How does FAA determine Alternate is not authorized?

[FlyingToIST]

A good instrument student asked me how FAA determines an alternate cannot be authorized for an airport; and i came up with 'terrain, nav facilities and airspace' like considerations.
Is there a reference where i can refer him to ?

 

[CA1900]

From the front of the NACO approach chart booklet:

"NA - means alternate minimums not authorized due to unmonitored facility or absence of weather reporting service."


Hope that helps.

 

[Amish RakeFight]

approach based on an unmonitored facility