mistarose

THIS IS WHAT I BELIEVE TO BE CORRECT, I am posting this to check it against everyone's knowledge. Please inform me if there is anything that is incorrect or could be said better. Also, I understand that once you get hired its the Ops Specs that matter, but this 121 knowledge is for an interview I am preparing for and Ops Specs are unavailable.



Do we need a takeoff alternate?

Yes, if the visibility is below the lowest available approach's minimum prescribed visibility at the departure airport.

Guidelines for choosing takeoff alternate:

Can be no more than 1 hour away from the departure airport at single-engine cruising speed in still air.

The WX their must be at or above the the published alternate minimums for the takeoff alternate airport.



Do we need a destination alternate?

Yes, if between 1 hour before and 1 hour after the ETA at that airport, the forecast conditions are below 2,000 feet ceiling and/or 3 sm visibility.

Requirements for choosing destination alternate:

The WX their must be at or above the the published alternate minimums for the takeoff alternate airport.

Additional Dest. Alt. Requirement: If the weather at the destination and destination alternate are "marginal" you must select an additional destination alternate with the same guidelines for choosing an alternate.



Fuel:

Fly to destination and then to furthest alternate and then for 45 minutes at normal cruise.

flynavyj

all looks good to me...once hired, you'll learn the tricks of deriving alternate minimums as opposed to using the published minimums on the Jepp Plates. but these will also be equipped in your Ops Spec.

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rsmithadx

This is advise from an active dispatcher....

Since all 121 carriers use Ops Specs I think you would be safe instead of saying "published alternate minimums".....you would be safe saying"derived alternate minimums"

I think you will sound more professional.

dojetdriver

Along the same lines, as far as the TO alternate goes;

Interviewer: "When do you need a TO alternate?"

You: "Whenever the vis is below the lowest available approach minimums prescribed at the departure airport."

Interview: "OK, so the vis is below CATI mins but above CATII mins. We are CATII qualified, do we need a TO alternate?

You: "uh, um, well........."

It has to be at or above the lowest CATI minimum for an approach in use at that airport. If it was at CATII mins and you blasted off and had a component failure that affected your CATII capability, you would not be able to get back in using a CATII approach. An example would be a bird strike that took out one of the pitot/static components or a LOC/GS antennae when 2 are required for a CATII approach.

So, when do you need a TO alternate? When the vis is below the lowest CATI minimum for an approach in use.

mistarose

Thanks for the confirmation everyone - feeling more confident now. I'll remember everyone's advice.