I'd like to clarify a very specific statement from 14 CFR Part 103:

103.17 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.

The specific statement I need help with is:

or within the lateral boundaries of the surface area of Class E airspace designated for an airport

As we know, Class E airspace can start at the surface (shown as a dashed magenta line on sectional charts), start at 700' AGL (shown as a magenta border), start at 1,200' AGL (shown as a blue border), or start at 14,500 MSL.

In the Aeronautical Information Manual (AIM), the following relevant information is given about Class E airspace under section 3-2-6:

e. Functions of Class E Airspace. Class E airspace may be designated for the following purposes:

  1. Surface area designated for an airport where a control tower is not in operation. Class E surface areas extend upward from the surface to a designated altitude, or to the adjacent or overlying controlled airspace. The airspace will be configured to contain all instrument procedures.

(a) To qualify for a Class E surface area, the airport must have weather observation and reporting capability, and communications capability must exist with aircraft down to the runway surface.

(b) A Class E surface area may also be designated to accommodate part-time operations at a Class C or Class D airspace location (for example, those periods when the control tower is not in operation).

(c) Pilots should refer to the airport page in the applicable Chart Supplement U.S. for surface area status information.

  1. Extension to a surface area. Class E airspace may be designated as extensions to Class B, Class C, Class D, and Class E surface areas. Class E airspace extensions begin at the surface and extend up to the overlying controlled airspace. The extensions provide controlled airspace to contain standard instrument approach procedures without imposing a communications requirement on pilots operating under VFR. Surface area arrival extensions become part of the surface area and are in effect during the same times as the surface area.

Part 103 states "or within the lateral boundaries of the surface area of Class E airspace designated for an airport".

That statement has two parts I need help with:

within the lateral boundaries of

and

the surface area of Class E airspace designated for an airport

When looking at a sectional and reading the relevant section of the AIM, what exactly applies to part 103?

I've seen a few attempts to answer the following questions in other forums and it always ends up in a debate including conflicting info from pilots and even FSDO personnel. Is there a clear, definitive "aviation lawyer" legal type answer to the following questions (I'm not concerned with any "should" type discussions here)?

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?

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?

For example (for Q3&4), BLYTHE (BLH) (Phoenix sectional) airport:

enter image description here

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"?

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?

And what about (for Q5&6) Yuma (NYL) (Phoenix sectional) airport:

enter image description here

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)?

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)?

  • Related – Pondlife Feb 6 '17 at 18:51
  • 2
    @Pondlife I rolled back your title edit because it completely changed the focus of my question. – rmaddy Feb 6 '17 at 20:46

NOTE: This answer was originally given based on a conservative interpretation of available interpretations of the regulations. New guidance may shed new light on the issue. The interpretation presented here may be superseded; see the discussion and other answers.


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:

within the lateral boundaries of

and

the surface area of Class E airspace designated for an airport

Here is §103.17 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". Where the totality of an airspace is intended, a comprehensive phraseology is used, such as "within the lateral and vertical boundaries".

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":

§101.33 (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;

§91.215 (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..."

Note: Credit goes to Pondlife for identifying the legal interpretation—Hucker (2006)—that addresses this issue.

The FAA has defined this terminology very clearly and without ambiguity.

The following definition of "surface area" is provided in the Pilot Controller Glossary:

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)—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 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 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), 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.

  • Thank you. This answer agrees with my own understanding. But I was hoping I was wrong. Every other use of "lateral boundary" that I saw in other regs made mention of altitudes just as in your examples. And since 103.17 doesn't, it appears to indicate a needless restriction for ultralights. Why can I fly over a class D airspace but not over an associated class E surface extension to that class D airspace, for example? – rmaddy Feb 7 '17 at 20:56
  • @rmaddy I agree that the regulation seems unnecessarily restrictive when it comes to class E airspace. However, neither do I think that it would make sense to prohibit ultralight flight from the surface to 700 AGL, but allow flight in that same lateral area above 700 AGL, which alternate interpretations would suggest. – J Walters Feb 7 '17 at 21:04
  • Dug into this more, I'm not sure any more whether I agree with the "lateral boundary" part of this answer. Here's why. Sections 91.215(b)(5)(ii), 91.255(d)(3), 101.33(a), and 135.205(b) all use the phrase "the lateral boundaries of" as well as clear altitude delineations. Those are clear. Then there is section 91.303 (aerobatics) which uses the same term. But the only altitude reference is staying above 1500' AGL. We know this means you are allowed to do aerobatics under the outer rings of class B above 1500' AGL. But can you do aerobatics over an airport, above its airspace? Continued... – rmaddy Feb 9 '17 at 17:03
  • And of course section 103.17 with no specific altitude references. So now I can't decide whether a lack of complete altitude references along with "the lateral boundaries of" means surface to outer space or it only means within the altitude range containing the referenced airspace. – rmaddy Feb 9 '17 at 17:04
  • @rmaddy §91.303(c) states "within the lateral boundaries of the surface areas of Class B". If this meant only that portion of the surface area airspace that underlies any above airspace, it would be mostly redundant since §91.303(e) already prohibits aerobatics below 1500 AGL. – J Walters Feb 9 '17 at 17:47

The definitive source for what airspace is where for airports is contained in an FAA Order. That order is updated periodically, and has numerous amendments between issuances. The current order is JO 7400.11B. The order is exhaustive and states on page A-1 that any airspace not defined within is by default Class G.

I submit that your answer is more precisely defined by the above referenced order, and not specifically by a sectional, as the sectional is a derived document from the order.

Using the OP example of Yuma, Appendix E of the order says:

AWP AZ E2 Yuma, AZ Yuma MCAS-Yuma International Airport, AZ (lat. 32°39'24''N., long. 114°36'22''W.) Somerton, Somerton Airport, AZ (lat. 32°36'03''N., long. 114°39'57''W.) That airspace, within a 5.2-mile radius of Yuma MCAS/Yuma International Airport, excluding that airspace from the surface up to and including 300 feet above the surface from lat. 32°36'52'' N., long. 114°41'44'' W.; thence east to lat. 32°36'52'' N., long. 114°39'30'' W.; thence south to lat. 32°34'55'' N., long. 114°39'30'' W.; thence clockwise along the 5.2-mile radius to the point of beginning. The Class E airspace area is effective during the specific dates and times established in advance by a Notice to Airmen. The effective date and time will thereafter be continuously published in the Airport/Facility Directory.

Since the effective date and time are published in the AFD, you would refer to that publication, and also any subsequent NOTAMs. BUT since that description has an exclusion up to 300 feet, you would exclude that area, as Class E does not begin at the surface at those exclusion areas.

A couple of things to keep in mind:

  1. You can overfly with ATC approval.
  2. Class E extends to overlying controlled airspace. I guess that could be Class (A outside continental area?), B, C or Class E beginning at 700 or 1200. It is most often Class E beginning at 700 feet AGL.
  3. When Class E extends to the surface, it is ALWAYS associated with an airport, and there are a list of conditions which apply (WX reporting, com, etc.)
  4. The Class E description is always in the order or addendums.
  • After statement "Using the OP example of Yuma, Appendix E of the order says:", you need to explain that description that follows lies within a section of JO 7400 that is titled as follows: "Class E Airspace Areas Designated as an Extension to a Class D or Class E". Unlike the section that describes the OTHER kind of Class-E-to-surface airspace, that section does NOT bear the title "Class E Airspace Areas Designated as a Surface Area", nor is the title of that section followed by the descriptive sentence "The Class E airspace areas listed below are designated as a surface area for an airport"" – quiet flyer Oct 11 at 22:50
  • Including those details would make your reference to JO 7400 much more meaningful-- but it also might force a substantial rewriting of your answer and even a change in your ultimate conclusions. This statement in particular would need to be deleted-- "When Class E extends to the surface, it is ALWAYS associated with an airport" – quiet flyer Oct 11 at 22:51

Shortest Answer

diagram

Can an ultralight fly within the two Class E extensions to the Class D airport?

Yes

Or are these two extensions still considered "surface areas of Class E airspace designated for an airport"

No

Short Answer

Re the phrase "within the lateral boundaries of the surface area of Class E airspace designated for an airport"--

This phraseology appears in FAR 103.17 (applies to ultralight aircraft), FAR 107.41 (applies to small unmanned aircraft systems, i.e. "drones"), and now also in the newly passed HR 302 which includes regulation of small unmanned aircraft systems which apparently now include all hobbyist radio-control aircraft.

This FAA Memorandum from January 10, 2018 makes it clear that the phrase "within the lateral boundaries of the surface area of Class E airspace designated for an airport" does NOT include the airspace above the ground surface within dashed magenta "extensions" that do NOT actually surround the airport whose approaches they protect-- like this -- .

On the other hand, the airspace above the ground surface within the dashed magenta line on this picture is an example of airspace that IS "within the lateral boundaries of the surface area of Class E airspace designated for an airport".

Here is a video from a school for commercial drone pilots that describes the distinction in plain language for the benefit of students.

The January 10 2018 Memorandum relies heavily on the specific language in FAA Order 7400.11B, "Airspace Designations And Reporting Points", which is the document that legally defines all the different airspace structures that make up the nation's airspace, and precisely delineates their boundaries. The key point is that at the beginning of the part of that document that describes the Class-E-to-surface airspaces that actually surround the airports whose approaches they protect, we find the heading "Class E Airspace Areas Designated as a Surface Area", followed by the descriptive sentence "The Class E airspace areas listed below are designated as a surface area for an airport." We don't find the same language at the beginning of the part of the document that describes the "extensions".

The January 10 2018 Memorandum is in relation to unmanned autonomous vehicles, but since FAR 103.17 uses the identical phraseology, ("within the lateral boundaries of the surface area of Class E airspace designated for an airport"), the only logical conclusion is that ultralight aircraft CAN fly over those dashed magenta Class-E-to-surface "extension" areas with no special permission.

If there are past FAA rulings/ interpretations that contradict the January 10 2018 Memorandum referenced above, or contradict the implications in relation to ultralight aircraft that I've drawn from the January 10 2018 ruling, and which would therefore suggests or rule that ultralight aircraft are NOT allowed to fly over Class-E-to-surface "extensions" that do not actually envelope the relevant airport without special permission -- please add links to those documents to this post.

The precise meaning of the phrase "within the lateral boundaries of the surface area of Class E airspace designated for an airport" also bears on where we may operate under "Special VFR", and where we must have a "Special VFR" clearance if the ceiling is below 1000' AGL. See this answer to the question "Does FAR 91.155c apply to class E surface extensions?" for more.

It is possible that we will see some FAA rulings that impact on these topics in the near future. As things stand right now, there appears to be a loophole in regulations that will go into effect in the near future (HR 302) regarding Small Unmanned Aircraft (radio-controlled airplanes and "drones"), which will allow SUA's to operate above 400' altitude without "prior authorization from Air Traffic Control" ONLY if they are in Class-E-to-surface "extensions", and nowhere else in the nation's airspace-- except perhaps in Class E not-to-surface airspace that was entered from a Class-E-to-surface "extension", or after climbing above the top of the Class E floor while flying "with prior authorization" in Class B, C, or D airspace or while flying with "prior authorization" in Class-E-to-surface airspace of the "designated for an airport" variety. It is unlikely that this is what was intended. There are at least two logical ways to fix the problem: 1) extend the 400' AGL limit (in the absence of "prior authorization") to all airspace, not just Class G, or 2) explicitly include all Class-E-to-surface airspace including "extensions" in the airspace in which "prior authorization" is needed. However, it is possible that the FAA will simply bludgeon the issue into submission and overrule the January 10 2018 memorandum, however well-founded it may be, by ruling that the meaning of "within the lateral boundaries of the surface area of Class E airspace designated for an airport" DOES include the Class-E-to-surface extensions.

Now read on for much more--

How to better understand the rationale behind the January 10 2018 Memorandum?

The January 10 2018 document explicitly cited the FAA's "Airspace Designations And Reporting Points", JO 7400.11B . (Replaced in August 2018 by Order JO 7400.11C, which has no changes of significance to this question. Page references in this answer are to the August 2018 edition.) This document clearly divides Class-E-to-surface airspace into two different types--

One type is identified on page vii: "Class E Airspace Areas Designated as a Surface Area" . On page E-1 this heading is repeated, followed by the descriptive sentence "The Class E airspace areas listed below are designated as a surface area for an airport". When one reads the actual individual airspace descriptions, it is clear that each of these particular Class-E-to-surface airspace areas actually surrounds the airport whose approaches it protects.

The other type is identified on page ix -- "Class E Airspace Areas Designated as an Extension to a Class C Surface Area" and on page x -- "Class E Airspace Areas Designated as an Extension to a Class D or Class E Surface Area". On page E-141 we find the shorter heading "Class E Airspace Areas Designated as an Extension", followed by the descriptive sentence "The Class E airspace areas listed below consist of airspace extending upward from the surface designated as an extension to a Class C surface area." Similar language is repeated on page E-156 in regard to extensions to Class E airspace areas. When one reads the actual individual airspace descriptions, it is clear that none of these Class-E-to-surface airspace areas actually surrounds the airport whose approaches it protects. Nowhere in these parts of JO 7400 do we find the phrase "designated for an airport".

And what is the precise language of FAR 103.17?

"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."

The casual reader of FAR 103.17 and FAR 107.41 might wonder whether the phrase "designated for an airport" really has any significance. Is this phrase really meant to distinguish the type of class-E-to-surface airspace that surrounds an airport whose instrument approaches it protects, from the type that is merely an "extension" that abuts up against the airspace of the airport whose instrument approaches it protects?

In the light of the precise language of Order JO 7400 as noted above, the answer has to be an unambiguous "yes"-- and that is exactly what the FAA found in the January 10 2018 Memorandum.

The phrase "surface area" in FAR 103.17 and FAR 107.41 could be said to be a "loaded" phrase as well. Does this mean "designated as a Surface Area", as used in FAA Order JO 7400 for the title of the section that describes the type of Class-E-to-surface airspace that actually surrounds the airspace whose approaches it protects? Or are we just noting that the bottom of the airspace happens to be in contact in the ground? Regardless of which interpretation we choose, the inclusion of the phrase "designated for an airport" is enough to leave no doubt as to which type of Class-E-to-surface airspace FAR 103.17 and FAR 107.41 are referring to.

It's also worth taking a look at the AIM (Aeronautical Information Manual).

The AIM uses the phrases "designated for an airport", "surface area", and "surface area designated for an airport" ONLY in relation to the type of Class-E-to-surface airspace that surrounds the airport whose instrument approaches it protects, and NOT in relation to Class-E-to-surface "extensions".

Specifically:

Page 3-2-9

e. Functions of Class E Airspace. Class E airspace may be designated for the following purposes:

  1. Surface area designated for an airport where a control tower is not in operation. Class E surface areas extend upward from the surface to a designated altitude, or to the adjacent or overlying controlled airspace. The airspace will be configured to contain all instrument procedures.

(a) To qualify for a Class E surface area, the airport must have weather observation...

(b) A Class E surface area may also be designated to accommodate part-time operations at a Class C or Class D airspace location (for example, those periods when the control tower is not in operation).

  1. Extension

  2. Extension to a surface area. Class E airspace may be designated as extensions to Class B, Class C, Class D, and Class E surface areas. Class E airspace extensions begin at the surface and extend up to the overlying controlled airspace. The extensions provide controlled airspace to contain standard instrument approach procedures without imposing a communications requirement on pilots operating under VFR. Surface area arrival extensions become part of the surface area and are in effect during the same times as the surface area.

That very last sentence does seem to create some ambiguity. Bear in mind that the AIM is not a legal document in the sense that the FAR/CFR is. Stating that the surface arrival extensions "become part of the surface area" does not necessarily mean that all regulations applying to the "Surface area designated for an airport" also apply to the Class-E-to-surface airspaces "designated as extensions to Class B, Class C, Class D, and Class E surface areas". Certainly the FAA didn't see it that way when issuing the January 10 2018 Memorandum.

Now let's take a look at the FAA's Pilot Controller Glossary. Does the Pilot/Controller Glossary define a "Surface Area"? Yes it does-- "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." Again, this "designated for an airport" terminology is exactly the same language that we find in Order JO 7400. This further supports the idea that the FAA intends the phrase "surface area" to be used only in relation to the type of Class-E-to-surface airspace that surrounds the airspace whose approaches it protects, and not in relation to the Class-E-to-surface "extensions".

Some have suggested that the phrase "designated for an airport" in FAR 103.17 is superfluous, and is not meant to differentiate between the two different types of Class-E-to-surface airspace, because the FAA uses similar language in some cases in reference to Class B or Class C airspace. This overlooks looks the point that the FAA's "Airspace Designations And Reporting Points", Order JO 7400, specifically uses this phrase to differentiate between the two different types of Class-E-to-surface airspace, as discussed above. The phrase "designated for an airport" does not appear in that document's description of Class B or Class C airspace, so the phrase likely is indeed superfluous in reference to such airspace. Why then does the phrase appear in any FAA material describing such airspaces? It probably was put there by someone who wanted to specifically refer to the part of that airspace whose base was at ground level, and copied from other sources language referring to Class-E-to-surface airspace, without appreciating the significance of the phrase "designated for an airport" in that context.

Is there an altitude limit to the concept of "within the lateral boundaries of the surface area of Class E airspace designated for an airport"?

The FAR's clearly specify that Class E airspace continues upward until it runs into some other higher category of airspace. It seems clear enough that the concept of "within the lateral boundaries of the surface area of Class E airspace designated for an airport" has no upward limit AT ALL. Basically we are just saying that the aircraft occupies some point in the sky that is above the ground-level "footprint" that is demarcated by the dashed magenta lines on the chart.

Some pilots seem to imagine that the phrase "within the lateral boundaries of the surface area of Class E airspace designated for an airport" means the airspace within, but NOT HIGHER THAN THE TOP OF, the lowermost vertical (cylindrical) green wall on this diagram: (taken from http://footflyer.com/PPGBibleUpdates/Chapter08/AirspaceQuestion/AirspaceQuestion.htm )

I.e. the airspace that would be "held in" within the lowermost wall depicted, as if it were the wall of a moat holding in a body of water. In other words, if the innermost wall between the class E and class G airspace were somehow made visible, the pilot would only be considered to be "within the lateral boundaries of the surface area of Class E airspace designated for an airport" if he could look out horizontally while flying, and see the lower-most, innermost wall.

That interpretation is completely implausible. It is impossible to imagine that the rules for Special VFR operations-- only one aircraft allowed to be IFR or VFR within the class-E-to-surface airspace, etc-- would be confined to this area less than 700' above the ground. And are we to imagine that under the text of FAR 107.41, which contains the EXACT SAME "within the lateral boundaries of the surface area of Class E airspace designated for an airport" verbiage, that it is perfectly legal to fly a drone at 701 feet over the surface of an airport surrounded by the dashed magenta circle, with no prior authorization? Surely not.

Also, a close look at FAA order JO 7400 reveals that in cases of Class D airspace that revert to Class-E-to-surface where the tower is not open full time, we are given two different descriptions of that airspace in JO 7400. The description in the Class D section has a prescribed altitude limit (typically around 2500' AGL), while the description in the section entitled "Class E Airspace Areas Designated as a Surface Area" has no specific prescribed altitude limit.

Finally, consider this: FAR 101.33 states:

"§101.33 Operating limitations. No person may operate an unmanned free balloon—

(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

If the phrase meaning of the phrase "within the lateral boundaries of the surface areas of Class E airspace designated for an airport" only extended to 700' AGL, it would be perfectly legal for an unmanned balloon to be at 701' in this area with no prior authorization, despite the regulation, and there would be no reason to include any reference to Class E airspace of any kind in the regulation.

What happens when the tower closes?

It is very clear based on FAA order JO 7400 that in most cases where the relevant control tower in class C or class D airspace is not open full time, the "surface" portion of the class C or class D airspace reverts the type of to Class-E-to-surface airspace that is called a "Class E surface area" in the AIM or a "Class E Airspace Area[s] Designated as a Surface Area for an airport" in FAA Order JO 7400. AIM 3-2-10 indicates that it is also possible for Class C or Class D airspace to revert to Class G airspace during the hours the tower is closed, but this is rare. Whenever Class D (or higher) airspace reverts to Class-E-to-surface airspace, this airspace has NO upward limit other than the floor of the next higher airspeed class above. Since ultralights are prohibited (without special permission) from flying over the type of Class-E-to-Surface airspace that is not an "extension" but rather surrounds the airport whose approaches it protects, this has the odd consequence of prohibiting an ultralight aircraft from flying (without special permission) directly above what would have been the ceiling of the Class D airspace when the tower was open, while allowing the ultralight to fly directly over that same Class D ceiling when the tower is open.

What happens when weather at the airport is above VFR minimums?

Nothing changes-- ultralights still need "prior authorization" to enter Class-E-to-surface airspace "designated for an airport", i.e. surrounding the airport whose approaches it protects. Nothing in the FAR's or AIM supports the idea that the Class-E-to-surface airspace is only "effective" during certain weather conditions, such as when the weather is so bad that VFR aircraft need an authorization for flight under Special VFR rules. This sort of terminology may be common in the ATC community, which will tend to be focussed on the need to make sure that not more than one aircraft is operating under IFR or Special VFR rules at a time within this airspace, but it is not strictly supported by anything in the FAR's or AIM. (Note: at least one FAA official at a FSDO has responded to an ultralight pilot's request for clarification on this topic by stating something to the effect that "Class-E-to-surface airspace is only active under VFR minimums. During VFR times, act as if it doesn't exist." There is other anecdotal evidence that in the past, some FSDO's have taken this approach and had no problem with ultralight operations in Class-E-to-surface airspace in good weather. This is not particularly surprising. Consistency has not been the FAA's forte on these topics, especially on the level of the FSDO's, ATC facilities, etc. Don't take this note to mean that there have not also been interpretations, possibly even official legal interpretations, to the contrary. It's pretty clear from the FAR's and the AIM what the real truth is here. )

This is the end of the main body of the answer

But read on if you want to learn how the terminology relating to Class-E-to-Surface airspace has evolved over time

To really understand how the whole concept of Class-E-to-surface airspace came about, and how this relates to the language in FAR 103.17 and 107.41, it helps to take a trip back through time.

FAR 103 was adopted July 30 1982.

Originally, FAR 103.17 said that "No person may operate an ultralight vehicle within an airport traffic area, control zone, airport radar service area, terminal control area, or positive control area unless that person has prior authorization from the air traffic control facility having jurisdiction over that airspace".

So what was a "control zone"?

"Control Zones" first appeared on charts in the mid-1940's and consisted of a thin dashed circle enclosing an airport-- originally red, later blue. By the time of this 1974 test-prep publication, control zones had been defined to go up to the overlying "Continental Control Area" at 14,500' MSL. At that time, most (but not all) towered airports had Control Zones around them, and some non-towered airports did too. By that time, special requirements in effect within a Control Zone included 3 miles visibility and a ceiling of at least 1000', unless a pilot was granted permission to fly under "special VFR" rules. Also by that time, an "Airport Traffic" area was a different thing from a "Control Zone", requiring radio communication with the tower for entry, with a smaller, standardized diameter and a much smaller, standardized vertical height. "Airport Traffic Areas" were not even depicted on sectional charts, because they were automatically present at all towered airports, and they were standardized in diameter and height. Even though Airport Traffic Areas weren't depicted on sectional charts, they were referenced on the chart legend through at least mid 1983 in the language concerning towered airports, but by sometime in late 1988 that reference had been dropped.

Bear in mind that a "control zone" is only a small subset of the larger concept of "controlled airspace". In charts dating at least back through 1969, we can see the blue shadings and magenta shadings showing whether the floor of the "controlled airspace" starts at 700' or 1200', outside of the dashed blue "control zones"-- as well as other markings to show other cases where the floor of the "controlled airspace" is at some other, higher altitude. So staying out of "control zones" has never been synonymous with staying out of all "controlled airspace"-- at least in the time period we're discussing here. From the viewpoint of a VFR pilot, entering into the most basic level of "controlled airspace" simply imposes a change in cloud clearance and visibility requirements.

Not until mid-to-late 1992 do we see dashed magenta lines (as opposed to magenta shading) appear on sectional charts. Originally, the chart legend for the dashed magenta line read as follows: "Control Zone at airport without control tower and Control Zone extension without communications requirement". The charts now contained dashed magenta lines that encircled the airports whose instrument approaches they protected-- this would be a "Control Zone at airport without control tower"-- as well as dashed magenta extensions abutting dashed blue lines encircling airports, or abutting higher classes of airspace such as TRSA's-- these would be "control zone extensions" and not actually "control zones". Presumably the "without communications requirement" applied in both cases. So now for the first time we have two different kinds of airspace enclosed by dashed magenta lines. We also still have control zones depicted by dashed blue lines-- by this time, those control zones did have a communications requirement, since one of their functions was to fill the role of the old "Airport Traffic Area". At the same time that the control zones (and control zone extensions) depicted by dashed magenta lines appeared on the chart, the charts started showing a designated, individualized ceiling for each control zone depicted by a dashed blue line, typically around 2500 AGL. This was a step toward the evolution of the current "Class D" airspace. No specific ceiling was shown on the chart for the control zones depicted by a dashed magenta line or for the control zone extensions depicted by a dashed magenta line.

FAR 103.17 never was modified to prohibit ultralights from entering "control zone extensions" without prior authorization from ATC.

In late 1993 the nation's airspace went through a substantial change in nomenclature, along with some changes in structure-- this when the current system of Classes A, B, C, D, and E came into use. By November 1993, all reference to "control zones" and "control zone extensions" vanished from the sectional charts. Now the chart legend simply said "Class D airspace" for the dashed blue lines and "Class E airspace" for the dashed magenta lines. The latter isn't terribly descriptive, given the abundance of Class E airspace-- the pilot was simply expected to understand that this was specifically a reference to the nature of the airspace right at the very surface of the earth.

Sometime around this time was when the FAA's Order 7400, "Airspace Designations And Reporting Points", was revised to delete all references to control zones. This is when we get the awkward terminology in the headings of this document. The heading of the section describing the type of Class-E-to-surface airspaces that surround the airports they protect is "Class E Airspace Areas Designated as a Surface Area". Wouldn't they have done better to title this section something like "Class-E-to-surface airspace areas designated for an airport"? The term "Surface Area" is inherently somewhat confusing, since the Class-E-to-surface "extensions" also go all the way down to the surface. As we've already noted though, the descriptive text following the titles clears things up-- the heading "Class E Airspace Areas Designated as a Surface Area" is followed by the descriptive sentence _"The Class E airspace areas listed below are designated as a surface area for an airport". We don't find this language attached to the headings for the Class-E-to-surface "extensions".

Around the same time-- specifically on September 16, 1993-- the text of FAR 103.17 was changed to include the current "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."

Note: where italization appears in quoted material in this answer, the italization did not appear in the original source material, but rather was added to help clarify the discussion.

that's all

  • Here's a PDF to the memorandum that includes the attachments. It is much clearer than the PNG. goldsealgroundschool.com/uav-library/… – rmaddy Oct 4 at 17:51
  • Here's a video that talks about this memorandum which seems to clarify it some. youtube.com/watch?v=Ln7hTVc8N1k – rmaddy Oct 4 at 17:52
  • This memorandum is specific to part 107 (Drones), not part 103 (Ultralights) so you can't blindly assume it applies to part 103. Also, this memorandum makes no attempt to clarify what "within the lateral boundary of" means. It doesn't clarify the altitudes involved. It doesn't clarify if we can fly over this class E airport and its surface area. At best it clarifies which class E surface areas are being addressed. – rmaddy Oct 4 at 17:56
  • About your "PS". I agree the wording seems to mean we can't fly over a class E airport with a surface area. But in real life that makes little sense. Why can I fly directly over a class B, C, or D airport but not a class E airport? It's silly. I mention this because other parts of your answer suggest that this clarification to part 107.41 should logically apply to part 103.17. A rule is a rule regardless of logic. – rmaddy Oct 4 at 18:22
  • rmaddy re your last comment, I don't follow why you think I'm treating UAV's and ultralights differently. I meant my all comments to apply equally to both. Re your second-to-last comment, the key point is that the phraseology used ("within the lateral boundaries of the surface area of Class E airspace designated for an airport") is EXACTLY the same in both sets of regs. – quiet flyer Oct 4 at 19:10

18-1-2. CLASS E SURFACE AREAS

Class E Surface area extend upward from the surface to a designated altitude; or to the adjacent or overlaying controlled airspace


103.17 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

*** The within the lateral boundaries = this means the area inside the dashed magenta. The dashed magenta line does not exist past certain altitudes. = to a designated altitude; or to the adjacent or overlaying

Example- If referring to a non towered airport, the dashed magenta line (lateral boundary) stops at 700' agl. (Its all Class E, it's now Class E 700' boundary. This means there is no longer a surface area boundary past that altitude)

You can fly over the dashed magenta above 700' agl because thats the "designated altitude" and its no longer a "surface area". It is now Class E 700, then that lateral boundary stop at Class E 1200.

Below 700' agl you would be crossing the dashed magenta (lateral boundaries) that exists below 700' and operating within.

Cant remember where I got this from, helps explain rather well.

Class E Airspace: Controlled airspace is officially defined by exclusion, which often does not tell you much. By that reasoning, Class E airspace is controlled airspace that is not Class A, B, C or D or G (explained below) airspace. Not too helpful, but you can be sure that there is a lot of Class E airspace, so much that one could think of it as "E" for Elemental or Everywhere airspace, the airspace out of which all other types are carved. It is the filler that fills in under Class A, ie; below 18,000' msl, and between Classes B,C and D and over the top of Class G (described below). Its volume is vast. If we ignore the upper cover of Class A airspace, it is safe to say that there is a lot more E than all the other kinds combined. Ultralights fly freely in most of Class E space with one exception described below.

Class E almost always has one of four lower limits: those being surface, 700' AGL, 1200' AGL, or 14,500' MSL (discussed below). Most of the country has a Class E lower limit of 1200' AGL. Where it drops to 700' AGL it is shown by a broad magenta line with a fuzzy side. The fuzzy side is the side where the floor of Class E is 700' AGL. The floor may also drop to the surface where it is called "Class E Surface Area". A dashed magenta line indicates the boundary of the Class E Surface Area. So on the image, you can see the dashed magenta line around the airport indicating the outer boundary of the Class E Surface

enter image description here

Class E Surface Areas and Floors

Area and outside of that a meandering wide magenta line showing where the floor of Class E goes from 700' agl to 1200' agl as you go away from the airport.

The major exception to ultralights being allowed in Class E Airspace is: FAR, Part 103.17 -- "No person may operate an ultralight vehicle within [snip] 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."

"Class E Surface Area," looks much like Class D but only in dashed magenta, not dashed blue. Notice there is no upper altitude number within a box like there was in Class D. The question then becomes... what is the upper limit? How is this airspace boundary defined?

The FAA has a definition for "Class E Surface Area" that includes an upper limit. It is the height of the surrounding Class E floor just outside the lateral boundaries of the Class E Surface Area. For example in the image (above), the upper limit of Class E Surface Area is 700' agl meaning you could fly your ultralight vehicle over this airport but you must remain at least 700' agl as you fly over. fly over.

enter image description here

  • In all my time flying through Class E airspace that extends to the surface, I have never encountered a dashed magenta line. My understanding is that these exist on the two-dimensional sectional chart only, and do not have any vertical dimension. – J Walters Feb 7 '17 at 19:54
  • @JWalters they are depicted as a two dimensional area on the chart, but they have height, and when associated with an airport, which is the only instance that Class E begins at the surface, they have a volume by virtue of their extension upward to the underlying controlled airspace. Most of the time that airspace is Class E, beginning at 700 feet AGL. – mongo Oct 24 '17 at 18:40
  • Hi Mike. We've gone round and round about this on another forum. This is just not accurate at all. Specifically the statement "The FAA has a definition for "Class E Surface Area" that includes an upper limit. It is the height of the surrounding Class E floor just outside the lateral boundaries of the Class E Surface Area." Admittedly the some of the FAA definitions are written in rather obtuse language-- hence my very long answer exploring that language--- but your interpretation is not correct. I recognized your argument long before I noticed the name at the end and it just won't fly. – quiet flyer Oct 12 at 9:09
  • As someone else said in another comment on another related forum aviation.stackexchange.com/questions/35407/…, "within the lateral boundaries of" has no implied altitude restriction. That term, in English, implies surface to outer space". Or are we to believe that they were only banning aerobatics below 700' AGL, as far as the Class-E-to-surface is concerned? Something to think about-- – quiet flyer Oct 12 at 9:11
  • Noting that "within the lateral boundaries of the surface area of Class E arpce dsgntd for an airport" appears in both FAR 103.17 and FAR 107.41 (pertains to Small Unmanned Aircraft), one could use one of the on-line forums for commercial drone operators a sounding board for ideas like "we're fine to overfly Class-E-to-surface surrounding an airport at 701'", or "the dashed magenta lines not in effect if the wx is above standard Class E minimums". Read more: forum.hanggliding.org/… Unmanned Aircraft – quiet flyer Oct 12 at 15:14

protected by Community Aug 10 '17 at 13:01

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