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I came across the following question when prepping for my PPL written exam:

"During operations outside controlled airspace at altitudes of more than 1,200 feet AGL, but less than 10,000 feet MSL, the minimum flight visibility for daytime VFR flight is: "

And the choices were a) 1 SM b) 3 SM c) 5 SM.

I know that B,C,D,E are controlled and G is uncontrolled. But I thought that "outside controlled airspace" just meant we are not in the vicinity of an airport especially since they mention more than 1200ft AGL. Versus we are in class G airspace.

Class E typically exists everywhere from 1200ft AGL up to 18000ft MSL. Everything below that 1200ft AGL mark is class G. I am aware of cases like 700ft AGL or some other height AGL if specified, but I'm ignoring those for the purpose of this question.

I figured since the question makes the effort to say more 1200ft AGL, this probably means that we're operating in class E airspace (despite saying "outside controlled") away from an airport. Hence, I picked B) 3 SM.

But the right answer was 1 SM. The explanation was that outside controlled airspace meant class G.

What did I misunderstand? How should I have reconciled the two bits of information: outside controlled airspace and more than 1200 ft AGL?

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  • $\begingroup$ What has four legs, a pillow and a brick? A bed - the brick is there to make it harder. $\endgroup$
    – Frog
    Dec 30, 2021 at 9:06
  • $\begingroup$ In other words, the answer to the question is easy but the question is designed to make you doubt yourself. $\endgroup$
    – Frog
    Dec 30, 2021 at 9:07
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    $\begingroup$ That’s Class G airspace and at night it’s 3 statute miles visibility and in the day 1 sm visibility. § 91.155 Basic VFR weather minimums. $\endgroup$
    – JScarry
    Dec 30, 2021 at 15:45
  • $\begingroup$ @JScarry -- guess I missed the obvious; you are right of course $\endgroup$ Dec 30, 2021 at 16:01
  • $\begingroup$ Can we assume that you are not flying a helicopter? $\endgroup$ Dec 30, 2021 at 16:51

1 Answer 1

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This answer will assume from the context of the question, that the question pertains to the airspace of the United States. This answer will also assume that the question pertains to airplanes, or other aircraft that are not helicopters. Note that the answer would be different for helicopters.

The test question was:

During operations outside controlled airspace at altitudes of more than 1,200 feet AGL, but less than 10,000 feet MSL, the minimum flight visibility for daytime VFR flight is:

The correct answer is "1 statute mile". You are flying in uncontrolled airspace-- meaning Class G airspace-- in the daytime. See FAR 91.155- Basic VFR weather minimums.

What does "outside controlled airspace above 1200ft AGL" mean?

"Outside controlled airspace" means "in uncontrolled airspace", which means "in Class G airspace". You seem to doubt that any Class G airspace exists above 1200' AGL, but it does.

Controlled airspace with a floor at 1200' AGL only exists where it is needed to protect specific airways, instrument approaches and departures, etc. Now, it so happens that over time, this has led to very few places remaining in the lower 48 states where controlled airspace has a floor higher than 1200' AGL, but a few such places do still exist. See for example this related ASE question: What are concrete examples for class G up to 14500?. And Alaska, such airspace is more common-- See for example this related ASE question: What is the purpose of this interesting pattern of class E airspace in northwest Alaska?

If you are wondering-- "Why is it so complicated? Why bother to have those few little slivers of Class G airspace with that extend higher than 1200' AGL? And why have two phrases -- 'uncontrolled airspace' and 'Class G airspace'-- with the same meaning?" Well, it's a situation that has slowly evolved over time. If you had a "magic map" that could scroll back through time, and you slowly scrolled back through the last seventy years or so, you'd see more and more areas where the low-level airspace was "uncontrolled", until eventually the only low-level "controlled" airspace would be small, mostly circular, shapes around some airports, plus a network of airways. You'd also notice that prior to 1993, the "alphabet" naming system did not exist.

If you want to get more insight into the vast collection of different individual pieces of Class E controlled airspace with floors at 700' or 1200' AGL, that now have multiplied to cover nearly the entire country, view the FAA's "Airspace Designations and Reporting Points" document, current edition JO 7400.11F. Section 6005, starting on page E-224 and running through page E-989, lists the "E5" Class E airspace areas which normally have floors at 700' AGL, and section 6006, running from page E-990 through E-1008, lists the "E6" Class E airspace areas which normally have floors at 1200' AGL. Sections 6009 through 6011, running from pages E-1018 through E-1164, list the Federal Airways and Area Navigation Routes, which normally have Class E floors at 1200' AGL. Note the large range of different dates as to when the airspaces were created or last amended. So that's 175 pages to describe the Class E airspaces with floors at 1200' AGL. Yes, it certainly would take many fewer pages, if the document simply specified that "Class E Controlled airspace always begins at 1200' AGL or lower, except in these specified areas", and then listed the few remaining "hold-outs" that have managed to "slip through the cracks"!

But I thought that "outside controlled airspace" just meant we are not in the vicinity of an airport

That is not correct.

You seem to have some confusion around how the concept of "controlled airspace" relates to towered airports. You should not use "controlled airspace" as a synonym for "the airspace around an airport with a control tower". They are not the same at all. Also, be aware of the ambiguity around the phrase "controlled airport". The phrase "controlled airport" most properly means "an airport with surface-level controlled airspace", not "an airport with a control tower". It is often used otherwise, but this is arguably incorrect. Due to this ambiguity, it's a good practice to avoid using the phrase "controlled airport" altogether.

Again, it is informative to look back through history. Originally, the phrase "control airport" or "controlled airport" was used to describe airports surrounded by "control zones", where higher cloud clearance and visibility requirements were imposed on VFR pilots (or "contact" pilots, to use the old term) to protect IFR (instrument) traffic. These "control zones" have evolved into today's surface-level Class E airspaces, Class D airspaces, etc. But there never was a direct correlation between airports listed as "controlled airports", and towered airports, where VFR pilots were required to get clearances, or establish communications, before entry. Many "controlled airports" had no control towers. And a few towered airports had no "control zones" and therefore did not appear on the list of "controlled airports", yet VFR pilots were required to establish communications with the tower before entering the "Airport Traffic Area" around the airport. That's why the most correct meaning of the term "controlled airport" is still "an airport with surface-level controlled airspace".

Although the test question doesn't mention airports, this ambiguity around the phrase "controlled airport" may have contributed to your confusion.

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    $\begingroup$ Some CFIs incorrectly teach that class E is “uncontrolled” because VFR pilots do not need a clearance, which isn’t corrected until the student gets to IFR training. This question’s wording appears targeted at that error. $\endgroup$
    – StephenS
    Dec 30, 2021 at 12:58
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    $\begingroup$ I wish I could +1 multiple times, in particular for mentioning that "controlled/uncontrolled" and "towered/non-towered" are not synonymous! Not sure how 7–1–1 comes into it though—did you mean 7–5–1a2? $\endgroup$
    – randomhead
    Dec 30, 2021 at 17:24
  • $\begingroup$ @quietflyer I made a slight edit to my question. I mistyped the question. The original question said day VFR flight. Hence, I picked 3 SM thinking it was class E. But the right answer was 1 SM because it was class G during daytime. Nonetheless, the points in your question address my main confusion of "uncontrolled over 1200 AGL" $\endgroup$
    – Jonathan
    Dec 30, 2021 at 19:30
  • $\begingroup$ @Jonathan -- got it-- normally questions aren't supposed to be changed in a way that invalidates an existing answer, but I don't think anyone minds this time. I'll edit my answer when I get a chance. $\endgroup$ Dec 30, 2021 at 21:17
  • $\begingroup$ I have a similar question and i'd love to get your wide expertise on that question as well. aviation.stackexchange.com/questions/91022/… $\endgroup$
    – Jonathan
    Dec 30, 2021 at 22:01

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