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I've noticed that when it comes to non-towered airports, some are in class G airspace and others have class E airspace starting from the surface. At first I thought the airports with class E at the surface might be in that configuration because they have precision approaches, but then I found exceptions where the airport has class G at the surface along with a precision approach. Is there a particular reason some non-towered airports are in class E while other are in class G?

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This answer is specific to the United States (heck, I don't know if this is an even an issue elsewhere in the world).

The airspace classification actually has nothing to do with whether or not a particular airport has a precision approach. It is based on two factors: communications capability and weather observations.

For a non-towered airport to have Class E (surface) airspace, ATC must have communications capability with aircraft down to the runway surface. Second, weather observations must be provided by a Federally certificated observer and/or Federally commissioned weather observing system. Reference: FAA JO 7400.2K, paragraphs 18-1-1 and 18-1-2.

If one (or both) of these conditions are not satisfied, the surface airspace will be class G with a class E floor of 700 ft. AGL if there is an instrument approach into the airport and 1200 ft. AGL if not.

Now, here's a twist: if the airport has a part-time control tower, the airspace may become Class G when the tower is closed, even if both communication and weather reporting requirements are satisfied. Be sure to check the Chart Supplement (fka A/FD).

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  • $\begingroup$ How can you confirm if a non-towered airport is E versus G? Does the FAA maintain a list? $\endgroup$ – Roger Oct 11 '16 at 14:00
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    $\begingroup$ This information is depicted on VFR charts. If you look in the chart legend, there is a notation that states 'Class E Airspace exists at 1200' AGL unless otherwise designated as shown above.' This means that an airport's airspace will be Class G unless there are graphics that indicate Class E starts at a lower altitude (i.e., 700' AGL or at the surface). $\endgroup$ – newmanth Oct 11 '16 at 14:50
  • $\begingroup$ Can you give a reference for your last point re: after control tower hours? AIM 3-2-5 says "when the control tower closes, the airspace revert back to either class E, or a combination of Class G and class E depending on the chart depiction and the description in the A/FD" but mentions nothing about weather observations. $\endgroup$ – David DeVine Sep 1 '17 at 22:13
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    $\begingroup$ @DavidDeVine, the last point was poorly worded as it is not a universal condition. I've updated it accordingly. Classification as controlled airspace (i.e. Class B, C, D, or E) is not automatic, thus an airport with a part-time control tower may (or may not) be controlled airspace when the tower is closed, even if the conditions for Class E surface area are met. $\endgroup$ – newmanth Sep 1 '17 at 23:48

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