May the Class-E-to-surface designation indicated by the dashed magenta lines outside the dashed blue circle at Eagle County Regional airport (KEGE) be ignored when the tower is open?
Likewise at Marshall AAF (KFRI)?
Normally we would consider a dashed magenta line that does not actually enclose the airport whose approaches it protects to denote a Class-E-to-surface "extension", i.e. E4 airspace. The "extension" would be described in the E4 section of the "Airspace Designations And Reporting Points" document (FAA Order 7400.11C), typically with no comment about effective hours. Meanwhile, if the tower is not open 24 hours, the area in the dashed blue circle will be typically described in the Class D section of Order 7400.11C and ALSO in the E2 section of 7400.11C, with a note in each section to see the A/FD for the effective hours of that designation.
Here is an example of an airport with airspace designated in this manner: KMFR. The relevant pages in JO 7400.11C are E-80, E-189, and D-65. The dimensions of the E-2 airspace are identical to the dimensions of Class D airspace, except for the absence of any altitude ceiling on the Class D. The E-4 "extensions" are in effect 24/7, whether the tower is open or closed.
But at KEGE and KFRI that's not what was done. There is no listing for the airspace within the dashed magenta line in the E4 section of JO_7400.11C.
Instead, a single area of Class-E-to-surface "Surface Area designated for an airport", i.e. E2 airspace, is defined that includes the area in the dashed blue circle AND the area in the dashed magenta line that abuts the dashed blue circle. (Page E-70 KEGE, page E-16 KFRI).
There's a note that the dates and times that the E2 will be in effect will be published in the A/FD: for example, for KEGE we read "This 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. AMENDMENTS 11/23/06 71 FR 46077 (Revised)"
Naturally, the airspace in the dashed blue circle is also described in the Class D section of Order 7400.11C (page D-59 KEGE, page D6 KFRI), with a note to see the A/FD for the effective times.
The A/FD (for KEGE) says "AIRSPACE: CLASS D svc 1400–0200Z‡; other times CLASS E."
No E4 airspace has been designated for KEGE or KFRI.
So the area in the dashed blue circle is Class D when the tower is open and E2 when the tower is closed. And the area enclosed by the dashed magenta line, has, oddly, been designated not as E4 airspace as per normal practice, but rather as part of the same E2 airspace that is only in effect when the tower is closed. So it seems that the entire E2 airspace should vanish when the tower is open, and should therefore simply become Class G up to 700' AGL.
Surely this is not what is actually intended.
Is the intention that the area inside dashed magenta border but outside the dashed blue circle stays E2 the whole time, while the area inside the dashed blue circle and below 9100' MSL at KEGE or below 3600' MSL at KFRI falls out of the E2 as if it were cut with a cookie cutter, and turns into Class D, when the tower is open?
Here's one problem with that idea--
There are about twenty other airports in the US where the airspace designation is similar to KEGE and KFRI, but a little different. One such example is KUNV-- University Park at State College PA-- --for the others, see this related answer: What are all the US airports where E4 "extensions" change to E2 and become part of a larger E2 "surface area" when the tower closes for the night?.
Taking KUNV as an example, the airspace enclosed by the dashed magenta lines is designated in order 7400.11C (page E-171) as E4 airspace, with a note to see the A/FD for the effective hours. There's ALSO a designation of E2 airspace (page E-37) that includes the exact same airspace AS WELL AS the area in the dashed blue circle, with a note to see the A/FD for the effective hours. And the area in the dashed blue circle is also described in the Class D section of Order 7400.11C (page D-23), with a note to see the A/FD for the effective hours.
The note in the A/FD simply says "AIRSPACE: CLASS D svc 1100–0300Z‡; other times CLASS E."
Clearly, in this case it was felt that the entire E2 airspace would vanish as a single unit when the Class D airspace was in effect, hence the need to also have an E4 airspace designation to protect the airspace in the dashed magenta projections when the tower is open.
The same situation applies at the other 20 airports listed in the linked answer.
Added note-- it is interesting to note that on the FAA's LAANC map for authorization for sUAS (drone, model airplane) flight the projecting "extensions" at KEGE and KFRI are NOT covered by the grid squares that indicate the areas where pre-authorization is required. All other E2 airspace IS covered by the grid square that indicate that pre-authorization is required, EXCEPT for part-time E2 airspace that changes to E4 whenever the adjacent control tower is open, i.e. the twenty or so airports described above. This tends to suggest that the airspace within the dashed magenta line at KEGE and KFRI is not treated as E2 airspace when the tower is open, at least in relation to FAR 107.41. However this doesn't really bear on whether this airspace still functions as some form of Class-E-to-surface airspace when the tower is open in relation to other FAR's. One shouldn't read too much into the depiction on the LAANC map.
See also this related question: May an ultralight vehicle pass directly above KEGE at 9200 MSL at 1600Z with no prior authorization without violating FAR 103.17?
Are there any other airports where the airspace designations have been set up similar to KEGE and KFRI?
