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ORCA lower than MEA?



 
 
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  #1  
Old January 22nd 07, 06:51 AM posted to rec.aviation.ifr
Dan[_1_]
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Posts: 211
Default ORCA lower than MEA?

There are some places on IFR enroute charts where the OROCA (Off-route
obstruction clearance altitude) is actually lower than MEAs on an
airway in the same quadrant. The higher MEA is NOT due to obstacles in
adjacent quadrants.

If I'm on the airway, usually they don't let folks go down to the MOCA,
however if I file direct off-airways, how likely am I to be able to get
the ORCA? The goal is trying to stay below oxygen altitudes in
mountainous terrain while remaining IFR.

--Dan

  #2  
Old January 22nd 07, 02:20 PM posted to rec.aviation.ifr
Jim Macklin
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Posts: 2,070
Default ORCA lower than MEA?

MEA is established by VOR reception when distance or
obstacles require an altitude higher than terrain clearance
only requires. You may or may not be given a clearance, if
radar coverage is not available.

Buy or rent some oxygen equipment.



"Dan" wrote in message
ups.com...
| There are some places on IFR enroute charts where the
OROCA (Off-route
| obstruction clearance altitude) is actually lower than
MEAs on an
| airway in the same quadrant. The higher MEA is NOT due to
obstacles in
| adjacent quadrants.
|
| If I'm on the airway, usually they don't let folks go down
to the MOCA,
| however if I file direct off-airways, how likely am I to
be able to get
| the ORCA? The goal is trying to stay below oxygen
altitudes in
| mountainous terrain while remaining IFR.
|
| --Dan
|


  #3  
Old January 22nd 07, 02:38 PM posted to rec.aviation.ifr
Sam Spade
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Posts: 1,326
Default ORCA lower than MEA?

Dan wrote:

There are some places on IFR enroute charts where the OROCA (Off-route
obstruction clearance altitude) is actually lower than MEAs on an
airway in the same quadrant. The higher MEA is NOT due to obstacles in
adjacent quadrants.

If I'm on the airway, usually they don't let folks go down to the MOCA,
however if I file direct off-airways, how likely am I to be able to get
the ORCA? The goal is trying to stay below oxygen altitudes in
mountainous terrain while remaining IFR.

--Dan

When you go off-route the center will use is minimum instrument altitude
(MIA) chart. ATC will not use ORCAs; those are a concept that never
went anywhere other than to provide you with some information for
emergency or lost comm use.

Also, you can run into issues if you try to go direct through one of
those many chunks of Class G airspace in the western part of the country.
  #4  
Old January 22nd 07, 05:48 PM posted to rec.aviation.ifr
Ron Natalie
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Posts: 1,175
Default ORCA lower than MEA?

Dan wrote:
There are some places on IFR enroute charts where the OROCA (Off-route
obstruction clearance altitude) is actually lower than MEAs on an
airway in the same quadrant. The higher MEA is NOT due to obstacles in
adjacent quadrants.


MEA's are often higher because of the signal issues of the NAVAIDS
involved. We got an airway here with a 9000' MEA which is way higher
than the obstructions and the MVA because there's something wonky
with the VOR that defines it.
  #5  
Old January 22nd 07, 09:48 PM posted to rec.aviation.ifr
Dan[_1_]
external usenet poster
 
Posts: 211
Default ORCA lower than MEA?

I (and just about everyone else these days) is using an IFR certified
GPS unit, but I suppose we'll be stuck with the VOR technology limits
until ATC moves into the 20th century....

--Dan


Ron Natalie wrote:
Dan wrote:
There are some places on IFR enroute charts where the OROCA (Off-route
obstruction clearance altitude) is actually lower than MEAs on an
airway in the same quadrant. The higher MEA is NOT due to obstacles in
adjacent quadrants.


MEA's are often higher because of the signal issues of the NAVAIDS
involved. We got an airway here with a 9000' MEA which is way higher
than the obstructions and the MVA because there's something wonky
with the VOR that defines it.


  #6  
Old January 22nd 07, 09:51 PM posted to rec.aviation.ifr
Dan[_1_]
external usenet poster
 
Posts: 211
Default ORCA lower than MEA?

I don't suppose this MIA information is avaliable or published
somewhere is it? It would be useful for flight planning.

--Dan



Sam Spade wrote:
Dan wrote:

There are some places on IFR enroute charts where the OROCA (Off-route
obstruction clearance altitude) is actually lower than MEAs on an
airway in the same quadrant. The higher MEA is NOT due to obstacles in
adjacent quadrants.

If I'm on the airway, usually they don't let folks go down to the MOCA,
however if I file direct off-airways, how likely am I to be able to get
the ORCA? The goal is trying to stay below oxygen altitudes in
mountainous terrain while remaining IFR.

--Dan

When you go off-route the center will use is minimum instrument altitude
(MIA) chart. ATC will not use ORCAs; those are a concept that never
went anywhere other than to provide you with some information for
emergency or lost comm use.

Also, you can run into issues if you try to go direct through one of
those many chunks of Class G airspace in the western part of the country.


  #7  
Old January 23rd 07, 12:12 AM posted to rec.aviation.ifr
Ron Natalie
external usenet poster
 
Posts: 1,175
Default ORCA lower than MEA?

Dan wrote:
I (and just about everyone else these days) is using an IFR certified
GPS unit, but I suppose we'll be stuck with the VOR technology limits
until ATC moves into the 20th century....


No you're not. If you're in radar coverage you can go direct to the
other end of the airway (or anywhere else) at any appropriate
minimum IFR altitude. The MEA isn't limitting unless you are
using VOR's to fly the Victor airway.
  #8  
Old January 23rd 07, 01:02 AM posted to rec.aviation.ifr
rps
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Posts: 19
Default ORCA lower than MEA?

Ron Natalie wrote:
Dan wrote:
I (and just about everyone else these days) is using an IFR certified
GPS unit, but I suppose we'll be stuck with the VOR technology limits
until ATC moves into the 20th century....

No you're not. If you're in radar coverage you can go direct to the
other end of the airway (or anywhere else) at any appropriate
minimum IFR altitude. The MEA isn't limitting unless you are
using VOR's to fly the Victor airway.


Doesn't an MEA also guarantee communications reception unless an MRA
indicates a higher altitude? Other altitudes (e.g., OROCA) don't
guarantee radio reception. You can ask for MVA or MIA too, but those
are uncharted. I've asked Flight Service for this info and they've
provided it (after putting me on hold to check with Center).

  #9  
Old January 23rd 07, 01:10 AM posted to rec.aviation.ifr
Ron Natalie
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Posts: 1,175
Default ORCA lower than MEA?

rps wrote:


Doesn't an MEA also guarantee communications reception unless an MRA
indicates a higher altitude?


No. Com reception is not a factor in MEA determination. MRA has
nothing to do with comm either. The MRA tells you that you can
receive the nav signal that is used to define an intersection (from
an off airway navaid).
  #10  
Old January 23rd 07, 01:52 AM posted to rec.aviation.ifr
Sam Spade
external usenet poster
 
Posts: 1,326
Default ORCA lower than MEA?

Dan wrote:
I don't suppose this MIA information is avaliable or published
somewhere is it? It would be useful for flight planning.

No, they guard that stuff like it belongs only to them.
 




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