Originally Posted by
FallenPlat
The harder part, though, is attaching a known traveler number to the reservation -- full correct names match, everything -- the day before a flight. I'm not sure exactly how many hours of advance notice the system needs for the KTN to work on an already existing reservation. (Once you're up and running, the KTN is attached to your airline frequent flier profile (something the you have to do manually, by the way) and then auto-populates all your new reservations going forward.)
Maybe someone else knows the answer to that question?
If the Secure Flight information in your PNR matches your GE data then adding a KTN to the PNR seems to work very soon afterwards. I did an ORD-FAR-ORD out and back to hit my 50th state last fall and spent the 4 hour layover visiting the Fargo Air Museum. I used BA Avios and was thus ticketed through BA which doesn't store any KTN information in their system. I then updated my AA PNR online to add my GE KTN. However, there was a minor schedule change and I'm guessing that somehow during the interaction between the BA and AA systems my KTN got wiped in the AA system because I didn't get TSA PreCheck on the outbound. While sitting at the outbound gate I called AA and had my KTN added back. When I used a kiosk at FAR to get my boarding pass it had TSA Pre.