2nd Alternate Rule (Ops Specs)

[FurloughedAgain]

Could use a little bit of help regarding plain-language description of the "2nd alternate" rule in company ops specs.

The question I'm trying to answer (without digging to big of a hole) is: "What is a second alternate?"

Here's what I have so far.

2nd Alternate is required in 3 situations.

1. If the destination visibility in the conditional words (prob, tempo, becmg) is forecast to be 1/2 the required visibility for the approach you may still dispatch provided you have a second alternate.

2. Look at your first alternate. The required ceiling AND visibility in the main body of the TAF must meet derived minimums OR (if they dont) the ceiling and visibility in the CONDITIONAL words may be 1/2 the derived alternate ceiling and visibility if a second alternate is filed.

3. Marginal Rule: If the destination ceiling OR vis is forecast to be at approach minimums when you arrive.... AND if the first alternate is forecast to be at derived mimums when you arrive...then you need a second alternate.

NOTE: A second alternate requires that both ceiling and visibility in both the main body and conditional words of the TAF MUST be above derived minimums. (may NOT be reduced)

 

[SkywayFO]

Even Simpler.

There are 2 times a second alt is Requiered:

1) Marginal Weather ( OR And OR Rule)

If Destination weather is:
At or Below Ceiling
"OR"
At Vis.

"AND"

1st Alt is:

At Ceiling
"OR"
At Vis.
Required for use as an Alternate

Dirived From 141 and 22 &1/2 rules.
141
1 approach add 400 and 1 to mins.
22 & 1/2
2 suitable approaches add 200 and 1/2 to the highest of the Ceilings and the highest vis. of the 2 approaches, could be vis from one and ceiling from the other.

2) if 3585 is used you must have a second alternate.

In eaither case the 2nd Alt must be golden (ie. above dirived mins.)

That is my two cents this little bite got me through 3 oral at 2 airlines.

Good Luck!!

 

[atldc9]

Under FAR 121, there are specifically 2 times when a second alternate is required. There may be others that I am missing, but the following are very clear cut.

1. 121.619 Alternate airport for destination: IFR or over-the-top: Domestic operations.

(a) No person may dispatch an airplane under IFR or over-the-top unless he lists at least one alternate airport for each destination airport in the dispatch release. When the weather conditions forecast for the destination and first alternate airport are marginal at least one additional alternate must be designated.

2. When dispatching under Exemption 3585, one of the conditions of using the exemption is to list a second alternate. This is the condition where the conditional language in your destination's forecast is below landing min's, but not less then half of that required.

Note that these instances are for destination alternates, a Takeoff alternate may be required if your departure airport is below landing minimums, but still legal for takeoff. In that case you could need 2 alternates, one for takeoff, and one required if the wx at your destination was below that required in 121.619

 

[DCitrus9]

marginal weather:

my understanding, according to FAA approved company manual, of marginal weather requiring a second alternate consists of:

destination-vis at minimums AND
alternate- visibility AND ceiling at minimums (using 200-1/2 or 400-1 rule for alternate)

The marginal rule rarely(never?) comes into play. Far more often you need a second alternate due to 3585
This is slightly different than skywayFO's definition. How does everyone else operate? I seem to remember my commuter being the same as I listed above, but that was a while ago...
I'm just curious if the FAA is allowing that much disparity in the dispatching, or if there is a misunderstanding in the interpretation.

 

[freightdogfred]

I think the disparity lies in the fact that the language of the exemption varies among certificates.......

 

[tarp]

Huh?

I'm with Atldc9's rather compact definition from the FAR's which is the model for all of our Ops Specs.

1.) When is a 2nd alternate required?

Ans.) It is required if the weather is marginal at the destination AND the (first alternate) -or- when dispatched under Exemption 3585(*see note below).

2.) What is the definition of marginal?

Ans.) "Marginal" weather exists when the ceilings AND/OR visibilities are at or below the minimums required for approach and landing.

3.) How are minimums defined?

Ans.) Minimums for operations are defined as follows:
For a destination airport, the minimums are published on NOS or Jepessen approach plates for the services available at the time of landing. (Use caution: Winds, runway closures and NOTAMS may effect services available)
For Alternate Airports,
Method 1 - the operator may chose a single instrument approach to an airport and add 400ft to the ceiling and 1 mile to the visibility (400-1).
Method 2 - at an airport serviced by multiple approach facilities, the operator may chose 2 approaches as long as those approaches do NOT share the same identifier for the same runway. In this circumstance, add 200ft to the highest of the two ceiling values selected and 1/2 (one-half) mile to the highest of the two visibility values selected. (200-1/2).

4.) What is Exemption 3585?

Ans.) 3585 is an exemption for approved operators that allows a flight to be dispatched when a "conditional" statement in a weather forecast would be disqualifying under certain provisions. The "main body" of the forecast must ALWAYS be at or above minimums. However, conditional statements such as "probability", "temporarily" and "becoming" may be discounted. For the destination airport, in the conditional statement, only visibility is controlling and may be reduced to a value of 1/2 the Landing Minimums. For the First Alternate, ceiling and visibility are controlling and may be reduced to a value of 1/2 the alternate minimums (as calcualted thru Method1 and Method2). For the second alternate, there is no relief to a conditional statement and it must be at or above the alternate minimums (using Meth1/Meth2).

So there you have it.

Do you have marginal weather? No. then a second alternate is not required. (Note: if you read Exemtion 3585 carefully, there is no need to even use 3585 unless marginal conditions already exist. However, some dispatchers do not understand these regulations either and use 3585 which automatically requires them to state a second alternate.)

How do you know if you have marginal weather?
Read the Jepp plates and apply to destination or use Method1 / Method2 to use for the alternate(s). Compare this to the forecasts for your destination and alternate at the time of arrival.

And finally, how do you know you need a first alternate?
Part 91 - 1,2,3 rule. For a period of one hour before to one hour after your arrival time at the destination, the weather must be greater than 2000 ft ceiling and 3 miles viz or you are required to list an alternate.

Ain't it simple.

 

[MONKEY]

Those who responded to this thread, please review your 3585. Call dispatch or your chief pilot untill you understand it. The guy who posted that you are required to have an alt. with a ceiling of 2000' please look at that. 2000' does not require an alt. Not trying to be a jerk with my first post, but 3585 is something that needs to be understood.

 

[DC9stick]

"Those who responded to this thread, please review your 3585. Call dispatch or your chief pilot untill you understand it. The guy who posted that you are required to have an alt. with a ceiling of 2000' please look at that. 2000' does not require an alt. Not trying to be a jerk with my first post, but 3585 is something that needs to be understood."

I read and reread all these posts and could not find what you were talking about. The only coment made about 2000' was that if the wx was below 2000' you DO need an alternate.

I'm no golden boy on this board but at least I read the posts before I respond!!! Before you Monkey around here maybe you should too!

 

[MONKEY]

the weather must be greater than 2000 ft ceiling and 3 miles viz or you are required to list an alternate.

In the post you said "must be greater than 2000 ft" or you need an alt. Greater being the wrong word. If you have a ceiling of 2000 ft that does not require an alt. Vis of 3 miles does not require an alt. You may think I am spliting hairs, but it is you who is misspoken. I am not trying to be cocky with an I know more than you attitude, but these things need to be understood.

 

[tarp]

Mea culpa.

"Greater than" should be changed to "not less than".

I hope I don't burn in he11 for that one.

PS, "until" is spelled with one "l", but we're all human aren't we.