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).

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:


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. ;-)

On 21 Jan 2007 21:51:03 -0800, "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

Although I've never done it, I have read that in that sort of area you
could request "VFR-on-top". There is no requirement that this sort of
flight be carried out *over* an undercast.

AIM
4-4-7. IFR Clearance VFR-on-top

a. A pilot on an IFR flight plan operating in VFR weather conditions, may
request VFR-on-top in lieu of an assigned altitude. This permits a pilot to
select an altitude or flight level of their choice (subject to any ATC
restrictions.)

....

e. When operating in VFR conditions with an ATC authorization to "maintain
VFR-on-top/maintain VFR conditions" pilots on IFR flight plans must:

1. Fly at the appropriate VFR altitude as prescribed in 14 CFR Section
91.159.

2. Comply with the VFR visibility and distance from cloud criteria in 14
CFR Section 91.155 (Basic VFR Weather Minimums).

3. Comply with instrument flight rules that are applicable to this flight;
i.e., minimum IFR altitudes, position reporting, radio communications,
course to be flown, adherence to ATC clearance, etc.

....

--------------------------------


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

Ron Rosenfeld wrote:

On 21 Jan 2007 21:51:03 -0800, "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


Although I've never done it, I have read that in that sort of area you
could request "VFR-on-top". There is no requirement that this sort of
flight be carried out *over* an undercast.

But, it has to be at, or above the minimum IFR altitude, plus comply
with the VFR altitude rules. Often, that forces you higher than MEA.

On Tue, 23 Jan 2007 05:20:03 -0800, Sam Spade wrote:

Ron Rosenfeld wrote:

On 21 Jan 2007 21:51:03 -0800, "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


Although I've never done it, I have read that in that sort of area you
could request "VFR-on-top". There is no requirement that this sort of
flight be carried out *over* an undercast.

But, it has to be at, or above the minimum IFR altitude, plus comply
with the VFR altitude rules. Often, that forces you higher than MEA.

I've not flown extensively in mountainous areas. Are there really many
airways with MEA's below the minimum 91.177 IFR altitudes for flight?

Or are you saying that ATC would not grant the clearance because of radar
coverage/MIA/MVA issues?


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

Ron Rosenfeld wrote:


I've not flown extensively in mountainous areas. Are there really many
airways with MEA's below the minimum 91.177 IFR altitudes for flight?

There used to be only one choice for On Top. Fly a Victor Airway at a
compliant VFR altitude, and not less than the MEA. Since MEAs are
almost always at X-thousand, you have to fly higher than that to be at a
VFR altitude.

Now, with RNAV-direct common, you have to fly at, or above, the Center's
MIA at a VFR altitude. This, of course, provided the controller will
give you the MIA. ;-)

As to you providing your own 91.177 altitude that just won't work in
controlled airspace if it is lower than the MIA.

Or are you saying that ATC would not grant the clearance because of radar
coverage/MIA/MVA issues?

MIA issues and often radar coverage.

Sam Spade wrote:



Now, with RNAV-direct common, you have to fly at, or above, the Center's
MIA at a VFR altitude.

No.

On Wed, 24 Jan 2007 06:24:32 -0800, Sam Spade wrote:

Ron Rosenfeld wrote:


I've not flown extensively in mountainous areas. Are there really many
airways with MEA's below the minimum 91.177 IFR altitudes for flight?

There used to be only one choice for On Top. Fly a Victor Airway at a
compliant VFR altitude, and not less than the MEA. Since MEAs are
almost always at X-thousand, you have to fly higher than that to be at a
VFR altitude.

Now, with RNAV-direct common, you have to fly at, or above, the Center's
MIA at a VFR altitude. This, of course, provided the controller will
give you the MIA. ;-)

As to you providing your own 91.177 altitude that just won't work in
controlled airspace if it is lower than the MIA.

Or are you saying that ATC would not grant the clearance because of radar
coverage/MIA/MVA issues?

MIA issues and often radar coverage.


It seems to me I heard of OTP flights at low altitudes well before GPS/RNAV
was common.

So far as the Victor Airway is concerned, my understanding is that it does
not officially exist below the MEA.

So far as VFR cruising altitudes are concerned, if one is below the MEA,
that may or may not apply, depending on AGL altitude.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)