The uncontrolled airfield where I have my airplane gets foggy in the morning occasionally, but there have been times when there is just a little fog where the AWOS station sits so it reports 1/4 mile visibility and undetermined ceiling, yet the runway farthest from it is clear and there are no clouds. My flight instructor and ground school instructor said you must always comply with the AWOS reported conditions, yet my flight examiner (I just got my private pilot license) said a pilot can overrule the automated station if it is clearly wrong. Machines can break and are limited to where their position is. FAR 91.155 talks about visibility, but doesn't mention how it is determined. Flight visibility is determined by the pilot, so I interpret this to mean he can overrule the AWOS if it is clearly wrong.

(d) Except as provided in §91.157 of this part, no person may take off or land an aircraft, or enter the traffic pattern of an airport, under VFR, within the lateral boundaries of the surface areas of Class B, Class C, Class D, or Class E airspace designated for an airport—

(1) Unless ground visibility at that airport is at least 3 statute miles; or

(2) If ground visibility is not reported at that airport, unless flight visibility during landing or takeoff, or while operating in the traffic pattern is at least 3 statute miles.

(e) For the purpose of this section, an aircraft operating at the base altitude of a Class E airspace area is considered to be within the airspace directly below that area.

Another question about (e), after reading it about 5 times: my airport is class G up to 700 feet, then turns into class E above that. Does (e) mean that if I am at 700 feet AGL, I am still in class G? Of what significance is this?

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    $\begingroup$ if you do decide to takeoff, it's very much on your own risk. $\endgroup$ Commented Sep 27, 2014 at 15:03
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    $\begingroup$ Here's a suggestion: take a photo of the runway area just before you take off, so if there is an issue, you can show the photo to prove that the AWOS was wrong. $\endgroup$ Commented Mar 19, 2015 at 21:20
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    $\begingroup$ My suggestion -- buy the airport authority/owner a transmissometer for the far runway for Christmas :) (I'm sure you're not the only pilot who's run into this pickle, based on your description of it) $\endgroup$ Commented Aug 13, 2015 at 23:23

4 Answers 4


In the specific case that you mentioned (VFR at an uncontrolled field), you can take off or land because the only legal requirement is to maintain VFR cloud clearance and it's your responsibility at the pilot to do that. The possible downside would be that if you have some kind of accident or incident and the FAA or NTSB investigates, they will take the AWOS reports as the reference for weather conditions at the time. If weather or visibility was relevant to the accident then your decision might be questioned, unless of course there are witnesses who can confirm the actual conditions.

In the case of a controlled field and VFR, ATC will base their actions on the reported conditions so they would tell you that the field is IFR only. One 'workaround' that could be useful is an SVFR clearance, which allows you to operate VFR in an airport surface area even below VFR minimums. You have to request it because ATC can't offer it although they may hint strongly at it to help you out: "the field is IFR, is there anything you'd like to request?" But ATC may not issue an SVFR clearance if the reported visibility is below 1 mile, so in the scenario you mentioned it wouldn't help you. (And note that you need an instrument rating for SVFR at night.)

Under IFR the picture is different. A part 91 IFR flight can legally depart in zero visibility so there would be no issue there, provided that you get your clearance on the ground first, before entering IMC. Legal in this case obviously isn't the same thing as safe, though.

I deliberately didn't answer your second question because I think it would be best for you to submit it as a separate question.

  • $\begingroup$ You don't even need an IFR clearance to depart IFR if the airport is in uncontrolled (G) airspace. You just need a clearance before you enter controlled airspace. $\endgroup$
    – Khantahr
    Commented Sep 29, 2014 at 16:06
  • $\begingroup$ @Ralga, that's true in general but in the specific case where a class G airport is in IMC then you still need an IFR clearance because there's no way to fly there legally under VFR. $\endgroup$
    – Pondlife
    Commented Sep 29, 2014 at 16:35
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    $\begingroup$ No you don't. A class G airport is in class G airspace, it is not simply an uncontrolled airport in class E airspace as many are. There are many areas where class G goes up to 14,500 MSL, so you could easily take off IMC, fly somewhere IMC, and land IMC (though I don't know of any published approaches in class G) without ever talking to anyone and be completely legal. $\endgroup$
    – Khantahr
    Commented Sep 29, 2014 at 17:00
  • 1
    $\begingroup$ @Ralgha Good point, and I admit I hadn't considered/phrased it properly: I wasn't distinguishing an IFR clearance from an IFR flight. Entering cloud in class G on an IFR flight without an IFR clearance is indeed legal, if you can maintain the minimum IFR obstacle clearance. $\endgroup$
    – Pondlife
    Commented Sep 29, 2014 at 19:58
  • $\begingroup$ OK, so fog being a ground based cloud, then as long as I am clear of the fog/cloud and can see for at least 1 mile in G airspace, I should be legal. Another suggestion would be take a few pictures before departure to prove the visibility was sufficient. $\endgroup$
    – Eric
    Commented Oct 1, 2014 at 10:59

According to AIM 5-5-1 paragraph b:

The pilot-in-command of an aircraft is directly responsible for, and is the final authority as to the safe operation of that aircraft.

CFR Section 91.3(a) states:

The pilot-in-command of an aircraft is directly responsible for, and is the final authority as to, the operation of that aircraft.

You'll see this pattern throughout the FAR/AIM's. The regulations state what parameters you can operate under, but you're responsible for gathering data from METAR's, TAF's, ASOS and ATIS and other sources and making a decision on weather you are able to comply with VFR weather minima for the class of airspace you're in if you depart.

Regarding your second question: The floor of E is at 700ft so that means if your altitude is 700ft AGL exactly you're still in E but you're subject to the weather minimums of whatever is below it which in your case is class G weather minimums. If the floor of the class E was on top of Bravo airspace, then if you're exactly on the floor you're subject to class B weather minimums. I think it's just anticipating the lawsuit that may arise from someone being exactly at 700ft and claiming they were in class E instead of whatever is below it with regards to weather minimums.


Read 91.157: (d) "The determination of visibility by a pilot in accordance with paragraph (c)(2) of this section is not an official weather report or an official ground visibility report."

Even though this is in 157 not 155, I think that if you were involved in a weather-related incident, the FAA would argue that the OFFICIAL reported weather controls, not the pilots judgment. This is probably what the Instructor means.

However, many uncontrolled fields, such as yours, have non-official automated reporting, which you could argue is advisory and not regulatory. This is probably what the Examiner means.


A couple of points that may not have been adequately covered yet--

Your question mentions FAR 91.155(d). But in your example, you are not "within the lateral boundaries of the surface areas of... Class E airspace designated for an airport". The airspace described by that phrase is the airspace within dashed magenta lines, where Class E airspace comes all the way down the surface. (See for example KSHR-- link to sectional chart.) So FAR 91.155(d) has no bearing on your situation. You only need 1 mile of flight visibility for daylight operations (and even for some night-time pattern work) so long as you don't climb up into the Class E airspace beginning at 700' AGL. And even if you climbed up into the Class E airspace, where you would need 3 miles of flight visibility, that would have nothing to do with FAR 91.155(d), which would still have no bearing on your situation.

Also, since you are not "within the lateral boundaries of the surface areas of... Class E airspace designated for an airport", you cannot get a Special VFR Clearance for operations at and and near your airport, regardless of altitude.


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