Upvote:2
If you have NEXUS, SENTRI or Global Entry, the number is on the back of your card and starts with 98.
If you're a member of TSA Pre and forget your number, you can look it up via this website.
Upvote:2
Log into your account on aa.com, click on “Hello, name” and “your account”. There, click “information and password” and then scroll down to the “secure traveler” section. You’ll find your number in the “known traveler number” field.