Originally Posted by
percysmith
If check in airline can check through on separate tickets, I suppose they can validate onward ticket numbers on other airlines for bag tag interlining?
But BA has abolished check through on other airlines for its check ins, their agents might no longer trained to perform this.
Through-bag tagging uses a different messaging 'channel' from IATCI (Inter-Airline Through Check-In), and to my knowledge that methodology doesn't provide a way to confirm that an e-ticket exists for the onward connection. What the bag through-check-in does is to send a message, almost 'blindly', to the other airline that says "Hey there other airline, this bag here needs to come to you". There's no answer back as far as I can remember, and it relies on the second airline picking up the bag at the end of the first leg of the journey.
IATCI is different; here a call is made from the first airline to the second, and the second responds with the seatmap availability and so on. However, an agreement must exist between airlines, and it all has to be on a single PNR (or linked PNRs); as a BA check-in agent I can't, for instance, check-in somebody on Air Mauritius if there's no agreement between the two carriers and the booking isn't done on a single PNR.