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Source describing what determines class D reverting to class E or G when tower closes?

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Airspace, General Aviation

I've hit kind of a roadblock in finding an official source for this one.  When a class D tower closes, the airspace reverts to class E if weather reporting is available, or class G if it is not.  The only place I've found this in print is in the AOPA publication "Airspace For Everyone" where it states:

"When the tower is not operating but weather information is available, the airspace reverts to surface-based Class E (Figure 4) — that is, during periods of below-VFR weather, aircraft must be operating under IFR. If weather information is not available, the airspace reverts to Class G as shown in Figure 3."
However, I can't find this information specifying the weather reporting requirement anywhere else, whether in FAA publications or textbooks.  I've even checked FAA Order JO 7400.9Z for airspace designations and turned up nothing.  (I'm thorough...I even once went as far as finding a reference to a presidential order for something to do with warning areas.)  Sure, I can find plenty of references in text books and other sources that state that when a class D tower closes it becomes class E or class G, such as AIM 3-2-5 b 3 example 2:
"At those airports where the control tower does not operate 24 hours a day, the operating hours of the tower will be listed on the appropriate charts and in the A/FD. During the hours the tower is not in operation, the Class E surface area rules or a combination of Class E rules to 700 feet above ground level and Class G rules to the surface will become applicable. Check the A/FD for specifics."
...but nothing about the dependency on weather reporting.  I've searched the regs in part 71 and 91 and can turn up nothing.  And the A/F D legend describes what it means when it shows a class C or D tower closes and the airspace reverts to class E or G, but nothing about weather.  Various airports I checked show the airspace reverting to either E or G in their A/F D listing, but again nothing about the weather requirement.
The point of my long winded question is, can anyone point me to any other sources (preferably something from the FAA) in print or online that clearly state that the distinction between class D (or class C) airspace reverting to class E or class G when the tower closes depends on weather reporting capabilities?  (The reason I like to have definitive sources of obscure information is so that my aviation study documents have information based on know facts, not just random things I've picked up over the years from unknown sources.)

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5 Answers

  1. Best Answer


    Mark Kolber on Jan 26, 2016

    It’s really buried.

    It’s alluded to very briefly in the AIM discussion of Class D in 4-3-2:

    “Not all airports with an operating control tower will have Class D airspace. These airports do not have weather reporting which is a requirement for surface based controlled airspace….”

    The best FAA source is probably FAA Order 7400.2K – http://1.usa.gov/1RLvN4u. Even then you have to look at a few different paragraphs in the 350+ page document.

    Paragraph17-2-10 discusses the requirement for weather observation for Class D. 18-1-3 applies that requirement to Class E surface areas.

    But notice that the requirement isn’t just for weather. The Class E surface area must also have the 17-2-9 requirement for some way to contact ATC from the surface. If you look at the AFD entry for KFNL near Denver, for example, you will see there is a dedicated CD fraquency.

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  2. Skyfox on Jan 27, 2016

    Awesome! Thanks, Mark! I’ve never seen that FAA order before. It’s very informative and helpful.

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  3. Mark Kolber on Jan 28, 2016

    Skyfox, there’s a lot of those Orders floating around on various subjects. I only came across it some time ago because, like you, I saw many people state the result without pointing to the source. I got curious. It wasn’t easy to find 🙂

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  4. connor on Nov 05, 2016

    Now it is FAA order 7400_11A
    https://www.faa.gov/documentLibrary/media/Order/7400_11A.pdf

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  5. Skyfox on Nov 27, 2016

    JO 7400.11A is titled “Airspace Designations and Reporting Points” and deals with the specifications and definitions of every bit of airspace in the US
    .
    JO 7400.2K is titled “Procedures for Handling Airspace Matters” and has more to do with the procedures dealing with various types of airspace.

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