Let's discuss-- Part 103.17-- ultralight flight in Class-E-to-surface "extensions"

[quietflyer]

Some time has passed since this thread has last been active.

My thoughts have changed a little, but not much--

In JO 7400.11C (the "Airspace Designations and Reporting Points" document), the AIM, the Pilot-Controller glossary, and many other places, the FAA seems to have acquired the habit of using the phrase "Surface Area" or "surface area" in a rather strange way, referring to an actual chunk of airspace with a vertical dimension as well as a horizontal dimension. Furthermore, many examples can be found where the horizontal extent of the airspace named as a "Surface Area" or "surface area" is construed not to include E4 Class-E-to-surface "extensions". The "Airspace Designations and Reporting Points" document is one such example.

Nonetheless, the plain language of FAR 103.17 and many related regulations suggests that within the context of those regulations, "surface area" simply means the surface footprint of a given column of airspace whose bottom is in contact with the surface. For example other regulations suggest that class B or class C airspace also can have a "surface area", even though this term is not used in JO 7400.11C in relation to these airspace types. "Within the lateral boundaries of the surface area" simply means any airspace above the surface footprint of a given column of airspace whose bottom is in contact with the surface, without regard to altitude. In this context, if we were discussing the "surface area of Class E airspace" near a given airport, it would not seem incongruent to assume we were including any adjacent E4 "extensions", despite the fact that JO 7400.11C and numerous other FAA materials follow a different practice. All things considered, it would seem to be a matter of some ambiguity-- a conflict between what the plain language of the FARs seems to suggest on first reading, and what is suggested by the convention followed in JO 7400.11C and other FAA materials in reference to Class E airspace in particular.

If we do embrace the idea that the use of the term "surface area" does not automatically exclude E4 "extensions" in the context of FAR 103.17 and other FARs with similar language, the critical point then boils down to the phrase "designated for an airport". While this phrase seems to have been superfluously retained in several recent regulations that don't even address Class E airspace (for example FAR 91.225 (e)(2)), it seems to have originally appeared in the post-"Alphabet" re-organization (post September 1993) version of FAR 103.17 and other regulations with related language as a way to indicate that the only type of Class-E-to-surface airspace encompassed by the said regulation was E2 airspace. E4 "extensions" were not meant to be included. E2 airspace is the only kind of Class-E-to-surface airspace that is named or described in the "Airspace Designations and Reporting Points" document as being "designated for an airport". If this distinction were not intended, there would have been no reason to include the phrase "designated for an airport" or any other similar phrase in FAR 103.17 and other regulations with similar language; it serves no other purpose whatsoever.

This understanding is consistent with the understanding expressed in the 2010 response from the FAA ATO Western service center re obtaining SVFR clearance in E4 "extensions" as referenced in post #30 http://eaaforums.org/showthread.php?...ll=1#post75340 , and the January 10 2018 FAA internal memo from Scott Gardner re sUAS (commercial drone) operations in E4 "extensions" (old link not working at present -- instead see https://jrupprechtlaw.com/section-10...rtain-airspace ). In both cases, E4 airspaces were understood NOT to be encompassed by the language of the relevant regulations, which had language similar to (in the former case) or identical to (in the latter case) the language of FAR 103.17.

It will be interesting to see whether the FAA continues to stay consistent with this line of reasoning in the future. There are some ambiguities in new rules regarding recreational sUAS operation (recreational model airplanes and drones) that they'll need to address one way or another. So, stay tuned.

Steve