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I'm looking at the differences between Class E and Class G (AIM 3-2-6) airspace in the United States and I get that there are different flight condition requirements depending on AGL/MSL altitudes, but if you're outside a Mode C veil and around an untowered airport (So you don't need a transponder, don't need a radio), why not make everything Class E?

I think the answer came to me while writing this out...is it this simple?

Does Class G exist because for whatever reason (Radar services not available, technical reasons, etc.) ATC is unable to provide IFR separation services in that area, so it has to be deemed "uncontrolled?"

Is there some other reason why Class G exists besides being a catch-all?

Class G airspace (uncontrolled) is that portion of airspace that has not been designated as Class A, Class B, Class C, Class D, or Class E airspace.

Like is there some benefit that you get when you're in Class G instead of Class E? The only thing I could think of is that the flight visibility is less than 3 miles but more than 1, it's daytime and the cloud deck is lower than 500 feet AGL (since you just need to be clear of clouds and 1 SM visibility), you could take off VFR in Class G and you couldn't take off in Class E. (However, you'd still have to be sure not to be engaged in Careless or reckless operation (14 CFR § 91.13).)

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  • $\begingroup$ Are you asking for FAA only? Cause in EASA, it's really just there to allow VFR traffic to fly in not-so-nice weather... $\endgroup$ – SentryRaven Sep 7 '16 at 6:52
  • $\begingroup$ I'm asking FAA/United States only. $\endgroup$ – Canuk Sep 7 '16 at 6:53
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    $\begingroup$ My designated pilot examiner explained it to me like this: "When the government decided to take over all the airspace, they left a couple pieces for the guys complaining about "the man" being in their hobby, so they said "here's a piece, and here's a piece, etc" to appease those people". $\endgroup$ – Ron Beyer Sep 7 '16 at 14:21
  • $\begingroup$ It's so Superman can fly around at low altitude without having to carry an airband radio. $\endgroup$ – Sean Feb 10 at 4:17
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You can also fly Ifr without a clearance in G.

Remember that the entire purpose of airspace is to keep us from hitting airliners. It is not about keeping GA planes apart. When you look at wx mins that is clear. The FAA gives us the freedom to fly around in low vis so long as we stay out of the areas you'd find airliners.

-Robert CFII

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Class D and above require good weather, and permission, to enter.
Class E airspace requires good weather only.
Class G airspace requires not much. That's the benefit/difference of Class G.

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  • $\begingroup$ Class A also requires an IFR flightplan to enter. $\endgroup$ – Sean Feb 10 at 4:18
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Airspace classifications above G exist to protect commerce. (The FAA exists to protect commerce.) That is primarily IFR operations, as well as carriers and others that utilize ATC services. The protections include around congested airports (towers, radar service areas) and airspace for route structures.

Just 50 years ago, there was much more uncontrolled airspace in CONUS. Air routes (Victor airways) were protected, and airspace moved to higher classification levels, and along with it NAVAID facilities were implemented, better radio coverage for FSS and ATC, as well as more terminal and enroute radar service areas.

FAA Order JO 7400.11B is an example of the FAA issuing orders classifying airspace for the purpose of serving airports and their instrument approaches. Other airspace, such as Class A was defined by broad regulation.

When I was first instrument rated, it was possible to make substantial trips IFR, without a requirement to file flight plans. The airspace was uncontrolled, and little or no ATC services were available. Flight plans could be filed for search and rescue, but separation services were not available. FSS stations and their remotes (RCO) were a primary link for IFR operations in uncontrolled (now Class G) airspace.

It is noteworthy that radar coverage is not necessary for airspace to be classified as controlled airspace. Rather there is the need to be able to control that airspace to assure the separation and provide weather services for aircraft. It is true that some airspace, for example, Class C, is defined by the existence of radar services. If radar goes down, then class C reverts to Class D and class E. But in general the classification of airspace is done to support the operations and the services rendered in that airspace.

https://www.faa.gov/air_traffic/nas/nynjphl_redesign/documentation/feis/media/Appendix_A-National_Airspace_System_Overview.pdf

https://www.faa.gov/documentLibrary/media/Order/JO_7400.11B.pdf

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All airspace was originally uncontrolled. Then planes started crashing into each other, especially in bad weather, and someone got the bright idea of having controllers to track where planes were and keep them separated. Yay!

Those controllers expect to be paid and need radar/radio equipment, though, so it was only done where there was enough danger to justify that expense, e.g. around busy airfields. As planes got faster, a low-altitude speed limit was added so that new danger was limited to high altitudes, which are cheaper to control due to physics. But traffic kept growing, so they kept adding more and more radar/radio coverage to enable control at lower and lower altitudes.

There's still a limit to budgets, though, so most of the last bit near the ground remains uncontrolled--now called class G. In some countries, it's actually a rather large part of the lower airspace because they simply haven't thrown as much money at radar/radio coverage as others have, and that's often (but not always) linked to lower traffic density and correspondingly lower collision risk.

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