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Why some approaches are NA as alternates



 
 
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  #1  
Old September 8th 03, 04:07 AM
Ben Jackson
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Default Why some approaches are NA as alternates

What is the reason for an approach (or a whole airport) to be NA as
an alternate? Is there some attribute an approach has to have to be
worthy of being filed as an alternate?

The one that got me wondering was KAST (Astoria, OR) which is NA except
for the VOR Rwy 8 when it also has ILS/LOC and GPS approaches.

--
Ben Jackson

http://www.ben.com/
  #2  
Old September 8th 03, 04:38 AM
Bob Gardner
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I don't have the AST plate, Ben, but I would imagine that the situation is
similar to that on the ILS approach to rwy 17 at Olympia, which is also NA
as an alternate although the other approaches at OLM are OK. ATC cannot
monitor the outer marker for the ILS when the tower is closed, so if it
failed in the middle of the night a pilot shooting the approach would have
no warning that the marker was out of service. The A/FD says that the NDB at
AST is unmonitored...don't know what that has to do with the GPS.

Bob Gardner

"Ben Jackson" wrote in message
news:xnS6b.385577$Ho3.57620@sccrnsc03...
What is the reason for an approach (or a whole airport) to be NA as
an alternate? Is there some attribute an approach has to have to be
worthy of being filed as an alternate?

The one that got me wondering was KAST (Astoria, OR) which is NA except
for the VOR Rwy 8 when it also has ILS/LOC and GPS approaches.

--
Ben Jackson

http://www.ben.com/



  #3  
Old September 8th 03, 04:54 AM
ArtP
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On Mon, 08 Sep 2003 03:38:19 GMT, "Bob Gardner"
wrote:

The A/FD says that the NDB at
AST is unmonitored...don't know what that has to do with the GPS.


A GPS approach is never available as an alternate.

  #4  
Old September 8th 03, 04:46 PM
Bob Gardner
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I don't make the rules (g). The LOM is not required for the miss at either
OLM or AST, but I think it is significant that neither ILS is approved as an
alternate and both LOMs are unmonitored.

Bob Gardner

"Snowbird" wrote in message
om...
"Bob Gardner" wrote in message

news:LQS6b.388806$uu5.73270@sccrnsc04...
I don't have the AST plate, Ben, but I would imagine that the situation

is
similar to that on the ILS approach to rwy 17 at Olympia, which is also

NA
as an alternate although the other approaches at OLM are OK. ATC cannot
monitor the outer marker for the ILS when the tower is closed, so if it
failed in the middle of the night a pilot shooting the approach would

have
no warning that the marker was out of service. The A/FD says that the

NDB at
AST is unmonitored...don't know what that has to do with the GPS.


Bob, why would tne NDB being unmonitored make the alternate NA? Is
that particular NDB required for the MAP?

I thought that if a marker beacon or LOM was OTS, it didn't affect
ILS minima since glideslope intercept is the FAF? Or am I mistaken
about the latter.

A GPS approach is never available as an alternate. If an alternate
is required to be filed, the airport must have other than a GPS
approach available as an alternate and the airplane must be equipped
to fly it. So much for the gov'ts opinion of the wisdom of GPS as
sole-source navigation

Cheers,
Sydney



  #5  
Old September 8th 03, 04:59 PM
Steve
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A GPS approach is never available as an alternate.


That's not true. Your alternate airport needs to have an approach besides
GPS, but that doesn't prevent you from flying the GPS approach at the
alternate airport if the weather is good enough for the GPS approach
minimums.


  #6  
Old September 8th 03, 05:06 PM
ArtP
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On Mon, 08 Sep 2003 15:59:11 GMT, "Steve" wrote:

A GPS approach is never available as an alternate.


That's not true. Your alternate airport needs to have an approach besides
GPS, but that doesn't prevent you from flying the GPS approach at the
alternate airport if the weather is good enough for the GPS approach
minimums.


It doesn't prevent you from flying but it does prevent you from filing
it as an alternate (that's is why they are NA).

  #7  
Old September 9th 03, 06:10 AM
Snowbird
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"Bob Gardner" wrote in message news:hv17b.288320$cF.89187@rwcrnsc53...
I don't make the rules (g). The LOM is not required for the miss at either
OLM or AST, but I think it is significant that neither ILS is approved as an
alternate and both LOMs are unmonitored.


Are the LOC's monitored?

Bob, what happens to the ILS minimums if the LOM is OTS?

No change?

Thanks,
Sydney
  #8  
Old September 11th 03, 05:40 PM
Bob Gardner
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At OLM, there are LOC minima; at AST, the approach is NA if the glideslope
is inoperative, which wipes out any chance of a LOC approach. I would guess
that the localizers ARE monitored, because in doing some other research I
ran across the ILS at Galesburg, IL, where the ILS is NA as an alternate
because the localizer is not monitored.

BTW, e-mails to the address in your header bounce.

Bob Gardner

"Snowbird" wrote in message
om...
"Bob Gardner" wrote in message

news:hv17b.288320$cF.89187@rwcrnsc53...
I don't make the rules (g). The LOM is not required for the miss at

either
OLM or AST, but I think it is significant that neither ILS is approved

as an
alternate and both LOMs are unmonitored.


Are the LOC's monitored?

Bob, what happens to the ILS minimums if the LOM is OTS?

No change?

Thanks,
Sydney



  #9  
Old September 14th 03, 02:01 PM
Snowbird
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Default

"Bob Gardner" wrote in message et...
At OLM, there are LOC minima; at AST, the approach is NA if the glideslope
is inoperative, which wipes out any chance of a LOC approach. I would guess
that the localizers ARE monitored, because in doing some other research I
ran across the ILS at Galesburg, IL, where the ILS is NA as an alternate
because the localizer is not monitored.


Bob,

What happens to the ILS minimia when the outer marker is inop?

BTW, e-mails to the address in your header bounce.


It's a defunct address, use the other one you have, sorry.

Cheers,
Sydney
 




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