Make sure you have your Known Traveler Number (KTN) and a valid TSA PreCheck membership before adding TSA PreCheck to your Japan Airlines flight. How To Add TSA Precheck To Japan Airlines Go to the “Manage Booking” part of the Japan Airlines website by logging in. Find your reservation and fill in the KTN field available. As an alternative, you can manually adjust your booking by giving Japan Airlines’ customer service a call. To take advantage of faster security screening at U.S. airports, make sure your KTN is added well in advance of your trip. Recall that TSA PreCheck is only valid for travel from American airports.