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6 Answers

Additional Control Area Limit

Asked by: 3478 views Instrument Rating

On the low IFR chart, what's the function of the brown "additional control area limit"? I see often this brown circling some airports on the chart but cannot identify its purpose. At first I thought it signified the E airspace but it doesn't look like it given that many airports surrounded by E airspace on the VFR chart do not have the circle line on the low IFR chart.

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6 Answers



  1. Mark Kolber on Feb 03, 2017

    Sometimes it helps to mention an airport where you have seen it on the off-chance that looking at it might give a clue.

    When the FAA reclassified airspace into today’s alphabet soup in the early 90’s there were some areas that didn’t quite fit. Offshore control areas were one and were designate by the names Control ###. Take a look at this chart snippet. Is this what you are referring to?
    https://skyvector.com/?ll=44.53812173661153,-124.14083862509926&chart=302&zoom=2&fpl=JAMIE%203750N07549W

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  2. Lemontree on Feb 03, 2017

    I’m sorry Mark. I wanted to include the picture or the link, but I didn’t know how to do it and I still don’t know.The one I had in mind was “Bowman Regional(BWW).” If you type the three letter and click on the “go” button in Skyvector, you’ll see it. Not just that airport. Many airports around it have the brown circle surrounding them.

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  3. Best Answer


    EAD on Feb 03, 2017

    If you notice, the BWW airport underlies the MOA. In this case the Powder River 3 Low MOA starts at 500 AGL EXCEPT for the area within the brown circle, where it starts at 2000 AGL.

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  4. Lemontree on Feb 04, 2017

    That was why!. Thank you EAD>

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  5. Mark Kolber on Feb 04, 2017

    Isn’t that a magenta circle? Either way, see how easy it is with a chart reference? A solid circle with some text pointing to it. The text usually tells you exactly what it is.

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  6. Russ Roslewski on Feb 05, 2017

    Mark he’s looking at the Low Enroute chart, where it looks brown to me (versus magenta on the VFR sectional).

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