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Asked by: 1260 views Airspace

I have notice on charts big blue numbers scattered around.

Are these numbers the altitude of the highest obstruction in the area or the highest ground in the area? 

What area is covered?

I see no mention in the chart legend.

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3 Answers

  1. Kris Kortokrax on Feb 11, 2016

    When I open up my Chicago secitonal, I see a box following the list of MOAs. It states that “This char contains Maximum Elevation Figures (MEF).”

    It further states that it is based on the highest known feature in each quadrangle.

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  2. Best Answer

    Skyfox on Feb 11, 2016

    While it should be somewhere on the chart (not necessarily in the chart legend), you can always check out page 7 of the Aeronautical Chart User’s Guide [ https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/media/Chart_Users_Guide_12thEd.pdf ]

    That gives a full description of the MEF (maximum elevation figure) on VFR charts and how it’s calculated. There is a separate MEF for every quadrangle on the chart, which is a square of half an degree of latitude and longitude. Similarly, IFR charts have the OROCA (off-route obstacle clearance altitude) which serves roughly the same purpose except for having greater obstacle clearance margins for IFR aircraft, and that’s described on page 56 of the same chart guide as well as on the IFR charts themselves.

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  3. jmr3rd on Feb 11, 2016

    Thank you skyfox
    Exactly what I wanted

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