Originally Posted by
YYC009
1) It depends if 'OSS' is marked on the boarding pass. If the previous carrier doesn't participate in the program, then there is no IT infrastructure to print 'OSS' on the downline boarding passes.
2) Definitely possible. It is not a foolproof system. As others mention, there is nothing stopping a PEK-YYZ passenger who is not OSS eligible from handing something off to a DEN-YYZ passenger who is OSS eligible on the way to the Customs Hall.
Earlier in the month I flew BJX (Leon, MX.)-IAH-YUL-YHZ, first flight with UA, connecting to AC. UA printed boarding passes did not say OSS on them. Upon arrival in Houston I had AC reprint my boarding passes, and the AC printed boarding pass to YUL had OSS. Was a great surprise in YUL to straight from customs into the domestic/intl gate area, as when I flew through in the summer OSS hadn't been implemented.