The take-off alternate shall be within the following distance from the departure aerodrome:
Aeroplanes with 2 power units
Not more than the distance equivalent to a flight time of one hour at the single-engine cruise speed.
Aeroplanes with 3 or more power units
Not more than the distance equivalent to a flight time of two hours at the one-engine inoperative cruise speed.
Typically, this is 250 n.m. for the 737/757 and 400 n.m. for the DC-10.
