MRA Question

Hi,

Reference IFR enroute L-1, panel C (64 south of SEA), MALAY
intersection is defined by:

The intersection of V23 and V287, each having an MEA of no higher than
6000;
DME distances on each of the airways; and
A cross-radial from the Astoria VOR, located ~55 NM west of the
intersection.

MALAY has an MRA of 9500.

Question: if MEA ensures an adequate navigation signal at 6000, then
why the MRA of 9500?
If I'm equipped /U, can I fly V23-MALAY-V287 (or reversed) below 9500?

Thanks in advance!

On 04/15/06 10:18, wrote:
Hi,

Reference IFR enroute L-1, panel C (64 south of SEA), MALAY
intersection is defined by:

I don't have that chart, so I can't look at the specific case, but...


The intersection of V23 and V287, each having an MEA of no higher than
6000;
DME distances on each of the airways; and
A cross-radial from the Astoria VOR, located ~55 NM west of the
intersection.

MALAY has an MRA of 9500.

Question: if MEA ensures an adequate navigation signal at 6000, then
why the MRA of 9500?

The MRA is defined so that you can navigate the airway, it's defined so
you can receive the off-airway station which is used to define the
intersection for fix.

If I'm equipped /U, can I fly V23-MALAY-V287 (or reversed) below 9500?

Do you need to be able to identify the fix? Without seeing the chart, I'm
not sure. If you do, then you just need some way to identify it - what
method you use is up to you. If you can't receive the off-airway station,
then DME would work.

Basically, if you need to identify that fix with the off-airway navaid,
then you need to be at the MRA to be sure you'll receive the station.



Thanks in advance!



--
Mark Hansen, PP-ASEL, Instrument Airplane
Cal Aggie Flying Farmers
Sacramento, CA

On 04/15/06 10:33, Mark Hansen wrote:
On 04/15/06 10:18, wrote:
Hi,

Reference IFR enroute L-1, panel C (64 south of SEA), MALAY
intersection is defined by:

I don't have that chart, so I can't look at the specific case, but...


The intersection of V23 and V287, each having an MEA of no higher than
6000;
DME distances on each of the airways; and
A cross-radial from the Astoria VOR, located ~55 NM west of the
intersection.

MALAY has an MRA of 9500.

Question: if MEA ensures an adequate navigation signal at 6000, then
why the MRA of 9500?

The MRA is defined so that you can navigate the airway, it's defined so

Oops, I meant to say "The MRA is *not* defined so that you can navigate
the airway..."

sorry about the confusion.

you can receive the off-airway station which is used to define the
intersection for fix.

If I'm equipped /U, can I fly V23-MALAY-V287 (or reversed) below 9500?

Do you need to be able to identify the fix? Without seeing the chart, I'm
not sure. If you do, then you just need some way to identify it - what
method you use is up to you. If you can't receive the off-airway station,
then DME would work.

Basically, if you need to identify that fix with the off-airway navaid,
then you need to be at the MRA to be sure you'll receive the station.



Thanks in advance!





--
Mark Hansen, PP-ASEL, Instrument Airplane
Cal Aggie Flying Farmers
Sacramento, CA

wrote:
Hi,

Reference IFR enroute L-1, panel C (64 south of SEA), MALAY
intersection is defined by:

The intersection of V23 and V287, each having an MEA of no higher than
6000;
DME distances on each of the airways; and
A cross-radial from the Astoria VOR, located ~55 NM west of the
intersection.

MALAY has an MRA of 9500.

Question: if MEA ensures an adequate navigation signal at 6000, then
why the MRA of 9500?
If I'm equipped /U, can I fly V23-MALAY-V287 (or reversed) below 9500?

Thanks in advance!


Assuming Slant/U:

It's a bit confusing because MALAY is located at the turn point of those
airways. But, the turn point does not have to meet the same fix
tolerances as an intersection must meet for reporting or holding.

You would treat this as any another non-compulsory reporting point.
There is no requirement for you to file an altitude that will meet the
reception requirements of a non-compulsory reporting point, nor would
ATC require you to report or hold at that fix if you are assigned an
altitude below 9,500.

You do not need to identy MALAY to make the course change for V-23.
But, since MALAY is also an MEA change point for V-23 you could not use
the lower MEA (applicable only to a cruise clearance or lost comm) until
you had determined with certainty by other means that you were in the
airway segment with the lower MEA. Two-way MEAs in both segments of
V-23 doesn't make it any easier but, again, that is usually academic.