The unique identification number assigned to you by the TSA when you are approved for TSA PreCheck or Global Entry. You must enter this number into every single flight reservation you make to receive expedited screening.

💡The Flight Expert Take: The Exact Match Dilemma
The most common reason PreCheck fails to appear on a boarding pass is a name mismatch. Your ticket name must match your KTN registration character-for-character.

If your KTN is under “Michael” but you book your ticket as “Mike,” the secure flight system will reject it, and you will be stuck in the slow lane. If your Global Entry account includes your middle name, your flight ticket must also include it.

A leg is the physical travel between two airports, consisting of one takeoff and one landing. It is the most basic building block of any flight itinerary. While a nonstop flight only has one leg, a direct flight can have multiple legs if the plane stops to refuel or pick up passengers at an intermediate airport before continuing to the final destination.

💡 THE FLIGHT EXPERT TAKE: Getting a “Leg” Up
Understanding legs will help you spot hidden stops in what look like simple routes. Every additional leg you add to a trip is another chance for a mechanical delay or a weight limit issue to crop up. When you’re looking at a direct flight, remember you’re signing up for multiple legs, which means extra time on the tarmac even if you don’t switch planes.

Pro Tip: Always check the flight details to see how many legs are involved. If you’re sensitive to ear pressure or just want the fastest trip, you’ll want the fewest legs possible. One leg is always better than two, as it cuts the risk of operational hiccups in half.