Travelers who have enrolled in expedited security programs like TSA PreCheck may miss their flights if they fail to add their Known Traveler Number (KTN) to their reservation. The KTN, also referred to as a PASSID depending on the enrollment program, is a 9-to-10-digit number essential for accessing TSA PreCheck or other expedited screening services such as Global Entry, NEXUS, or SENTRI.

According to the Transportation Security Administration (TSA), a KTN is a unique identifier assigned to individuals approved for these programs. Without the KTN correctly listed on a boarding pass, passengers cannot use the PreCheck lanes. "If your boarding pass doesn’t have the clearance, you won’t be permitted through the PreCheck line," Madison Kinsler, a flight attendant at Southwest Airlines, told HuffPost. Instead, they must join the general screening line, which can be considerably longer.

Valerie Fraser, a flight attendant and photographer, described seeing general TSA lines extend for one to three hours during peak travel times with limited staffing. In contrast, TSA data indicates that approximately 99% of passengers using TSA PreCheck lanes wait less than 10 minutes.

If a traveler reaches the TSA agent without a KTN on their boarding pass, they may be denied entry to the expedited lane and instructed to wait in the general line or to add the number and return. Kinsler advised, "Adding all your important and accurate information to your reservation ahead of time will alleviate you potentially having to wait in long customer service lines at the airport."

There are multiple ways to add a KTN to a reservation:

  • Airline App or Website: During online check-in, travelers are typically prompted to enter their KTN. It's advisable to verify this information even if it was entered during the initial booking.
  • Self-Service Kiosk: At the airport, the KTN can often be added at self-service kiosks when printing bag tags and boarding passes.
  • Customer Service Desk: As a last resort, travelers can consult with a customer service representative at the airport, who can add the KTN to the reservation and issue updated boarding passes.

Kinsler noted that if it is too close to the flight's departure, a traveler might not be able to add the number themselves and will need assistance from an agent.

Travelers who have forgotten their KTN can retrieve it through the specific program they used for enrollment. The TSA website provides a list of resources for locating a lost KTN.

It is recommended that passengers add their KTN to their ticket before arriving at the airport to ensure everything is in order. If traveling with multiple individuals, ensure each person's KTN is also added to their respective reservations to avoid separation at security.