Alternate airports

OK I picked this topic after reading through the 'flying to hamvention''
thread. Being a non-instrument rated private pilot, not sure what
constitutes a 'legal' alternate airport. If VFR, weather minimums must be
met just to get there. If IFR, I assume there is visibility minimum
(decision height?) that could cause a plane to not be able to land using ILS
or whatever. So what is the process for choosing an alternate?

"Mike W." wrote in message
...
[...] So what is the process for choosing an alternate?

It can be quite complex, especially for Part 91 because so much is left to
pilot discretion. Basically, an alternate needs to be forecast to meet the
requirements given for that airport (its "alternate airport minima"
specified for a given instrument approach at the airport). One is not even
required to have an alternate if the intended destination meets some basic
weather forecast requirements. See FAR 91.169 for the nitty-gritty.

However, in reality what you're trying to do when selecting an alternate is
to provide for a genuine Plan B. This means you need to consider the
weather that is causing you to want an alternate in the first place, and to
pick an airport that will not be similarly affected. This may mean picking
one that's not in the same valley, on the same side of a mountain range,
near the ocean shore, etc. Of course, you also need to pick an airport that
is suitable for your airplane and your piloting skills.

A person could write a whole chapter in an IFR training manual on the topic.
Between this post and many others you'll get, maybe you'll get an inkling of
what's actually involved.

Pete

If the destination does not have an instrument approach you must pick an
alternate.

If the destination has an instrument approach, then you don't need an
alternate unless the the weather is worse than 2000' ceiling or 3SM vis
+/1hr of the ETA. (ie if the forecast is worse than VFR then you need an
alternate).

You can't pick any airports as an alternate. Only a few airports qualify
as an alternate.



"Mike W." wrote in
:

OK I picked this topic after reading through the 'flying to
hamvention'' thread. Being a non-instrument rated private pilot, not
sure what constitutes a 'legal' alternate airport. If VFR, weather
minimums must be met just to get there. If IFR, I assume there is
visibility minimum (decision height?) that could cause a plane to not
be able to land using ILS or whatever. So what is the process for
choosing an alternate?

"Andrew Sarangan" wrote in message
1...
If the destination does not have an instrument approach you must pick an
alternate.

If the destination has an instrument approach, then you don't need an
alternate unless the the weather is worse than 2000' ceiling or 3SM vis
+/1hr of the ETA. (ie if the forecast is worse than VFR then you need an
alternate).

The above is not "the process for choosing an alternate". It's the process
for deciding whether you NEED an alternate.

You can't pick any airports as an alternate. Only a few airports qualify
as an alternate.

Wrong. Any airport qualifies, as long as the forecast is for VFR conditions
from the descent from MEA all the way to the ground. Beyond that, lots of
airports have instrument approaches and thus qualify as an alternate under
lower forecast conditions. Even in IFR conditions, it's far from true that
"only a few airports qualify as an alternate".

Pete

"Peter Duniho" wrote in
:

"Andrew Sarangan" wrote in message
1...
If the destination does not have an instrument approach you must pick
an alternate.

If the destination has an instrument approach, then you don't need an
alternate unless the the weather is worse than 2000' ceiling or 3SM
vis +/1hr of the ETA. (ie if the forecast is worse than VFR then you
need an alternate).

The above is not "the process for choosing an alternate". It's the
process for deciding whether you NEED an alternate.

But you have to first decide whether you need an alternate before going
to the trouble of picking one.


You can't pick any airports as an alternate. Only a few airports
qualify as an alternate.

Wrong. Any airport qualifies, as long as the forecast is for VFR
conditions from the descent from MEA all the way to the ground.
Beyond that, lots of airports have instrument approaches and thus
qualify as an alternate under lower forecast conditions. Even in IFR
conditions, it's far from true that "only a few airports qualify as an
alternate".

Pete


Any airport does not qualify. Most of those airports have "A-NA" on the
chart, which stands for "Alternate - Not Authorized".

The thread was a follow-up to 'flying to hamvention' thread. If you look
at the Dayton area, there aren't any airports within a short distance of
DAY that does not have an "A-NA" on it.

"Andrew Sarangan" wrote in message
1...
But you have to first decide whether you need an alternate before going
to the trouble of picking one.

So?

Any airport does not qualify. Most of those airports have "A-NA" on the
chart, which stands for "Alternate - Not Authorized".

FAR 91.169 doesn't say anything about whether an alternate is authorized or
not. ANY airport is authorized, as long as VFR conditions from MEA to
landing are forecast.

The thread was a follow-up to 'flying to hamvention' thread. If you look
at the Dayton area, there aren't any airports within a short distance of
DAY that does not have an "A-NA" on it.

Ideally, an alternate would not be a short distance from your destination
anyway. After all, if the weather's too poor for landing at your
destination, often it will be at a nearby airport as well.

In any case, while something in that thread brought this to the original
poster's attention, the fact that he posted in a new thread implies to me
that he intended the question as a general one, not specific to that
particular destination.

Pete

Ideally, an alternate would not be a short distance from your destination
anyway. After all, if the weather's too poor for landing at your
destination, often it will be at a nearby airport as well.

Not necessarily, IMHO. If the airport you are aiming for has high
minima (such as an NDB approach into the hills), and right nearby there
is an airport with low minima (such as an ILS), then under many weather
circumstances it is quite reasonable to use the neighboring airport as
an alternate.

OTOH, if the weather system is wide and threatens to possibly go low
(probably all over), then such a choice is... er... less optimal. You'd
want an airport (and the gas to get there) that is outside the weather
system.

The excercise of choosing a "legal" alternate has more to do with gas
than anything else. You need the gas to get there, and still fly almost
an hour at full cruise. Once you're in the air, and you actually =need=
an alternatative landing site, you can use any airport as that
alternative landing site, no matter what you filed in your flight plan
as a legal alternate, and no matter whether or not the airport is A-NA
on the charts. It just becomes an ordinary destination (albeit an
unplanned one)

Jose
--
Get high on gasoline: fly an airplane.
for Email, make the obvious change in the address.

"Jose" wrote in message
. com...
Ideally, an alternate would not be a short distance from your destination
anyway. After all, if the weather's too poor for landing at your
destination, often it will be at a nearby airport as well.

Not necessarily, IMHO.

"Often" is not the same as "always". I already pointed out in my initial
reply that choosing an alternate is a complex exercise. It is pointless of
you to take me to task for a comment that was obviously not meant to cover
all the bases.

Pete

"Peter Duniho" wrote in message
...
However, in reality what you're trying to do when selecting an alternate
is to provide for a genuine Plan B. This means you need to consider the
weather that is causing you to want an alternate in the first place, and
to pick an airport that will not be similarly affected. Pete

I think Pete has a bit of key advice here. I favor picking one along my
route of flight but prior to my destination. That way if things are going
south
at the destination you can just land at the alternate and take a
look at alternatives.

"Often" is not the same as "always". I already pointed out in my initial
reply that choosing an alternate is a complex exercise. It is pointless of
you to take me to task for a comment that was obviously not meant to cover
all the bases.

Well, I wasn't "taking you to task". And my reply was not so much to
=you= as to the idea, often repeated as a mantra, that an alternate
should be outside the weather system to be really useful.

Jose
--
Get high on gasoline: fly an airplane.
for Email, make the obvious change in the address.