Lets Talk About OROCA

luvflyin

luvflyin

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The FAA outright says not to use it for computing your minimum airway altitude in the Instrument Procedures Handbook. Your quoted information pretty much indicates why (collective wisdom that has been promulgated via other means over the years).

The sectional chart MEF figures make it a bit easier, provided you use them correctly. Of course they can be rather pessimistic if the determining obstruction is outside your actual 4 mile swath.
 
flyingron said:
The FAA outright says not to use it for computing your minimum airway altitude in the Instrument Procedures Handbook. Your quoted information pretty much indicates why (collective wisdom that has been promulgated via other means over the years).

The sectional chart MEF figures make it a bit easier, provided you use them correctly. Of course they can be rather pessimistic if the determining obstruction is outside your actual 4 mile swath.
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Yeah. They are proposing to not only doing away with that "don't use them to compute..." They are proposing making them mandatory. If I read it right, OROCAS would be added to MEA and MOCA as "minimum altitudes for IFR operations." For now, like you say, MEF's can be more valuable because they are half the size of OROCA grids. Ya just gotta remember that while OROCA's give you 1000 or 2000 feet of clearance depending on Mountainous area or not, MEF's only give you about 300.

EDIT: They aren't proposing making it a "hard" altitude. Someone did at one time but that got nixed
 
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I don't get that at all. It is saying that they should say the OROCA will meet the requirements of 91.177, but it doesn't say anything about requiring it for all off airway routes. You're still free to calculate your own with MEFs or whatever else you have at your disposal.
 
flyingron said:
I don't get that at all. It is saying that they should say the OROCA will meet the requirements of 91.177, but it doesn't say anything about requiring it for all off airway routes. You're still free to calculate your own with MEFs or whatever else you have at your disposal.
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I see that now. I was keying off on "The ACF Point-to-Point Subcommittee, established at ACF 16-02,discussed the RTCA proposed solution which was to replace OROCA with a Grid Minimum IFR Altitude (MIA)." Looks like that got nixed.
 
Here in the west I'd sort of like to see Enroute charts with something like the controller MVA/MIA chart/contours instead of a pure grid. With a 60NM grid you get things like 16,000+ OROCA NW of Denver and on-airway MEA of 11,000 in some areas. Of course we can switch to a VFR chart to check terrain, but it would be nice to see what ATC can actually give you if you need to be off-airway.
 
Having MVA on the enroute chart would really clutter it up and is probably impractical. . Depending on the airspace those MVA charts have numerous sectors, all with possible different altitudes. Think you could pull up the MVA as a map on the scope back when I did ATC, but that's been many moons ago.
 
However, the impact of off-cycle obstructions is currently not known because OROCA is not part of the OE/AAA process. Incorporating OROCA into the OE/AAA process is fundamental to improving this product and providing pilots the assurance they need that they are complying with FAR 91.177.
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This certainly caught me by surprise.

There is no method available to a pilot today to use FAA products and determine they meet FAR 91.177 compliance should they fly off-route because no notice is provided to the pilot of a temporary obstruction. The subcommittee does not desire each temporary obstruction to warrant the issuance of a NOTAM as we believe a single NOTAM, at most, for each OROCA grid value would efficiently resolve this issue and communicate to pilots their FAR 91.177 compliance altitude. The lack of a NOTAM for temporary obstructions impacts the Maximum Elevation Figure (MEF) provided on Sectional charts and other charting products and mechanisms.
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Yikes.
 
The OROCA is useful and better than the MEF on a Sectional, since the OROCA includes the additional 1000-2000 ft. altitude in mountainous or non-mountainous terrain and are updated every 28 days instead of every 6 months. The cruise altitudes are the IFR altitudes at or above the OROCA for direction of travel. In the clip below, near Smithfield, NC (KJNX) if going your MEA would be 4000 and 5000 going westerly and easterly respectively. I've never been aware of any temporary obstructions that would encroach on these altitudes. Generally, temporary obstructions rise only a few hundred feet above the ground, certainly not a thousand feet or more. If you follow OROCA guidance on the charts for cruise, I can't foresee of a scenaro where you'll smack into anything.
 
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