Alternate airports

[Mike W.]

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?

[Peter Duniho]

"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

[Andrew Sarangan]

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?
>
>

[Peter Duniho]

"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

[Andrew Sarangan]

"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.

[Peter Duniho]

"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

[Jose]

> 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.

[Peter Duniho]

"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

[OtisWinslow]

"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.

[Jose]

> "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.

[Michael]

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

Actually, that's not quite right. The A-NA refers to the approach, not
the airport. It is quite common to have some approaches to a given
airport marked A-NA, and others not so marked. In that case, the
'best' approach among those not marked A-NA is used to determine
alternate minima for that airport. If all approaches are marked A-NA,
then the only remaining approach is a visual. The alternate minima for
a visual are weather sufficient for descent from MEA to a landing under
basic VFR. Those minima are always authorized, so any airport is an
authorized alternate - the only question is what the alternate minima
will be. There are airports where the alternate minima require 10,000'
ceilings (mountain MEA's and valley airports will do that) but they are
still authorized.

I agree with you that there are not any airports within a short
distance of DAY that would be useful alternates in conditions that
would actually require you to file an alternate for DAY.

Michael

[jsmith]

An different example of this was Port Columbus International in Columbus
OH (KCMH).
CMH had one 10,000 foot runway and one 6,000 foot parallel runway (it
now has the 6,000 extended to 8,000). Because the 6k runway was too
short for most airliners, the airline company operations manuals forbid
their Captains from filing CMH as an alternate in the event the 10k
runway was taken out of service.

Michael wrote:
> Actually, that's not quite right. The A-NA refers to the approach, not
> the airport. It is quite common to have some approaches to a given
> airport marked A-NA, and others not so marked. In that case, the
> 'best' approach among those not marked A-NA is used to determine
> alternate minima for that airport. If all approaches are marked A-NA,
> then the only remaining approach is a visual. The alternate minima for
> a visual are weather sufficient for descent from MEA to a landing under
> basic VFR. Those minima are always authorized, so any airport is an
> authorized alternate - the only question is what the alternate minima
> will be. There are airports where the alternate minima require 10,000'
> ceilings (mountain MEA's and valley airports will do that) but they are
> still authorized.
> I agree with you that there are not any airports within a short
> distance of DAY that would be useful alternates in conditions that
> would actually require you to file an alternate for DAY.

[Andrew]

Peter Duniho wrote:
> "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.

OK, I may show my ignorance here. Isn't the approach procedures
constitute FAR 97? If a chart says 'Alternate Not Authorized', does it
not effectively disallow that airport from being listed as an
alternate?



>
> > 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.

I agree with you on that. Alternate should be selected where the wx is
likely to be significantly different.

[Peter Duniho]

"Andrew" > wrote in message
ups.com...
> OK, I may show my ignorance here. Isn't the approach procedures
> constitute FAR 97? If a chart says 'Alternate Not Authorized', does it
> not effectively disallow that airport from being listed as an
> alternate?

The "not authorized" applies to the approach, not the airport (as Michael
already pointed out). Forecast VFR conditions allow ANY airport to qualify
as an alternate under the default visual approach that exists at every
airport.

If you have an airport for which every approach says "not authorized", then
the visual approach is the only way to use that airport as an alternate.
But even in that case, the airport is not ruled out as an alternate, except
due to the weather forecast. It is otherwise eligible.

Note that airports without instrument approaches don't even have a chart
where one could find "A-NA" listed on it. As much as I hate to bring logic
into a discussion about the FARs, it just wouldn't make sense for an airport
with an instrument approach to not be authorized as an alternate (even under
VFR conditions), even as one without is automatically granted qualification
as an alternate (under 91.169).

So, to reiterate: having one or more approaches at an airport listed as
"A-NA" does not disqualify the airport. It just disqualifies the approach.
And the visual approach is always authorized (since it doesn't rely on any
monitored navigation equipment, and an area forecast is sufficient for using
for alternate decision-making).

Pete

[Jim Burns]

Good job Pete.
Alternate airport, not alternate approach.

http://www.aopa.org/pilot/features/ii_9807.html
AOPA's article on the subject. It points out that FSS is a good place to
start asking for alternate suggestions as they have the forecasts right in
front of them.

When I file and am required to list an alternate, the first line of thought
that goes through my mind is "why" I need an alternate.... What weather
phenomenon has created the conditions, is it moving, which direction, and
how fast?

A wide area of like conditions forcast to remain the same or deteriorate
will usually tell me to pick an alternate that is enroute prior to my
original destination, however, if my original destination is in a low lying
area, near water and possibly surrounded by ground fog, an airport close by
but at a higher elevation may be the ticket. Same theory for lake effect
snow, go where it isn't! I'm usually better off filing an alternate further
inland than along the lake even though I will be going past my original
destination. I also try to pick alternate airports that have more services
than my original destination, if the weather is bad enough that I can't get
into Podunk on their VOR or GPS approach I know that the weather is worse
than forecast and my alternate will be the closest ILS with radar but
hopefully in the direction of more favorable conditions. Note that once
choosing the alternate the weather at the alternate then must meet the non
precision 800/2 and precision 600/2 rule. But to steal a line from AOPA's
article "It is also worth noting here that alternate minimums apply for
planning purposes alone. If you're airborne and heading to the alternate,
published minimums will now apply."

Jim

[Ross Richardson]

Peter Duniho wrote:

>"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
>
>
>
>
We have a local airport (KGYI) with an ILS and it does apply as an
alternate. At the time it didn't have weather reporting, but now has a AWOS

--
Regards,

Ross
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