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.

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.

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).

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).

Ron Natalie wrote:

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).

Wrong. Here is the Victor Airways TERPS:

1718. MINIMUM ENROUTE INSTRUMENT ALTITUDES (MEA). An MEA will be
established for each segment of an airway/route from radio fix to radio
fix. The MEA will be established based upon obstacle clearance over the
terrain or over manmade objects, adequacy of navigation facility
performance, and communications requirements. Segments are designated
West to East and South to North. Altitudes will be established to the
nearest 100 foot increment; that is, 2049 feet becomes 2000, and 2050
feet become 2100.

Sam Spade wrote:
Ron Natalie wrote:

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).

Wrong. Here is the Victor Airways TERPS:

1718. MINIMUM ENROUTE INSTRUMENT ALTITUDES (MEA). An MEA will be
established for each segment of an airway/route from radio fix to radio
fix. The MEA will be established based upon obstacle clearance over the
terrain or over manmade objects, adequacy of navigation facility
performance, and communications requirements. Segments are designated
West to East and South to North. Altitudes will be established to the
nearest 100 foot increment; that is, 2049 feet becomes 2000, and 2050
feet become 2100.

You missed the rest of the line that says "...although adequate
communication at the MEA is not guaranteed." The MRA has nothing
whatsoever to do with communciations requirements.

Ron Natalie wrote:
Sam Spade wrote:

Ron Natalie wrote:

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).


Wrong. Here is the Victor Airways TERPS:

1718. MINIMUM ENROUTE INSTRUMENT ALTITUDES (MEA). An MEA will be
established for each segment of an airway/route from radio fix to
radio fix. The MEA will be established based upon obstacle clearance
over the terrain or over manmade objects, adequacy of navigation
facility performance, and communications requirements. Segments are
designated West to East and South to North. Altitudes will be
established to the nearest 100 foot increment; that is, 2049 feet
becomes 2000, and 2050 feet become 2100.


You missed the rest of the line that says "...although adequate
communication at the MEA is not guaranteed." The MRA has nothing
whatsoever to do with communciations requirements.

That is not pertinent to your statement "No, Com reception is not a
factor in MEA determination." That is just plain wrong.

Then, you go on to discuss MRA. That is a different issue.

Ron Natalie wrote:


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.

He has to have a controller willing to assign him the MIA under the
airway then keep an eye on it all.

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....

Then, once they get comfortable with that, maybe they will move into
this century. ;-)