Basically, to qualify as an alternate airport, the alternate must have certain forecast weather conditions (600-2 for precision approach, 800-2 for non-precision.) These are the alternate minimums.
People Also Ask
LNAV approaches are less precise (556m lateral limit) and therefore usually do not allow the pilot to descend to as low an altitude above the runway.
Not more than one hour from the departure airport at normal cruising speed in still air with one engine inoperative. (2) Aircraft having three or more engines. Not more than two hours from the departure airport at normal cruising speed in still air with one engine inoperative.
In aviation medicine, the 1% rule is a risk threshold that is applied to the medical fitness of pilots. The 1% rule states that a 1% per annum risk (See also risk management) of medical incapacitation is the threshold between acceptable and unacceptable.