Papacharlie,

BlueSkiesAhead I think answered the question you were asking (not trying to offend the others-truly). The NAVAID needs to be monitored. I wish I had a reference to give you, but I'm serving in a sandy place shall we say, away from most of my flying books for the time being.

I remember being confused by this too, and my CFII didn't address this for me. So look in the upper left hand corner of your approach plate, and if there is an A inside the black triangle with an N/A it means that approach can't be used as an alternate at all-good wx forecasted or not.

You'd be surprised at some of the places that are unmonitored. A common airport I fly in and out of is Class D with Regional aircarrier service, but all it's approaches are considered 'unmonitored' so no filing these approaches as an alternate.

First make sure there is no N/A for that approach, then think about the weather mins e.g., 800-2 or 600-2 (or any nonstandard mins), how the winds will make or break a given approach, and having an approach other than just GPS.

Does that help?