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CFR 91.157 says that special VFR operations may be conducted below 10,000 ft MSL "within the airspace contained by the upward extension of the lateral boundaries of the controlled airspace designated to the surface for an airport". Does the "controlled airspace designated to the surface" refer to only the center cylinder of the class B or C upside down wedding cake? Or is the language saying referring to all class B and C airspace in addition to the airspace between the surface and class B and C shelves? Thank you

Steve V.
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Terry
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  • We have several related questions but I am unable to find any that specifically focus on whether the Class B or C "shelves" (and also the airspace directly above or below the "shelves") are meant to be included by the relevant language in the FAR. Peripherally related questions include https://aviation.stackexchange.com/questions/35297/which-parts-of-class-e-airspace-can-an-ultralight-part-103-fly-in-without-prio and https://aviation.stackexchange.com/questions/35407/may-aerobatics-be-performed-over-a-controlled-airport-without-getting-a-waiver . – quiet flyer Apr 13 '23 at 03:07

2 Answers2

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First question: yes. The controlled airspace designated to the surface for an airport is the center core of class B and C airspace, class D airspace, and class E airspace all the way to the surface (innermost heavy blue, innermost heavy magenta, dashed blue, and dashed magenta lines on the VFR charts.) This airspace, as well as any airspace directly above this airspace, is eligible for SVFR authorization, up to 10,000 ft MSL. The other shelves are excluded from SVFR authorization - the normal airspace rules apply to those regions. Moreover, if the center core extends above 10,000 ft MSL, that part of the center core that is above 10,000 ft MSL is also excluded.

quiet flyer
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FencerPTS
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    There is a ruling from the Office of the Chief Counsel that addressed this; this answer would benefit from citing that. Here it is: https://www.faa.gov/sites/faa.gov/files/faa_migrate/interps/2006/Hucker_2006_Legal_Interpretation.pdf . Note that it reverses an earlier ruling that said airspace in the "shelves" was considered to be "within the lateral boundaries" of controlled airspace designated to the surface. – quiet flyer Apr 12 '23 at 22:52
  • Actually though this answer could use some clarification. Because the outer shelves are also depicted as heavy blue and heavy magenta lines on the VFR charts! – quiet flyer Apr 12 '23 at 22:56
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    Just noticed something here-- note that the way the FAR is written, any airspace "within the lateral boundaries" of the controlled-to-surface portion (i.e. the inner core) of the Class B or C is eligible for Special VFR up to 10,000' MSL. It makes no difference how high the actual ceiling of the Class B or C is. If the ceiling is say 5000' MSL, or if the ceiling is 15,000' MSL, either way, makes no difference, all airspace above that inner surface footprint all the way up to 10,000' MSL would be eligible for SVFR. This answer implies otherwise. – quiet flyer Apr 13 '23 at 02:02
  • The point becomes especially relevant in the case of Class D airspace, where the ceiling of the airspace is typically relatively low- or for surface-level Class E airspace- which is another kind of airspace where SVFR is allowed "within the lateral boundaries of"- keeping in mind that you won't find a specific ceiling listed for the surface-level Class E airspace on the sectional chart. Also highly relevant to related question http://aviation.stackexchange.com/questions/35297/… -- the airspace above surface-level Class E airspace is off-limits to ultralights with no upper boundary. – quiet flyer Apr 13 '23 at 02:31
  • @quietflyer if the airspace does not extend beyond 10,000 ft MSL, SVFR cannot be requested by the pilot of the airport since the airspace is not under the control of the airport. As I understand SVFR, it is requested when the pilot advises that basic VFR cannot be maintained when entering into or transitioning through the surface area (typically the inner core) of the airspace. Consequently, the implicit limit of SVFR is the uppermost limit of the airspace but never beyond 10,000 ft MSL. For more info, see JO 7110.65Z 7-5-1 – FencerPTS Apr 13 '23 at 04:10
  • re "if the airspace does not extend beyond 10,000 ft MSL, SVFR cannot be requested by the pilot of the airpirt since the airspace is not under the control of the airport. " -- well, the pilot can certainly request! As to whether the request could be granted in real life-- we have several current or former ATC folks on this site who might be able to speak to that. Could be fertile ground for a good new ASE question. My comment was only meant to address the actual wording of the FAR, not what could be granted in actual practice. Wouldn't be the first time that the two are not aligned! – quiet flyer Apr 13 '23 at 04:13
  • I think you actually meant to address the status of airspace that is below 10000' MSL but above the ceiling of the Class D, C, or B airspace. Right? But my same basic point applies. As I understand it, the actual letter of the FAR says that aircraft in that airspace are eligible for SVFR. It may be the case that ATC would always decline SVFR for any airspace above the ceiling of the Class D, C, or B, but I don't see that that is written into the FAR. Again, seems like a good basis for a new ASE question. – quiet flyer Apr 13 '23 at 04:19
  • Link to the document you mentioned-- https://www.faa.gov/air_traffic/publications/atpubs/atc_html/chap7_section_5.html -- I'm not seeing any specific statement in section 7-5-1 indicating that SVFR can not be authorized in airspace above the ceiling of (but still within the lateral boundaries of, i.e. above the surface footprint of) the Class B, C, or D "surface area" (inner core) airspace in question. – quiet flyer Apr 13 '23 at 04:34
  • I think I've just convinced myself the other way. Approach control can issue SVFR through FSS for non-towered Class E airports. As such they would be able to grant the clearance up to 10,000 ft and above the ceiling of the tower-controlled airspace (typically class C and D since class B is typically up to 10,000 ft MSL anyway). So, cannot request if from airport, but can request it from Approach (by way of FSS if necessary). – FencerPTS Apr 13 '23 at 04:38
  • Re your comment https://aviation.stackexchange.com/questions/98636/which-portions-of-class-b-and-c-airspace-does-cfr-91-157-special-vfr-apply-to/98640#comment274551_98640 -- it's been several days now so I took the liberty of modifying your answer to reflect this. Feel free to undo any portion of the edit that you don't agree with. – quiet flyer Apr 15 '23 at 14:06
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With respect to your question, "controlled airspace designated to the surface" applies only within the airspace contained by the "...upward extension of the lateral boundaries of the controlled airspace designated to the surface for an airport." (see 14 CFR Part 91.157 Special VFR weather minimums.)

(highlight is mine)

So, for an airport at "0" feet MSL (for example), if there is a Class B shelf, the base of which starts at 7000 feet MSL, then that shelf would be outside of the "upward extension of the lateral boundaries of the controlled airspace designated to the surface..." and Special VFR would not be authorized.

This FAA Interpretation, located by @quietflyer, may be helpful in understanding Class B and Class C surface areas and shelves.