MEA Navaid Guarantee?

[vdehart]

Hello,

I've searched everywhere and can't seem to get a firm answer to the following question...

I realize that the MEA guarantees navaid reception along an airway, but does this mean it guarantees the reception of both navaids along the entire length of an airway if there is no changeover point? For example, if instead of switching halfway between the VORs as I've been instructed, could I just choose to continue to fly "FROM" VOR ABC all the way until I reach the other VOR and still get a signal from the VOR I'm flying from? A great example of this seems to be northbound from PXN to ECA ON V113 in Central Califoria. In this situation I would have to use the 328 radial from PXN for the entire segment because the 147 radial off ECA isn't usable as indicated.

Thank you! Any help is appreciated.

 

[luvflyin]

If the changeover point isn't charted, then it is halfway. This one has me scratchin my head. PXN is within the service volume. Maybe they're telling us we can use PXN for the whole segement. It would get kinda interesting identifying station passage over ECA though. ECA is unusable from 126 through 180. Maybe the point is don't fly it with VOR only. It does give the GPS minimum altitude on the PATYY ECA segements.

 

[dmspilot]

Look at LVL, there are some unusable radials in which case the low enroute tells you to substitute the other radials to fly the airways. No such designation is shown in OP's case. (Interestingly, the LVL VOR has been NOTAMed for more than two years as out of service permanently.)

With that in mind I would guess you could not fly that airway without GPS.

 

[roncachamp]

I realize that the MEA guarantees navaid reception along an airway, but does this mean it guarantees the reception of both navaids along the entire length of an airway if there is no changeover point?

No.

For example, if instead of switching halfway between the VORs as I've been instructed, could I just choose to continue to fly "FROM" VOR ABC all the way until I reach the other VOR and still get a signal from the VOR I'm flying from?

No.

A great example of this seems to be northbound from PXN to ECA ON V113 in Central Califoria. In this situation I would have to use the 328 radial from PXN for the entire segment because the 147 radial off ECA isn't usable as indicated.

The PXN R-328 has an Expanded Service Volume to 70 miles. ISTM the note at the R-147 should include that info. Something like "R-147 UNUSABLE USE PXN R-328".

 

[MAKG1]

PXN is among a lot of terrain. Does the expanded service volume take that into account? Without the charting note, I would NOT assume it's good.

 

[luvflyin]

No.



No.



The PXN R-328 has an Expanded Service Volume to 70 miles. ISTM the note at the R-147 should include that info. Something like "R-147 UNUSABLE USE PXN R-328".

LVL that @dmspilot mentions above has those notes on the chart telling you what to do. Looks like maybe this is another charting error. PXN is an (L) VORTAC. I wouldn't think "expanded service volume" would be needed.

 

[aterpster]

LVL that @dmspilot mentions above has those notes on the chart telling you what to do. Looks like maybe this is another charting error. PXN is an (L) VORTAC. I wouldn't think "expanded service volume" would be needed.

Could be the treatment at LVL wouldn't pass flight inspection for this segment of V-113. Seems like this airway should be considered unusable without IFR certified en route GPS/RNAV.

Many VOR stations have become less useful with age.

 

[roncachamp]

PXN is among a lot of terrain. Does the expanded service volume take that into account? Without the charting note, I would NOT assume it's good.

Yes. The request for an ESV goes to spectrum management. If it works there in theory it's then forwarded to flight check to be proved.

 

[luvflyin]

LVL that @dmspilot mentions above has those notes on the chart telling you what to do. Looks like maybe this is another charting error. PXN is an (L) VORTAC. I wouldn't think "expanded service volume" would be needed.

Oops. I had the wrong numbers on L service volumes. 40 miles it is

 

[roncachamp]

LVL that @dmspilot mentions above has those notes on the chart telling you what to do. Looks like maybe this is another charting error. PXN is an (L) VORTAC. I wouldn't think "expanded service volume" would be needed.

An L class VOR has a usable distance of 40 miles 18,000 feet above the NAVAID and lower. It's 70 miles from PXN to ECA. With the ECA R-147 unusable there could be no airway without the ESV on the PXN R-328.

 

[luvflyin]

It looks like PXN must have Service Volume out to at least 94 miles. Checkout V301

 

[luvflyin]

An L class VOR has a usable distance of 40 miles 18,000 feet above the NAVAID and lower. It's 70 miles from PXN to ECA. With the ECA R-147 unusable there could be no airway without the ESV on the PXN R-328.

yeah. My memory was confusing H and L

 

[roncachamp]

It looks like PXN must have Service Volume out to at least 94 miles. Checkout V301

A request for an ESV does not push out the full 360 degree output of the SSV to whatever value is needed. It applies only to the needed radials. V301 is 94 miles long between PXN and OAK but that segment has a dogleg; the PXN R-302 is used for 73 miles to the bend. The PXN datasheet shows an ESV on the R-301 for 73 miles. Yes, there's an error of some kind here. Perhaps someone confused radial with airway number.

 

[roncachamp]

yeah. My memory was confusing H and L

The SSV of an H class VOR is 100 miles between 18,000 and 14,500 feet above the facility. Below that it's the same 40 miles as an L class.

 

[luvflyin]

A request for an ESV does not push out the full 360 degree output of the SSV to whatever value is needed. It applies only to the needed radials. V301 is 94 miles long between PXN and OAK but that segment has a dogleg; the PXN R-302 is used for 73 miles to the bend. The PXN datasheet shows an ESV on the R-301 for 73 miles. Yes, there's an error of some kind here. Perhaps someone confused radial with airway number.

Yeah. It is 73. I misread the chart. It was the 301 radial when it was first established.

 

[MAKG1]

PXN is used on almost every IFR flight between LA and the Bay Area. It's on "preferred IFR routes." It's an important navaid, so the expanded service volumes make sense.

And hot damn there is a lot of traffic there. I had to hold near there (VFR) for an air defense exercise once, for hours. I insisted on moving the hold point 10 miles south, as we were otherwise right in the way.

 

[Palmpilot]

The PXN R-328 has an Expanded Service Volume to 70 miles.

Where did you find that information?

ISTM the note at the R-147 should include that info. Something like "R-147 UNUSABLE USE PXN R-328".

I notice there's a GPS MEA "3000G" on that route segment. Maybe they meant that to indicate that GPS should be used there.

 

[roncachamp]

Where did you find that information?

From the PXN datasheet, available here.

I notice there's a GPS MEA "3000G" on that route segment. Maybe they meant that to indicate that GPS should be used there.

A GNSS RNAV MEA that is the same as the standard MEA. My guess would be someone made an unnecessary entry on a document used by the chartmakers.