For your domestic flight, the 500 mile minimum per segment applies so a flight of 280 miles is a base 500 miles.
500 + 10%Cos (50) + 125% 75K (625) = 1175
AS' customer service has been claiming for several months now that the website is wrong and that domestic Japan J is only 10% CoS, however in all this time the chart hasn't been updated nor has AS ever had a separate domestic chart like AA does. My personal opinion is AS needs to honor their published chart or fix it if it's wrong.
Call in and request a supervisor for escalation?