The August 1992 Final Rule "Terminal Airspace Reconfiguration" (page 38963, Federal Register Volume 57 No 167, August 27 1992) (link to pdf of entire issue opening to this page) stated that the purpose of "control zones" was as follows:
A control zone ensures that aircraft arriving at an airport under IFR remain within controlled airspace when an instrument approach procedure could put that aircraft within 1000 feet of the surface. A control zone also ensures that aircraft departing an airport under IFR remain within controlled airspace between the surface and the base of adjacent controlled airspace.
The same Final Rule also makes clear (pp. 38963-38964) that surface level controlled airspace, including surface-level Class E airspace, would serve the same purpose after September 16 1993 as control zones served prior to that time.
With this in mind, why was it necessary to designate such a large area of surface-level Class E airspace at SIT/PASI airport at Sitka, Alaska? (Pictured above.) The E4 surface-level Class E "extension" is 12 miles wide, and extends to 28.3 miles northwest of the airport. (See page E-158 of the "Airspace Designations and Reporting document FAA Order 7400.11F; this airspace was last modified 11-05-2020.)
Is it really true that there are instrument procedures for this airport that could put an aircraft below 1000' AGL in all or most of this airspace? If so, which procedures are those?
Or does the FAA now designate surface-level controlled airspace based on some criteria other than the one stated above?
Wouldn't an aircraft flying over the Pacific Ocean northwest of the northwest tip of Kruzof Island, inbound for landing at SIT/PASI, flying below 1000' AGL/MSL, be in great danger of colliding with the high terrain (over 2350' MSL) near the northwest tip of Kruzof Island? Is there really any instrument procedure that could have an aircraft on approach for SIT/PASI below 1000' AGL/MSL at this location? If not, was there really any reason to extend the "extensions" much beyond the (approx) 2350' MSL terrain near the northwest tip of Kruzof Island? Based on the criteria stated above, was it really even necessary to extend it that far?
Has the E4 surface-level Class E "extension" in this area simply been sized to to completely contain some particular instrument procedure, regardless of whether or not an aircraft following that procedure might be within 1000' of the terrain (or ocean) in all parts of that "extension"?
Wouldn't much of the airspace covered by the E4 surface-level Class E "extension" extending 28.3 miles northwest of the airport be adequately be protected by a "transition area" with a Class E floor at 700' AGL, or by the existing surrounding Class E airspace floor at 1200' AGL?
This latter, more "conservative" approach would avoid imposing certain restrictions associated with surface-level controlled airspace on various aviation activities, such as the prohibition on VFR flight below a ceiling of 1000' AGL or lower without a Special VFR clearance (FAR 91.155(c)), the requirement for three miles visibility for taking off or landing (FAR 91.155(d)) (consider seaplane operations in this context), the requirement for ½-mile daytime, 1-mile nighttime visibility for part 135 helicopter operations (FAR 135.205(b)), the prohibition on aerobatic flight (FAR 91.303(c)), the prohibition on ultralight aircraft operations without prior authorization (FAR 103.17), the prohibition on Small Unmanned Aircraft operations without prior authorization (FAR 107.41), and more.