How to add Precheck to Delta? There are two ways to add TSA PreCheck to your Delta Airlines account: During the booking process: When you are booking a flight on Delta's website or app, you will be asked to enter your Known Traveler Number (KTN). This is your TSA PreCheck number. If you don't have a KTN yet, you can apply for it on the TSA website. After booking: If you have already booked your flight and you have a KTN, you can add it to your Delta account by following these steps: Go to the Delta website and log in to your account. Click on your name in the top right corner of the page and select "Profile." Click on "Secure Travel Info." Enter your KTN in the "Known Traveler #" field. Click on "Save."