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4 Answers

OROCAs for direct random RNAV routes

Asked by: 4554 views , , ,
Airspace, Instrument Rating, Student Pilot

"OROCAs depicted on NACO en route charts do not provide you with an acceptable altitude for terrain and obstruction clearance for the purposes of off-route, random RNAV direct flights in either controlled or uncontrolled airspace. OACRAs are not subject to the same scrutiny as MEAs, MVAs, MOCAs, and other minimum IFR altitdues." (Instrument Flying Handbook 3-28)

So, if OROCAs are not good enough altitudes to fly for obstacle clearance when flying random RNAV direct flights, then what is?

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4 Answers



  1. Kris Kortokrax on Mar 08, 2015

    There is no page 3-28 in the current version of the Instrument Flying Handbook (FAA-H-8083-15B) published in 2012.

    The Pilot Controller glossary defines OROCA as:

    “An off-route altitude which provides obstruction clearance with a 1,000 foot buffer in nonmountainous terrain areas and a 2,000 foot buffer in designated mountainous areas within the United States. This altitude may not provide signal coverage from ground-based navigational aids, air traffic control radar, or communications coverage.”

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  2. Drew on Mar 11, 2015

    Sorry, I meant 2-27 of the Instrument Procedures Handbook. Here’s the portion:

    “OROCAs are intended primarily as a pilot tool for emergencies and SA. OROCAs
    depicted on en route charts do not provide the pilot with an acceptable altitude for terrain and obstruction clearance for the purposes of off-route, random RNAV direct flights in either controlled or uncontrolled airspace.”

    Am I understanding “off-route, random RNAV direct flights” as being unpublished RNAV routes between 2 fixes/navaids? The only word I’m confused about is the word “random”. Maybe that word is the key to understanding this? Or maybe the FAA is saying that trying to fly direct routes without a published RNAV MEA is not safe?

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  3. Drew on Mar 11, 2015

    Looking at figure 2-48, I can see what a random RNAV route looks like. But an OROCAs are supposed to cover quadrants of any area, so I don’t see how they can’t provide obstacle clearance for any flight.

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  4. Kris Kortokrax on Mar 11, 2015

    The only place I see anything resembling a definition of obstacle clearance requirements is in 91.177 (a)(2). OROCA provides this amount of clearance.

    The important thing to note is that this is the MINIMUM altitude. OROCA guarantees you obstruction clearance. MEA guarantees you obstruction clearance and navigation signal reception.

    Neither guarantees you radar coverage or communications capability.

    One of my earlier instrument students planned a cross country at the minimum altitude. I let the plan stand. During the flight, we reached a point where ATC instructed him to report the next compulsory reporting point. That was when he learned that higher is better.

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