Why some approaches are NA as alternates

[Ben Jackson]

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/

[Bob Gardner]

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/

[ArtP]

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.

[Bob Gardner]

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

[Steve]

> 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.

[ArtP]

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).

[Snowbird]

"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

[Bob Gardner]

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

[Snowbird]

"Bob Gardner" > wrote in message >...
> 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

[Ron Rosenfeld]

On 14 Sep 2003 06:01:42 -0700, (Snowbird) wrote:

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

In the US, there is no penalty if the OM is OTS (or the MM for that
matter).

However, for a LOC approach, if there is no alternative method of
identifying the FAF, it may not be flyable.


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