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3 Answers

no obstacle’s penetrating the 152 feet per nm obstacle slope

Asked by: 1517 views Instrument Rating

When FAA evaluates an airport for the need to have an obstacle departure procedure based on terrain, i understand that if there is no obstacle's penetrating the 152 feet per nm obstacle slope, then FAA will not designate a departure procedure. How far out in terms of miles away does FAA evaluate  the terraine for this obstacle slope? Do they evaluate out to 10 miles, 30 miles, 50 miles?    The reason for this question is if i do not see any published departure procedure for an airport, do i assume that there is no obstacle's penetrating this 152 fpnm obstacle slope gradient infinately?    It seems to be a bad assumption but i'm not sure.

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3 Answers



  1. Gary Moore on Dec 03, 2018

    This may help….

    https://www.faa.gov/regulations_policies/orders_notices/index.cfm/go/document.information/documentID/1032731

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  2. Russ Roslewski on Dec 03, 2018

    While I am usually of the opinion that it’s better to show someone how to find the answer than to just given it to them, I do think the 8260.3D, TERPS, is more than a little hard to digest for anyone not in the TERPS business.

    The answer is a 25 nm radius from the airport for non-mountainous areas, and 46 nm for mountainous areas (as defined in the FARs).

    Source – 8260.3D, para 14-2-1.

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  3. Gary Moore on Dec 04, 2018

    Fair point Russ – it was one of the required texts at Florida Tech decades ago when I was in school – perhaps – I\’m probably a bit overly proud that I even know about it 🙂 It is a tad esoteric…..

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