Can I apply my TSA Precheck Known Traveler Number to my Delta ticket after I have purchased them (but obviously before obtaining a boarding pass). I used to have precheck, obtained as a government employee. My Known Traveler Number was my CAC number on the back of my government ID card. I have since retired, so my CAC is no longer valid. I checked and it appeared that my TSA precheck KTN was also no longer valid. So I applied for a new one, as a civilian. It is still being processed. Can I go ahead and purchase tickets now for a flight in a month or two, then add the KTN information to them after it is complete? If so, how would I do that?... Just by calling Delta customer service? Thanks.