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Alternate Mimimums?



 
 
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  #1  
Old December 24th 03, 01:53 PM
smf
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Default Alternate Mimimums?

What exactly does the /A\na on approach plates mean. I know it says
Alternate minimums not authorized. Does it mean the airport can't be used as
an alternate?


thanks

Steve




  #2  
Old December 24th 03, 05:47 PM
KevinChandler
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It means that this airport cannot be used as an alternate for an IFR flight
plan. It can be used as the primary destination; however, it can not be
used as an alternate. Keep in mind, alternate airports are only required in
certain weather conditions.

"smf" wrote in message
news:F_hGb.22853$HQ.7869@okepread02...
What exactly does the /A\na on approach plates mean. I know it says
Alternate minimums not authorized. Does it mean the airport can't be used

as
an alternate?


thanks

Steve






  #3  
Old December 24th 03, 06:05 PM
Ron Natalie
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"KevinChandler" wrote in message ...
It means that this airport cannot be used as an alternate for an IFR flight
plan. It can be used as the primary destination; however, it can not be
used as an alternate. Keep in mind, alternate airports are only required in
certain weather conditions.


It means it can't be the legally required alternate for filing a flight plan.
An alternate is required when any of the following is true:

1. The weather forecast for the ETA +/- hour isn't going to be 2000' and 3 miles
(1-2-3) rule.
2. The destination has no published approach.

In addition to the alternate NA restrictions, the alternate must be served
by an approach you are equipped for that does not involve GPS.

Of course, all of this only applies to the legal requirements for filing a plan
and computing the required fuel. Where you actually go if you can't get
into your destination is unaffected by what you put down as an alternate.

  #4  
Old December 24th 03, 07:24 PM
Tarver Engineering
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"Ron Natalie" wrote in message
m...

"KevinChandler" wrote in message

...
It means that this airport cannot be used as an alternate for an IFR

flight
plan. It can be used as the primary destination; however, it can not be
used as an alternate. Keep in mind, alternate airports are only

required in
certain weather conditions.


It means it can't be the legally required alternate for filing a flight

plan.
An alternate is required when any of the following is true:

1. The weather forecast for the ETA +/- hour isn't going to be 2000' and

3 miles
(1-2-3) rule.
2. The destination has no published approach.

In addition to the alternate NA restrictions, the alternate must be served
by an approach you are equipped for that does not involve GPS.


Isn't the GPS rule only true if your primary destination used a GPS
approach?

Of course, all of this only applies to the legal requirements for filing a

plan
and computing the required fuel. Where you actually go if you can't get
into your destination is unaffected by what you put down as an alternate.



  #5  
Old December 24th 03, 08:08 PM
PaulaJay1
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In article , "KevinChandler"
writes:

It means that this airport cannot be used as an alternate for an IFR flight
plan. It can be used as the primary destination; however, it can not be
used as an alternate. Keep in mind, alternate airports are only required in
certain weather conditions.


Or if you are filing to an airport without an approach.

Chuck
  #6  
Old December 24th 03, 09:16 PM
Michael
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"smf" wrote
What exactly does the /A\na on approach plates mean. I know it says
Alternate minimums not authorized. Does it mean the airport can't be used as
an alternate?


Not quite. It means that approach can't be used in determining
alternate minima for that airport.

There are three kinds of alternate minima (see 91.169c):
For a precision approach, 600-2 unless otherwise noted
For a non-precision approach, 800-2 unless otherwise noted
If no approach exists, weather conditions that allow descent from the
MEA, approach, and landing under basic VFR.

Under these rules, ANY airport (even one with no published approaches)
can be used as an alternate if the weather is good enough, and the
determination of how good the weather has to be (alternate minima for
the airport) is made based on what approaches are available.

The /A\na means that the specified approach is not to be used as a
factor in the determination. It doesn't mean the airport can't be
used as an alternate - other approaches at the same airport may not
have the same restriction, and in any case even if all approaches are
so restricted the airport can still be used as an alternate if the
weather is good enough.

I have actually seen one airport served by half a dozen approaches,
including an ILS, where all the approaches were noted /A\na except one
NDB approach. This means that rather than using the typical minima
for an ILS-equipped airport (600-2) the more restrictive non-precision
minima (800-2) must be used. Note that this does not preclude the use
of the ILS approach to get into the airport should you need to go
there.

Michael
  #8  
Old December 24th 03, 09:47 PM
ArtP
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On Wed, 24 Dec 2003 10:24:31 -0800, "Tarver Engineering"
wrote:

Isn't the GPS rule only true if your primary destination used a GPS
approach?


GPS can't be used for an alternate regardless of the type of approach
at the primary.
  #9  
Old December 29th 03, 03:52 PM
Michael
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Roy Smith wrote
I have actually seen one airport served by half a dozen approaches,
including an ILS, where all the approaches were noted /A\na except one
NDB approach.


Any idea why?

My understanding was that an approach got the /A\ thingie if the navaids
required to fly it were not monitored.


That sort of makes sense - the NDB probably had remote monitoring
because it was part of an airway once, long ago. I think the last of
the NDB airways in the US were decomissioned a couple years ago,
though.

If you look up the alternate mins for KCLL (College Station, TX) you
will see that the ILS and LOC BC go NA when the tower closes, but the
VOR approach doesn't. I suspect this is because CLL VORTAC must be
remotely monitored because it forms the basis of multiple STAR's
serving Houston and Dallas, whereas the ILS transmitter is probably
only monitored in the tower cab.

Michael
  #10  
Old December 29th 03, 07:59 PM
Scott Skylane
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Michael wrote:

Roy Smith wrote

I have actually seen one airport served by half a dozen approaches,
including an ILS, where all the approaches were noted /A\na except one
NDB approach.


Any idea why?

My understanding was that an approach got the /A\ thingie if the navaids
required to fly it were not monitored.



That sort of makes sense - the NDB probably had remote monitoring
because it was part of an airway once, long ago. I think the last of
the NDB airways in the US were decomissioned a couple years ago,
though.

/snip/

Not sure about the Lower 48, but there are still plenty of Low Frequency
airways in Alaska. In fact, quite a few of our NDB's have DME
associated with them.

Anyone know of any colored airways in the ConUS?

Happy Flying!
Scott Skylane

 




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