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

[quietflyer]

Also consider this-- there are a few airports where we find a central Class E (not Class D) core, with Class E extensions. (Many Class D airports also revert to this configuration when the tower closes for the night, but let's focus for now on the ones where there is no Class D at all.) Here's one example-- KTLV -- http://vfrmap.com/?type=vfrc&lat=38....19.995&zoom=10 . In fact, this example was specifically addressed in one of the attachments to the January 10 2018 Gardner memo I've been referencing in post #21 and elsewhere -- stating that prior authorization was not required by FAR 107.41 for drone operations in the extension.

But independent of the Gardner memo, I'd pose the following question-- if AIM 3-2-6 is truly accurate in stating that "Surface area arrival extensions become part of the surface area" whenever the surface area is in effect, then wouldn't it be fair to say there is no functional difference of any kind whatsoever between the rectangular class-E-to-surface extension and the round Class-E-to-surface circle at KTLV? Whether we are talking about SVFR operations as prescribed by FAR 91.155c and 91.157, or drone operations as prescribed by FAR 107.31, or ultralight operations as prescribed by FAR 103.17, if the airspace within the extension is really considered to be "within the lateral boundaries of the surface area of Class E airspace designated for an airport", it would seem to not make any difference at all whether an aircraft was within the dashed magenta circle or the dashed magenta rectangular extension. If this is what is intended, why have the dashed magenta line separating the two units of airspace? Why not just have a single piece of airspace, like we see at KONP ( http://vfrmap.com/?type=vfrc&lat=44....24.058&zoom=10 ) ? There must be a reason for the distinction.

At KTLV-- but not at KONP-- the airspace in the rectangular portion is described in a separate portion of JO 7400-- the portion starting on page E-156 under the heading "6004. Class E Airspace Areas Designated as an Extension to a Class D or Class E Surface Area", rather than in the portion staring on page E-1 under the heading "6002. Class E Airspace Areas Designated as a Surface Area". Hence the dashed magenta line separating the two portions at KTLV, but not at KONP.

It sure looks to me that at KTLV and other airports with similar airspace configurations, there must have been a desire for the "extension" to function differently in some way than the airspace in the "Surface Area" in the dashed circle. Such as, in some way relating to SVFR operations and/or part 103 ultralight operations and/or part 107 sUAV operations, or perhaps in some other way relating to instrument approach procedures. But if AIM 3-2-6 were really accurate in stating that "Surface area arrival extensions become part of the surface area" whenever the surface area is in effect, it seems that no such distinction would exist, and there would be no reason to ever create an airspace configuration like we see at KTLV, as opposed to what we see at KONP.

Even if there is standard guidance in place that if the rectangular portions protecting the approaches extend more than X miles from the main circle then they are to be designated as "extensions" rather than as part of the inner surface area, why would they bother to draw the dashed line separating the two areas on the sectional chart for KTLV unless there were some functional difference between the two airspaces? I can't imagine how there could be any functional difference-- especially any functional difference pertaining to VFR pilots-- unless the airspace above the "extensions" were NOT considered to be ""within the lateral boundaries of the surface area of Class E airspace designated for an airport".

Steve