121 Regs- Alternate Mins.
10-31-2006 | 09:24 AM
#1
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From: CRJ
121 Regs- Alternate Mins.
Could some one clarify the 121 regs referring to destination alternates? When are they required...is it the old 123 Rule or are they always required...and what should the weather be at the alternate at the time of arrival?
Any help would be great, thanks.
jdr
Any help would be great, thanks.
jdr
10-31-2006 | 09:30 AM
#2
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From: Engines Turn or People Swim
Basically 123 applies for starters, but there are airline-specific formulas for determining alternate mins, and secondary alternates.
Also, domestic, flag, and supplemental operations can have different rules.
10-31-2006 | 09:32 AM
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From: Still Swinging props!
Ooooh, he didn't just ask that, did he? LOL.
There are several 'get out of jail free' cards that 121's use to get in. They are exceptions to the regs that are listed in their ops specs, so that's why you couldn't find them. If you do a search on "marginal conditions" and Exception 3585, you'll find quite an extensive list of requirements. The gist is that you can get in to an airport with less than 'normal' mins, if you have certain conditions met and use not just an alternate airport destination, but a second alternate destination as well.
I'll save you my lame attempt at describing the rules, it'd be like me trying to describe the governor on an autofeathering turboprop! That's supposed to be funny. Sorry.
There are several 'get out of jail free' cards that 121's use to get in. They are exceptions to the regs that are listed in their ops specs, so that's why you couldn't find them. If you do a search on "marginal conditions" and Exception 3585, you'll find quite an extensive list of requirements. The gist is that you can get in to an airport with less than 'normal' mins, if you have certain conditions met and use not just an alternate airport destination, but a second alternate destination as well.
I'll save you my lame attempt at describing the rules, it'd be like me trying to describe the governor on an autofeathering turboprop! That's supposed to be funny. Sorry.
10-31-2006 | 09:34 AM
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From: AA A320
121 Domestic
1 hour before and after ETA: 3 miles vis and 2000' ceilings.
121 Supplemental
Must always file an alternate.
The required alternate whether is most likely going to be company specific.
In my case, if the airport has 1 nav aid, then you have to add 400' and 1 mile to the published mins; thus creating "derived" minimums. If the airport has 2 nav aids, then you have to add 200' and 1/2 mile to the published minimums.
Also, keep in mind that there are other alternates besides destination. There are also takeoff, wind, braking, and driftdown.
1 hour before and after ETA: 3 miles vis and 2000' ceilings.
121 Supplemental
Must always file an alternate.
The required alternate whether is most likely going to be company specific.
In my case, if the airport has 1 nav aid, then you have to add 400' and 1 mile to the published mins; thus creating "derived" minimums. If the airport has 2 nav aids, then you have to add 200' and 1/2 mile to the published minimums.
Also, keep in mind that there are other alternates besides destination. There are also takeoff, wind, braking, and driftdown.
11-08-2006 | 02:22 PM
#6
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From: EMB CA
121 Domestic
The required alternate whether is most likely going to be company specific.
In my case, if the airport has 1 nav aid, then you have to add 400' and 1 mile to the published mins; thus creating "derived" minimums. If the airport has 2 nav aids, then you have to add 200' and 1/2 mile to the published minimums.
Also, keep in mind that there are other alternates besides destination. There are also takeoff, wind, braking, and driftdown.
The required alternate whether is most likely going to be company specific.
In my case, if the airport has 1 nav aid, then you have to add 400' and 1 mile to the published mins; thus creating "derived" minimums. If the airport has 2 nav aids, then you have to add 200' and 1/2 mile to the published minimums.
Also, keep in mind that there are other alternates besides destination. There are also takeoff, wind, braking, and driftdown.
Here's an example: KRIC 121 ops
If you look on the 10-9A page, it has at the bottom a list of weather minimums for filing it as an alternate. The lowest is 600-2. If I were to use the derived minimums for that airport using ILS 2 & 34, I can get 400-1. So which minimums are the ones you use for filing it as an alternate?
Thanks for the help.
11-08-2006 | 02:40 PM
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From: AA A320
You have to abide by your company's ops specs. In some cases, yes, they will be more restrictive than the standard part 91 requirements.. but there is usually a way around that.
Most companies have exemptions that allow them to dispatch aircraft under IFR to airports that are forecast to be below otherwise authorized minimums at the flight's ETA.
Most companies have exemptions that allow them to dispatch aircraft under IFR to airports that are forecast to be below otherwise authorized minimums at the flight's ETA.
11-08-2006 | 05:05 PM
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From: 737 Captain
Here are my basic guidelines in determining alternates:
If your destination weather sucks, plan an alternate where the weather is good, or some place you really want to go. Your dispatcher will do all the legal-eze filing and forecasting but you as the PIC should look closely, based on your experience and gut instinct, to make your decisions. Just because you can legally do it doesn't mean you should. I routinely get filed with alternate airports that I would have no intention of going to. We file that way for convenience and efficiency but in reality I will likely have other ideas in case we really need to divert. As long as I have enough fuel and resources to get somewhere I want to go safely, I am good with it. You can look up the specifics of your regs over the first round at your chosen alternate.
If your destination weather sucks, plan an alternate where the weather is good, or some place you really want to go. Your dispatcher will do all the legal-eze filing and forecasting but you as the PIC should look closely, based on your experience and gut instinct, to make your decisions. Just because you can legally do it doesn't mean you should. I routinely get filed with alternate airports that I would have no intention of going to. We file that way for convenience and efficiency but in reality I will likely have other ideas in case we really need to divert. As long as I have enough fuel and resources to get somewhere I want to go safely, I am good with it. You can look up the specifics of your regs over the first round at your chosen alternate.
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