Takeoff Alternates

[stensonb]

I'm almost embarrassed to ask the question but I've got to be missing something...

In looking at the NACO Alternate Minimums, I've noticed that some airports have alternates minimums listed for specific approaches...WTF?

My understanding was that I file an alternate when required (3-2-1 rule for Part 91) and I have to have the 800-2 or 600-1 for the alternate I file when I expect to get there...unless its listed in the Alternate Minimums section...then I have to have that specified ceiling and visibility minimum...These conditions are *not* tied to the specific approach I plan on using at the alternate airport...

Why then, are alternate minimums listed for different approaches? What am I missing? Is it a takeoff minimum requirement for 121/135 stuff? That is, if the alternate minimum is listed for RNAV (GPS) Rwy 5, and I'm a 121/135 operator, I have to have the listed alternate minimums in order to takeoff on Rwy 5....but then, why are there Takeoff Minimums listed as well?

So confused...

[Ian J]

Originally Posted by stensonb

I'm almost embarrassed to ask the question but I've got to be missing something...

In looking at the NACO Alternate Minimums, I've noticed that some airports have alternates minimums listed for specific approaches...WTF?

My understanding was that I file an alternate when required (3-2-1 rule for Part 91) and I have to have the 800-2 or 600-1 for the alternate I file when I expect to get there...unless its listed in the Alternate Minimums section...then I have to have that specified ceiling and visibility minimum...These conditions are *not* tied to the specific approach I plan on using at the alternate airport...

Nope, but if there is that "A" on the approach plate then they might be.

Why then, are alternate minimums listed for different approaches? What am I missing?

Because of TERPS criteria. Think about why they would need to list alternate minimums. Most likely because something (an obstruction or terrain) is getting in the way of the approach.

Is it a takeoff minimum requirement for 121/135 stuff? That is, if the alternate minimum is listed for RNAV (GPS) Rwy 5, and I'm a 121/135 operator, I have to have the listed alternate minimums in order to takeoff on Rwy 5....but then, why are there Takeoff Minimums listed as well?

So confused...

No - there are a couple types of takeoff mins. As you probably know, there are none for part 91 (unless denoted by the black "T" on the plate), and there are some for 135/121 ops listed in the FAR. These T/O mins are almost always reduced per the operator's OPSPECS. No matter what though, any t/o mins listed on the approach plate are controlling. Then there is the question of a take off alternate which really doesn't apply to the discussion.

Takeoff mins denoted by the "T" on the approach plates dictate either alternate take off mins or an obstacle departure procedure. These have nothing to do with alternate mins as posed in you original question.

[B767Driver]

Originally Posted by stensonb

I'm almost embarrassed to ask the question but I've got to be missing something...

In looking at the NACO Alternate Minimums, I've noticed that some airports have alternates minimums listed for specific approaches...WTF?

My understanding was that I file an alternate when required (3-2-1 rule for Part 91) and I have to have the 800-2 or 600-1 for the alternate I file when I expect to get there...unless its listed in the Alternate Minimums section...then I have to have that specified ceiling and visibility minimum...These conditions are *not* tied to the specific approach I plan on using at the alternate airport...

Why then, are alternate minimums listed for different approaches? What am I missing? Is it a takeoff minimum requirement for 121/135 stuff? That is, if the alternate minimum is listed for RNAV (GPS) Rwy 5, and I'm a 121/135 operator, I have to have the listed alternate minimums in order to takeoff on Rwy 5....but then, why are there Takeoff Minimums listed as well?

So confused...

A takeoff alternate is entirely separate and the terms will be spelled out in the air carrier's operations specifications (a separate set of "regs", if you will, for air carriers).

What you are looking at is the approaches that can support your alternate weather requirements. Let's say all of the ILS's are notamed out of service today...then you cannot use the alternate minimums column listed for those approaches.

Therefore, you must find an approach that is fully operable at your alternate airport...look what column it falls under...and that's the alternate wx minimums for you.

Another example where an approach would be unusable...let's say that there is only one ILS to runway 36. The winds are from the south at 25 knots. Your alternate weather minimums will probably increase because this approach will not be suitable today. You should plan on using a non-prec approach from to the south runway.

Are you working with a CFI? If not PM if you are still not clear on the issue. I think you are confusing some issues...but should be easily cleared up.

[ghogue]

Originally Posted by stensonb

My understanding was that I file an alternate when required (3-2-1 rule for Part 91) and I have to have the 800-2 or 600-1 for the alternate I file when I expect to get there...unless its listed in the Alternate Minimums section...then I have to have that specified ceiling and visibility minimum...These conditions are *not* tied to the specific approach I plan on using at the alternate airport...

Alternate approach minimums are always tied to an approach (unless you are using an airport without an instrument approach as your alternate). BTW, it's 600-2 for precision approaches.

[stensonb]

Originally Posted by B767Driver

Therefore, you must find an approach that is fully operable at your alternate airport...look what column it falls under...and that's the alternate wx minimums for you.

What do you mean "what column it falls under"?

Let me be a little more concrete. Pullman, Washington (PUW) has RNAV (GPS) approaches to Rwy 5 and 23, VOR Rwy 5, and VOR/DME-A. The plates for RNAV Rwy 23, VOR Rwy 5, and VOR/DME-A do not have the "A" symbol...indicating they all have standard alternate minimums...

The RNAV Rwy 5 has the "A" symbol...looking at the Alternate Minimums section (Section E of the NACO charts), it has the following:

PULLMAN/MOSCOW,WA
PULLMAN/MOSCOW MUNI ............ RNAV (GPS) Rwy 5,800-2¼

So, am I to assume that if the winds favor GPS Rwy 5 approach, I must have 800-2¼ to file as an alternate...but if I have 800-2 I can plan on using the VOR/DME-A, because it has standard alternate minimums...

I guess I'm just bewildered as to why I could have a valid alternate based on one approach to an airport, and not based on another...especially when the forecasted winds (the primary reason for one approach over another) are not identified as defining criteria for alternate selection.

[stensonb]

Originally Posted by ghogue

Alternate approach minimums are always tied to an approach (unless you are using an airport without an instrument approach as your alternate). BTW, it's 600-2 for precision approaches.

Typo, thanks.

[stensonb]

Originally Posted by ghogue

Alternate approach minimums are always tied to an approach (unless you are using an airport without an instrument approach as your alternate). BTW, it's 600-2 for precision approaches.

Well, sort of. Not to get too technical, but as long as the airport has a precision approach, I can file it if the weather is expected to be 600-2 even if the winds favor a nonprecision approach...

...or can I?

There's a legal answer and a practical answer, I realize...

[Soul Brotha']

Originally Posted by B767Driver

A takeoff alternate is entirely separate and the terms will be spelled out in the air carrier's operations specifications (a separate set of "regs", if you will, for air carriers).

What you are looking at is the approaches that can support your alternate weather requirements. Let's say all of the ILS's are notamed out of service today...then you cannot use the alternate minimums column listed for those approaches.

Therefore, you must find an approach that is fully operable at your alternate airport...look what column it falls under...and that's the alternate wx minimums for you.

Another example where an approach would be unusable...let's say that there is only one ILS to runway 36. The winds are from the south at 25 knots. Your alternate weather minimums will probably increase because this approach will not be suitable today. You should plan on using a non-prec approach from to the south runway.

Are you working with a CFI? If not PM if you are still not clear on the issue. I think you are confusing some issues...but should be easily cleared up.

Ops Specs vary from company to company.

[Ian J]

Originally Posted by stensonb

Well, sort of. Not to get too technical, but as long as the airport has a precision approach, I can file it if the weather is expected to be 600-2 even if the winds favor a nonprecision approach...

...or can I?

There's a legal answer and a practical answer, I realize...

Assuming there aren't any alternate minimums listed, absolutely.

[FlySmiley]

The reason you file an alternate in the first place is because there is a "chance" you will not get in to your destination right?

So why would you want your plan B to be setup for failure from the start? In the example of a NOTAMed glideslope it is pretty obvious you aren't going to shoot that ILS. For this reason if you cannot plan on being able to use the ILS, the minimums to file that airport as an alternate would need to increase. Likewise, if there is terrain or another factor that increases the normal approach minimums, chances are the minimums to use that airport as an alternate also increase (non-standard).

On the practical application end, the filed alternate simply satisfies a legal requirement that you will not only be able to land, but more importantly, have the fuel to do so. Remember, you are not required or even necessarily expected (generally speaking) to divert to your filed alternate if you are unable to land at your original destination.

If the winds are simply favoring one approach over another that is fine, however, if the winds would cause you to exceed a limitation by attempting the approach (i.e. tailwind landing limits, etc.) then IMO you would need to exclude that approaches availability when determining the alternate weather minimums.

[mikecweb]

Originally Posted by FlySmiley

If the winds are simply favoring one approach over another that is fine, however, if the winds would cause you to exceed a limitation by attempting the approach (i.e. tailwind landing limits, etc.) then IMO you would need to exclude that approaches availability when determining the alternate weather minimums.

Is there any freight dawg left in you?

It's been a long time btw. We need to catch up, drink some beers and chase women.

[FlySmiley]

PM sent Mike

Sadly, the hard part is convincing these sissy captains that handflying an approach is smoother and that the flight director just gets in the way.