Originally Posted by
singal3
They will not be able to make a $100 change currently because "A" "I" "D" "C" inventory (depending on which fare you booked) is zeroed out for Ex-Vietnam routes to the US (at least the ones I checked).
Oh tricky tricky, my flights are J A A J, so they could marry the segments so that A is always 0 when connecting from Vietnam to the US (and vice versa) to disallow changes without violating the fare rules. Alternatively, they may just never open A again on those flights that are sold out of A now, also disallowing changes unless you happen to find a day where A isn't 0.
I did find one day at least where the former is the case - 2/14/19 has A1 on 846 to JFK; however, if you search for DAD/HAN/SGN to JFK, A0 shows. Whether this is typical behavior by CX (I checked BKK-JFK and 846 is A1, so I am guessing they married the segments for Vietnam) or a way to limit changes is unknown to me.