Why some approaches are NA as alternates

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