Class G Takeoff Weather Minimum Confusion

Discussion in 'Pilot Training' started by John Richardson, Oct 6, 2021.

  1. John Richardson

    John Richardson Pre-Flight

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    I'm confused about something. Let's say it's daytime and you are in a class G airport where the overlying airspace is class E, dropping down to 700' AGL (Inside the Fuzzy Magenta Circle). If the visibility is 1SM, you can legally take off in the class G airspace. BUT...as soon as you reach 700' AGL, you are in class E which requires 3SM of visibility.

    So, am I to understand that at 699' AGL I'm legal, but if I climb one foot of altitude, I'm now illegal? To avoid this am I supposed to fly around at no more than 699 feet AGL? You can't even achieve pattern altitude this way. What would be the point of taking off at the class G airport?

    I missed a question on the written exam for this scenario where the correct minimum viz for takeoff was indeed 1SM. I answered with 3SM because it seemed like the logical/practical choice.

    Am I overthinking this?
     
  2. flyingron

    flyingron Touchdown! Greaser! PoA Supporter

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    There's nothing magic about pattern altitudes as far as the regs are concerned. You could bop around at 500AGL at your peril if the weather is less than 3SM. However, I strongly suggest you should see what visibilities of less than 3 miles actually look like. A mile would mean that you can't see the other end of the pattern at most places.

    As far as the reg goes, you can take off with 1SM, but you better have a plan as to what to do when you hit controlled airspace. Note that the visibilities and cloud clearances aren't set for the VFR pilot's convenience or safety, they're set there to protect controlled IFR operations.
     
  3. rhkennerly

    rhkennerly Pre-takeoff checklist

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    I see the word problem, but I'm hard-pressed to see it as a practical issue, since the 152 cloud clearance rule still applies to both the 1SM & the 3SM visibility limit. Essentially, you are describing extremely marginal VFR conditions, if not actual IFR.

    It took me a long time to realize that all of the Airspace Class weather limits really have one purpose: keeping instrument approaches clear during actual IMC conditions.

    Since I've taken my last FAA written exam or flight test, all I need to know is that my personal VFR weather limit is:
    • 5SM vis,
    • never on top of a layer I can't see the edge of,
    • at least 1000 ft above the ground with an additional 500 ft cloud clearance above me (in other words a cloud deck at 1500 ft MSL or more) and
    • at least 2k away from clouds.
    Which makes all of those pretty colors on the sectional just that, pretty colors.
     
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  4. midwestpa24

    midwestpa24 En-Route

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    Another example of what is legal isn't always safe. Yes in your example of Class G airspace, you could legally takeoff with 1 mile vis as long as you avoided the overhead Class E airspace. Legal, but probably not smart.
     
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  5. TommyG

    TommyG Pattern Altitude

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    Yes that is exactly how it is. But if you are up doing pattern work with 1 SM you have some bigger things to worry about.
     
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  6. Pi1otguy

    Pi1otguy Pattern Altitude

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    You're thinking which is good. "Can I ..." vs "should i..." will be a recurring theme.

    If you want a mind bender, would you hypothetical flight be a 91.13 violation?
     
  7. Dana

    Dana En-Route

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    In coastal areas it's not unusual to take off under a low overcast or broken layer and fly into sunshine a few miles inland.
     
  8. Larry in TN

    Larry in TN Pattern Altitude

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    I've flown to airports where it was Class G airspace from the ground up to, but not including, FL245.

    There's a lot of World out there where the airspace is not the same as it is in central Ohio. There used to be a lot of that airspace in the CONUS but not so much anymore.
     
  9. MauleSkinner

    MauleSkinner Touchdown! Greaser!

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    Class G is perfectly good for enroute flying in much of the U.S., provided you are comfortable and competent flying in those conditions. But it takes a lot more effort to stay legal and safe at 600 feet than it does at 3000, especially when the visibility approaches 1-3 miles.
     
  10. Clip4

    Clip4 Final Approach

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    What if there was no ceiling, the ground visibility as >1 sm and the flight visibility at 500 AGL was >3 sm? In some parts of the US this happens.

    What if the ground visibility was unlimited and there was a 650 ft ceiling in an uninhabited part of Alaska?

    What if the weather has gone to crap on you and you need to get in to the airport?

    The obstacle clearance regs apply, but there are places in the US it can be done without an exceptional risk.
     
  11. luvflyin

    luvflyin Touchdown! Greaser! PoA Supporter

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    You did over think it. It was a test question. The answer to that question is 1 mile. Should you always depart when it is only 1 mile is another question.
     
  12. MauleSkinner

    MauleSkinner Touchdown! Greaser!

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    As one of the primary advocates of flying VFR in crappy weather, I’m not going to argue with this statement. :rolleyes:

    I am, however, going to note a possible drawback to the use of the word “need” in that sentence. Legal or otherwise, I think the “need” to get to an airport when the weather has gone to crap is overstating it. If the weather is getting below someone’s planned minimum, a precautionary landing should also be considered as an option.
     
  13. AA5Bman

    AA5Bman Line Up and Wait

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    Agreed - answered in the first post.

    Yeah, it's hard to imagine when you would take off in class G airspace at 1-3SM with overlying Class E. But as someone said, not every reg was written for your exact circumstance. I can think of a handful of times that a 700 OVC and less than 3SM might make sense - for instance, flying a 100mph floatplane over the sound where the whole world is a runway and you wouldn't have climbed much above 100' anyway.
     
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  14. brcase

    brcase Pattern Altitude

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    When you have the cloud layer at 700 feet agl extending 3 miles past the end of the runway then severe clear the rest of your route it can be useful. This is less an IFR question than a VFR question. It is on the IFR question set because as an IFR pilot you need to know what a VFR pilot can and may legally be doing as you pop out of the cloud at 700 feet.

    Brian
    CFIIG/ASEL
     
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  15. RussR

    RussR En-Route

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    I'd say that given the 91.119 minimum requirement to stay 500 feet away from any structures, the prevalance of cell phone towers and windmills that are greater than 100 ft tall, the undefined vagueness of "congested areas" requiring 1000 ft of clearance, and the ability to see all these things coming and adjust the route of flight with only 1 sm of visibility, makes your previous statement:

    rather unreasonable in anything but a helicopter, powered parachute, or weight-shift trike, which are not bound by 91.119.
     
  16. MauleSkinner

    MauleSkinner Touchdown! Greaser!

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    I would disagree, but for other reasons I won’t tell anyone they SHOULD do it.
     
  17. Dana

    Dana En-Route

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    It depends on where you are and how well you know the area. Going far, probably a bad idea, but for a short flight in familiar territory, like departing under a coastal layer as I mentioned above, or flying 10 miles to another familiar airport, not that big a deal.

    It also depends on the speed of the airplane... it's a lot safer in a Cub or other slow airplane than it would be, say, in a Bonanza.
     
  18. Palmpilot

    Palmpilot Touchdown! Greaser! PoA Supporter

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    This reminds me of a situation I encountered when departing from Port Angeles, WA a few summers ago. It wasn't quite the same situation, because the airport is in a class E surface area. Visibility was generally marginal due to widespread fires. When I was ready for takeoff, the AWOS, which had been reporting three-mile visibility, dropped to 2-1/2. The IFR departure procedure requires either an ADF or an IFR GPS, neither of which the airplane had. (It really bugs me when the owner of a rental plane removes the ADF without putting in an IFR GPS.)

    So I called Approach, received a special-VFR clearance, exited the surface area at 700 MSL, and stayed over the water at that altitude until the visibility improved enough to allow climbing into the overlying class E airspace. I was glad that the VFR GPS installed in the plane had a display with the red and yellow terrain warnings depicted, because there's plenty of it to warn about nearby!

    CLM area.png
     

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  19. Clip4

    Clip4 Final Approach

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    Sounds like a good plan in the flat lands,
     
  20. midlifeflyer

    midlifeflyer Touchdown! Greaser!

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    Years ago I happened upon the start of an instrument checkride oral. The first question was, "what are the weather minims to take off VFR from here?"

    it got a deer in the headlights look.
     
  21. MauleSkinner

    MauleSkinner Touchdown! Greaser!

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    “Plan” being a key word.
     
  22. Bill Watson

    Bill Watson En-Route

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    Flying around fog banks creates some interesting opportunities and risks. I was doing a daily early morning flight into a nearby airport for almost 6 months. An airport that tended to have a fog bank moving over it and around it many mornings. It also had a occasional IFR operation going though typically not at the break of dawn.

    It was not unusual for the numbers on one end to be in a fog bank and severe clear on the other end of the mile long runway. One could fly (a Maule) over the fog and land VFR, one could depart and turn before the fog. IFR traffic would typically have no idea of the exact airport conditions and could come in perfect VMC conditions or require a miss at DA due to the airport not being in sight.

    Flying a pattern in those conditions was rarely the issue. Lots of radio work and a swiveling head were key.


    Sent from my iPad using Tapatalk Pro
     
  23. dmspilot

    dmspilot En-Route

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    Yes, your knowledge of the FARs was being tested, not your decision making. Aside from the fact that it's legal to fly at 699' AGL in a non-congested area as others have noted, I will point out that VFR visibility requirements (except for controlled airspace surface areas) are flight visibility. Weather conditions could be such that the visibility is 1sm on the ground and >3sm at 700 feet.
     
  24. iamtheari

    iamtheari Administrator Management Council Member PoA Supporter

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    Lots of good information above. The VFR minimums are set to protect IFR planes from you, not to protect you from IMC. You should have personal minimums that are above 1 mile of visibility and clear of clouds. I would recommend a new private pilot have personal minimums of at least 5 miles of visibility in anything other than smoke, and 9 miles if there is smoke involved. (AWOS tends to report better visibility in smoke than really exists.)

    If you have a friend who flies IFR often, try to ride along for a trip in visibility between 1 and 3 miles sometime. It's spooky on a good day.

    As far as launching on a cross-country trip in class G airspace, remember that you'll eventually be in an area where class G goes up to 1200 AGL. So you don't have to stay at 600 AGL forever and you can legally fly over congested areas at 1000 AGL just fine. That can be a good idea. It usually isn't, though.

    These questions on the oral can transition into Special VFR, so make sure you understand when you can get SVFR, why you would want to, and how to make that decision safely for yourself.
     
  25. MauleSkinner

    MauleSkinner Touchdown! Greaser!

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    How to get one is a question that’s usually good for some blank stares. ;)
     
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  26. Palmpilot

    Palmpilot Touchdown! Greaser! PoA Supporter

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    Only if the structures in that area have zero height.
     
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  27. asicer

    asicer Final Approach PoA Supporter

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    They were during my PP oral, or at least my DPE declared them to be (prior to reaching my/his MVFR class D destination). ;)
     
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  28. iamtheari

    iamtheari Administrator Management Council Member PoA Supporter

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  29. pfarber

    pfarber Pre-takeoff checklist

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  30. Fearless Tower

    Fearless Tower Touchdown! Greaser!

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    Here is a slightly different question:

    Instrument rated pilot. Departing from an uncontrolled field in Class G.

    Ground fog over the runway - vis less than 1/4 mile, but the ground fog is only say 100' thick. Weather above the ground fog is CAVU.

    Can you legally take off?
     
  31. midlifeflyer

    midlifeflyer Touchdown! Greaser!

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    Departing IFR with an IFR clearance effective upon entering controlled airspace? Plain vanilla Part 91, yes you can legally take off. Takeoff minimums are only mandatory for " persons operating an aircraft under part 121, 125, 129, or 135 of this chapter." FAR 91.175(f). Smart and "careless/reckless" if you screw it up, are of course, are separate questions.

    Or, are you asking about departing with no clearance? I'd say also technically yes, although the FAA has frowned on the practice under 91.13 on the theory that you may be posing a danger to other IFR aircraft, for example, with an approach clearance into the airport or if the fog may not clear as you predict. I think that's a corollary to the loss of practical uncontrolled IFR in the lower 48.
     
    Last edited: Oct 16, 2021
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  32. Palmpilot

    Palmpilot Touchdown! Greaser! PoA Supporter

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    The height of the floor of class E airspace might enter into that one, since you would need to be 1,000 feet above the fog before you entered controlled airspace.
     
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  33. midlifeflyer

    midlifeflyer Touchdown! Greaser!

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    Good point!
     
  34. flyingron

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  35. iflyvfr

    iflyvfr Pattern Altitude

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    I was once doing TNGs at KLCK, Rickenbacker with a 12000' runway. Tower eventually had enough and told me to either land or go someplace else because he couldn't see me in the pattern. My instructor had recommended I try it in the 150 we were training in; it was good experience but not something I'd care to repeat in real life.