These changes apparently have to do with the fact that NW didn't have the B752 aircraft available to operate the planned AMS EWR AMS as it prefers to use that capacity for a second daily DTW FRA flight. As a result, KLM will operate the EWR rotation as KL657/658 with A332, which has necessitated taking the A332 away from the newly introduced KL645/646 early morning rotation. The third daily JFK rotation is now planned to start for the winter schedule.