Add your TSA PreCheck number during booking or after you've purchased your ticket

You can add your TSA PreCheck number to an Aer Lingus flight in two ways: when you first book your ticket, or afterward through your booking management page. Aer Lingus calls this information your "Known Traveler Number" (KTN) in their system. The airline passes this number to TSA before your flight, which tells security screeners that you've already been vetted and may may have access to for expedited screening lanes.

The process takes less than five minutes either way. You'll need your TSA PreCheck membership number, which appears on your physical card or in your TSA PreCheck account online. If you're adding it after booking, you can do this up to 24 hours before departure, though earlier is better—some sources suggest adding it at least a week ahead to may support it syncs with TSA systems.

Key Takeaways

  • Your TSA PreCheck number is called a Known Traveler Number (KTN) on Aer Lingus's website and must be entered separately for each passenger traveling.
  • You can add your KTN when you first book your flight or edit your reservation afterward through the Aer Lingus website or mobile app.
  • Your TSA PreCheck number appears on your membership card or in your TSA account; you'll need the nine-digit number to enter it into Aer Lingus.
  • Adding your number does not may provide TSA PreCheck screening—TSA makes the final decision at the airport based on your membership status and the flight details.

Add your KTN when booking a new ticket

During the booking process on Aer Lingus's website or app, you'll reach a page asking for passenger details. After you enter your name, date of birth, and other required information, look for a field labeled "Known Traveler Number" or "KTN." This field is optional, but filling it in takes 30 seconds and ensures your PreCheck status travels with your reservation from the start.

Enter your nine-digit TSA PreCheck number exactly as it appears on your card. Do not add spaces, dashes, or letters. If you have multiple passengers on your booking, each person needs their own KTN entered separately—you cannot use one number for the whole group. After you complete your booking, Aer Lingus will store this information in your reservation.

Add your KTN to an existing Aer Lingus reservation

If you've already booked your flight without entering your TSA PreCheck number, you can add it through the Aer Lingus website. Go to "Manage My Booking," enter your booking reference (the six-character code in your confirmation email) and your last name, then click "Find Booking."

Once your reservation appears, look for an option to edit passenger details or add frequent flyer and traveler information. Select the passenger whose KTN you want to add, then enter your nine-digit TSA PreCheck number in the Known Traveler Number field. Save your changes. The update is when ready, though Aer Lingus recommends making changes at least 24 hours before your flight to may support the information reaches TSA's systems.

Where to find your TSA PreCheck number

Your TSA PreCheck number is printed on the front of your membership card in the bottom right corner. It is a nine-digit number that begins with numbers or letters depending on the program. If you don't have your card handy, you can find your number by logging into your TSA PreCheck account at universalenroll.dhs.gov. Click "Sign In," enter your credentials, and your membership details—including your KTN—will display on your account dashboard.

Your TSA PreCheck membership is valid for five years from the date you were approved. If your membership has expired, you'll need to renew it before TSA will honor your PreCheck status at the airport. Aer Lingus will accept an expired number, but TSA screeners will not recognize it, and you won't receive expedited screening.

What happens after you add your KTN to Aer Lingus

Once you've entered your Known Traveler Number into your Aer Lingus reservation, the airline transmits this information to TSA as part of your passenger data. TSA cross-references your KTN against its database of active PreCheck members. If your membership is current and valid, your boarding pass will print with a TSA PreCheck indicator—usually a checkmark or the words "TSA PreCheck" printed on it.

That indicator tells security screeners at the airport that you may be may be able to access for expedited screening. However, TSA makes the final decision at security based on your boarding pass, your ID, and current security conditions. Even with a valid KTN, you may occasionally be selected for standard screening instead. This is normal and does not mean your PreCheck membership is invalid.

Adding your KTN through the Aer Lingus mobile app

The Aer Lingus mobile app allows you to manage your booking and add your KTN on the go. Open the app, tap "Manage Booking," and enter your booking reference and last name. Once your reservation loads, select the passenger and look for the option to add traveler information or frequent flyer details. Enter your nine-digit TSA PreCheck number and save.

The mobile app syncs with Aer Lingus's website, so changes made in the app appear in your online account when ready. You can add or update your KTN through either platform—whichever is more convenient for you.

Frequently Asked Questions

What if I don't see a Known Traveler Number field on Aer Lingus?

The KTN field is optional and may not appear on every booking page or in every step of the process. If you don't see it during initial booking, you can always add it later through "Manage My Booking." Some older bookings or special fares may have limited editing options; contact Aer Lingus customer service if you cannot find the field.

Can I add my TSA PreCheck number after I've checked in?

No. You must add your KTN before you check in for your flight—ideally at least 24 hours before departure. Once you've checked in, your boarding pass is generated and locked. If you forget to add your number before checking in, you won't receive the TSA PreCheck indicator on your pass, and you'll go through standard security screening.

Do I need to add my KTN to every Aer Lingus flight I book?

Yes. Each booking is separate, and you must enter your Known Traveler Number for each reservation. Aer Lingus does not automatically carry your KTN from one booking to the next. If you book multiple flights, add your number to each one individually.

What if my TSA PreCheck membership expires before my flight?

You can still enter your expired number into Aer Lingus, but TSA will not recognize it at the airport. Renew your membership through the TSA website before your flight date if you want to use PreCheck. If your membership expires after your flight, you're fine—TSA checks the expiration date at the time of screening, not at booking.

Will adding my KTN to Aer Lingus may provide I get TSA PreCheck screening?

No. Adding your number ensures the information reaches TSA, and a valid membership should result in a TSA PreCheck indicator on your boarding pass. However, TSA makes the final screening decision at the airport. You may occasionally be selected for standard screening even with a valid PreCheck membership; this is part of TSA's random security procedures.