [Pondlife][4] for [identifying][5] the legal interpretation—Hucker (2006)—that addresses this issue.*</sup> The FAA has defined this terminology very clearly and without ambiguity. The following definition of "surface area" is provided in the [Pilot Controller Glossary][6]: > SURFACE AREA− The airspace contained by the lateral boundary of the > Class B, C, D, or E airspace designated for an airport that begins at > the surface and extends upward. Tthe FAA has issued a letter of legal interpretation—[Hucker (2006)][7]—that definitively addresses this: > The term “surface areas” refers only to those components of airspace that come in contact with the surface of the earth. Moreover, Hucker (2006) addresses the regulations of [§91.303][8] pertaining to aerobatic flight (which contains some of the same language as §103.17): > **§91.303** > (c) Within the lateral boundaries of the surface areas of Class B, > Class C, Class D, or Class E airspace designated for an airport; In addressing this regulation, Hucker (2006) makes clear that the above defines lateral areas without any vertical limitation. ___ "...designated for an airport" ------------------------------ I would argue that this phraseology is superfluous and that the FAA also regards it as such. I know of no Class B, C, D, or Class E airspace that extends to the surface that is *not* designated for an airport. I would be happy to be shown wrong, however. As I said, I believe the FAA also views this language as superfluous: In the FAA's ATC order [JO 7110.65W][9] the rules for SVFR are addressed in reference to the applicable airspaces, but without differentiation as to whether or not such airspaces are designated for an airport: > **7-5-1** > 2. Only within the lateral boundaries of Class B, Class C, Class D, or Class E surface areas, below 10,000 feet MSL. Additionally, in a memorandum of legal interpretation, [Duncan (2015)][10], the airspeed rules of §91.117 for Class B airspace are addressed, also without differentiation as to whether or not the Class B airspace is designated for an airport. ---------- Given the above, I would answer your six questions as follows: > **Question 1:** >What exactly is *the surface area of Class E airspace designated for an airport*? Is it any dashed magenta area on a sectional or is it something more specific or different? Yes, the *surface area of Class E airspace* is the component of Class E airspace that contacts the surface of the earth and extends upward. >**Question 2:** >And does the *within the lateral boundaries of* part mean there is no ceiling (meaning an ultralight can't overfly these areas at any altitude) or something else? Yes, in the context of §103.17 where no vertical dimensions are specified, *within the lateral boundaries* means inside the horizontal area with no vertical limitation or ceiling. >**Question 3:** >Can an ultralight fly within the dashed magenta circle? Is this an example of a "surface area of Class E airspace designated for an airport"? No, without prior authorization, no person may operate an ultralight vehicle within the lateral boundaries of the surface area of Class E airspace designated for an airport. Yes, this is an example of *Class E airspace designated for an airport*. >**Question 4:** >If this is true, what is the ceiling that affects ultralight aircraft? Is it the 700' AGL Class E airspace above the airport? Or does it go all the way up to FL180? In other words, can an ultralight overfly this airport as long as it flies more than 700' AGL? Since §103.17 does not define any vertical limitation, no person may operate an ultralight vehicle anywhere within the lateral boundaries of the surface area of Class E airspace designated for an airport. This prohibition, includes any airspace vertically overlying the Class E surface area, including the Class A airspace at and above FL180. > **Question 5:** >Can an ultralight fly within the two Class E extensions to the Class D airport? Or are these two extensions still considered "surface areas of Class E airspace designated for an airport" (and this has the same answer as question 1 above)? No, these areas are surface areas of Class E airspace designated for an airport. >**Question 6:** >If an ultralight can't fly within these two Class E extensions, can an ultralight flow over these extensions? Is the ceiling 2,700' MSL (same as the Class D airspace of the airport) or is the ceiling 700' AGL (due to the overlying Class E airspace in the area)? Or does it go to FL180 (which would make no sense since an ultralight can overfly the Class D airspace)? No, an ultralight must not be flown over these extensions. [1]: http://www.ecfr.gov/cgi-bin/text-idx?SID=6be1191093a8fd05c00a00f1447459e9&mc=true&node=se14.2.103_117&rgn=div8 [2]: http://www.ecfr.gov/cgi-bin/text-idx?SID=42d3287f504d9d6944b340983b2e755e&mc=true&node=se14.2.101_133&rgn=div8 [3]: http://www.ecfr.gov/cgi-bin/text-idx?SID=0a026d9e5251918e37b2a2683b7a9123&mc=true&node=se14.2.91_1215&rgn=div8 [4]: http://aviation.stackexchange.com/users/62/pondlife [5]: http://aviation.stackexchange.com/a/35299/12720 [6]: https://www.faa.gov/air_traffic/publications/media/pcg.pdf [7]: https://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2006/hucker%20-%20(2006)%20legal%20interpretation.pdf [8]: http://www.ecfr.gov/cgi-bin/text-idx?SID=b70799832ee5e11136f8b6232a872395&mc=true&node=se14.2.91_1303&rgn=div8 [9]: https://www.faa.gov/documentLibrary/media/Order/ATC.pdf [10]: https://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/Interpretations/data/interps/2015/Duncan-AFS-1_4%20-%20%282015%29%20Legal%20Interpretation.pdf