Alternate minimums same as forecast weather

wrote in
:

Stan, here in Canada, the forecast weather at your alternate must be
at least 300 feet and 1 mile above the approach minimums (or 600/2 or
800/2, whichever is higher). Supposedly to help ensure you can make
it in at your alternate. A kind of buffer.
I was just surprised to see that in the US, there are no such
additives.
And so, the alternate weather limits in the US can be the same as the
approach limits, in a very **FEW** cases.
CRQ was an example I found.
As an explanation to why it is only in a "few" cases, I notice in the
US that alternate weather limits must be at or above circling approach
limits too. And so, **normally** you find straight in approach limits
are less that alternate weather limits.
Canada does not have that circling minimums requirement as part of
alternate weather requirements.

In general, airports use standard alternate minimums, and the required
alternate minimums are listed on the back of the airport diagram. I must
confess that I really haven't read or worried about Part 91 alternate
minimums in a very long time, because I don't use them. My alternate
minimums are in my ops manual and ops specs. We add 200' to the
published approach minimum altitude for the approach we intend to use,
and use either 1 mile vis or published, whichever is higher, and only are
required to have 30 minutes reserve at the alternate. So for most
airports with an ILS, the alternate minimums are 400/1. As you can see,
there isn't a huge margin for error here. Fortunately, a diversion to
the alternate is rare, since we can cut the published visibility in half,
and since it's legal to descend to 100' above the TDZE with the approach
lights in sight, a miss off the ILS is seldom required, especially at
night, and I have never done one except on checkrides.

Flying a spam can for pleasure rather than profit is a very different
thing, though.

--
Regards,

Stan

"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety." B. Franklin

So is this all ok?

Stan

Usually yes. Keep in mind, your FILED alternate does not have to be the
actual field you divert to. You simply have to have "ON PAPER" a field
that is within your capabilities (fuel) and specified weather conditions.

There may be DOZENS of other fields nearby/in range that are safe and
useable, but are unable to be listed as legal alternates.

I say usually. A big part of this decision is what the weather is across
the region. Is the entire region socked in low/hard or is there a
localized weather phenom that will move on/clear up/etc?

From a legal standpoint, its good to go. From a safety standpoint, its
all relative. If it doesnt worsen, its just as safe as any other IFR
flight to near minimums. If the whole region is blanketed by low clouds
you may shut yourself out.

With regards to your example (assuming ILS our at Carlsbad), as a
general rule, I would want to have an alternate that had a working ILS
with good precision minimums available to me, so that there is a large
margin between the higher "alternate" minimums and the actual minimums
that I will fly the approach to.

Dave

I always like to have a very good VFR alternate I can find
with nothing more than a working compass and clock. I
probably would not go to a filed alternate unless I had a
total radio/electrical failure. Often the airport at my
destination with the lowest minimums isn't the airport where
the cars are parked. Also, often in the foggy season, the
entire plains and Mississippi Valley are at a steady and
stable 400 feet and 1-2 miles in fog and stratus. The
nearest airport with alternate minimums (600-2 or 800-2) may
be several hundred miles away, which means that a big
turbo-prop or jet is needed just to fly from Wichita to
Kansas City, since the alternate is beyond fuel range.


--
James H. Macklin
ATP,CFI,A&P

--
The people think the Constitution protects their rights;
But government sees it as an obstacle to be overcome.
some support
http://www.usdoj.gov/olc/secondamendment2.htm
See http://www.fija.org/ more about your rights and duties.


"Dave S" wrote in message
et...
|
| So is this all ok?
|
| Stan
|
| Usually yes. Keep in mind, your FILED alternate does not
have to be the
| actual field you divert to. You simply have to have "ON
PAPER" a field
| that is within your capabilities (fuel) and specified
weather conditions.
|
| There may be DOZENS of other fields nearby/in range that
are safe and
| useable, but are unable to be listed as legal alternates.
|
| I say usually. A big part of this decision is what the
weather is across
| the region. Is the entire region socked in low/hard or is
there a
| localized weather phenom that will move on/clear up/etc?
|
| From a legal standpoint, its good to go. From a safety
standpoint, its
| all relative. If it doesnt worsen, its just as safe as any
other IFR
| flight to near minimums. If the whole region is blanketed
by low clouds
| you may shut yourself out.
|
| With regards to your example (assuming ILS our at
Carlsbad), as a
| general rule, I would want to have an alternate that had a
working ILS
| with good precision minimums available to me, so that
there is a large
| margin between the higher "alternate" minimums and the
actual minimums
| that I will fly the approach to.
|
| Dave

File what you have to, fly what you need to. Let's not try to solve
decision making issues with regulation.

-Robert

This issue is raised in AIM 5.1.9(b) anyway:

b. The FAA has identified three possible situations where the failure
to plan for an alternate airport when flying IFR to such a destination
airport could result in a critical situation if the weather is less
than forecast and sufficient fuel is not available to proceed to a
suitable airport.
1. An IFR flight to an airport where the Minimum Descent Altitudes
(MDAs) or landing visibility minimums for all instrument approaches are
higher than the forecast weather minimums specified in 14 CFR Section
91.167(b). For example, there are 3 high altitude airports in the U.S.
with approved instrument approach procedures where all of the MDAs are
greater than 2,000 feet and/or the landing visibility minimums are
greater than 3 miles (Bishop, California; South Lake Tahoe, California;
and Aspen-Pitkin Co./Sardy Field, Colorado). In the case of these
airports, it is possible for a pilot to elect, on the basis of
forecasts, not to carry sufficient fuel to get to an alternate when the
ceiling and/or visibility is actually lower than that necessary to
complete the approach.
2. A small number of other airports in mountainous terrain have MDAs
which are slightly (100 to 300 feet) below 2,000 feet AGL. In
situations where there is an option as to whether to plan for an
alternate, pilots should bear in mind that just a slight worsening of
the weather conditions from those forecast could place the airport
below the published IFR landing minimums.
3. An IFR flight to an airport which requires special equipment; i.e.,
DME, glide slope, etc., in order to make the available approaches to
the lowest minimums. Pilots should be aware that all other minimums on
the approach charts may require weather conditions better than those
specified in 14 CFR Section 91.167(b). An inflight equipment
malfunction could result in the inability to comply with the published
approach procedures or, again, in the position of having the airport
below the published IFR landing minimums for all remaining instrument
approach alternatives.

I would not like to see the FAA change the rules to handle
these exceptions, but a good pilot will note the conditions
and always plan for the worst. Even in perfectly clear
skies, Aspen is still just ONE runway. If there is a gear
up landing, you will go to an alternate.
If the weather is IFR at 800-2 and you're in the soup when
the airport equipment fails, you'll go to an alternate.

Whether that alternate is 10 miles away or 800 depends on
where you are flying and how much fuel you can carry.


--
James H. Macklin
ATP,CFI,A&P

--
The people think the Constitution protects their rights;
But government sees it as an obstacle to be overcome.
some support
http://www.usdoj.gov/olc/secondamendment2.htm
See http://www.fija.org/ more about your rights and duties.


wrote in message
oups.com...
| This issue is raised in AIM 5.1.9(b) anyway:
|
| b. The FAA has identified three possible situations where
the failure
| to plan for an alternate airport when flying IFR to such a
destination
| airport could result in a critical situation if the
weather is less
| than forecast and sufficient fuel is not available to
proceed to a
| suitable airport.
| 1. An IFR flight to an airport where the Minimum Descent
Altitudes
| (MDAs) or landing visibility minimums for all instrument
approaches are
| higher than the forecast weather minimums specified in 14
CFR Section
| 91.167(b). For example, there are 3 high altitude airports
in the U.S.
| with approved instrument approach procedures where all of
the MDAs are
| greater than 2,000 feet and/or the landing visibility
minimums are
| greater than 3 miles (Bishop, California; South Lake
Tahoe, California;
| and Aspen-Pitkin Co./Sardy Field, Colorado). In the case
of these
| airports, it is possible for a pilot to elect, on the
basis of
| forecasts, not to carry sufficient fuel to get to an
alternate when the
| ceiling and/or visibility is actually lower than that
necessary to
| complete the approach.
| 2. A small number of other airports in mountainous terrain
have MDAs
| which are slightly (100 to 300 feet) below 2,000 feet AGL.
In
| situations where there is an option as to whether to plan
for an
| alternate, pilots should bear in mind that just a slight
worsening of
| the weather conditions from those forecast could place the
airport
| below the published IFR landing minimums.
| 3. An IFR flight to an airport which requires special
equipment; i.e.,
| DME, glide slope, etc., in order to make the available
approaches to
| the lowest minimums. Pilots should be aware that all other
minimums on
| the approach charts may require weather conditions better
than those
| specified in 14 CFR Section 91.167(b). An inflight
equipment
| malfunction could result in the inability to comply with
the published
| approach procedures or, again, in the position of having
the airport
| below the published IFR landing minimums for all remaining
instrument
| approach alternatives.
|

800-2 at Aspen? Not for me!
If KASE flirts with 2000-3, I'm going to my alternate.
Not much different for Eagle County, either.
I've diverted to Grand Junction and Montrose several times.

"Jim Macklin" wrote in message news:UWLKf.102996$4l5.42576@dukeread05...

.... Even in perfectly clear
skies, Aspen is still just ONE runway. If there is a gear
up landing, you will go to an alternate.
If the weather is IFR at 800-2 and you're in the soup when
the airport equipment fails, you'll go to an alternate.
--
James H. Macklin
ATP,CFI,A&P