Air travel can be stressful. Between organizing your luggage, catching your flight on time, and navigating crowded airports, things can quickly go wrong. If your day is already hectic, the last thing you want is extra attention from airport security.

If you spot the code “SSSS” on your boarding pass, get ready to meet TSA staff more closely. According to Business Insider, those four letters indicate Secondary Security Screening Selection. In other words, you’ve been pre-selected for additional security screening.

The “SSSS” is part of the Secure Flight program, a risk-based pre-screening system. A TSA spokesperson explained:
“Secure Flight identifies low- and high-risk passengers before they arrive at the airport. It matches names against trusted traveler lists and watchlists to enhance security.”

The program collects basic information—like your name and date of birth—to make these matches. It also helps prevent people on the No Fly List or the CDC Do Not Board List from flying. Read more below