You cannot jumpseat internationaly under the CASS program. I do not think FedEx will allow you to jumpseat internationaly whether you are in the CASS program or not [I think it has to do with TSA rules, not the pilots]. Most other airlines will allow you to jumpseat internationaly if you pay the taxes out and in, and there is a seat in the back. However, most limit the J/S'rs to however many J/S's are in the cockpit [i.e. B767 = 2 total J/S'rs]. I know AA and CAL require an international reciprocol agreement [i.e. your carrier must be able to reciprocate internationaly]. Last, you want to check in at least 2 hrs prior to your scheduled departure on flight returning to the United States from foreign countries [non US territories]. Good Luck