probably DL or UA.not tried usair yet as i live in den and pit not the easiest to get to.suppose it all depends on your agreements also.for ex.last carrier i worked at we couldn't get on AA or CO internationally.have been on a co flight int.but was stuck and the crew let me on ,in a pinch.bless 'em!usasir sounds easy for you,i think.anyway always have an id90 or two sitting in your bag for a carrier you cannot jump on.for the uk i used virgin as they had a ZED fare agreement with us,and the ticket was cheap.good for 90 days and fully refundable ,thru your travel/pass bureau ,for whatever you don't use...so good escape plan if it all falls apart.i found in the EU all the us carrier ground staff,for most part knew of jumpseaters.asia a little different.also:much easier to wait the extra time there, in line, to speak to somebody/customer service when you arrive,and find out any rules for travelling home, than getting on the phone the day before departure.....!a smile and good attitude goes a long way ,nonetheless!