Hi. I'm studying about 121 alternate airport minimums : When an alternate needs to be filed and the minimums required for the alternate. This will be applied for a regional carrier (ie Eagle or Colgan).

From what I've found, if it is a domestic 121 flight, the standard 1,2,3 rule works to determine if an alternate is needed. Does this apply for regional airlines like Colgan or Eagle? I read some items about 1500 feet above circling mins.

And for the alternate, should the "Add 400 and 1 SM Vis if 1 Nav aid" or "Add 200 and 1/2 SM Vis if 2 Navs" be used?

Anyone have any real world experience?