Some people have, and it has often led to some frustrating and lengthy airport delays.

So for those who are lucky enough to not know what it is and have never experienced it, what does this four letter code mean?

In short, the code SSSS is used on domestic and international US flights to indicate that additional security screening should be carried out.

Airport security in many countries was beefed up significantly after the events of 2001.

The US Transport Security Administration (or TSA) was formed at this time, and has increased security since with several schemes, including the Secure Flight program.

The use of ‘SSSS’ codes has been formalized and strengthened under this, but its use is reported before then as well. 

According to TSA: "Secure Flight is a risk-based passenger prescreening program that enhances security

by identifying low and high-risk passengers before they arrive at the airport by matching their names against trusted traveler lists and watchlists."

Passengers are screened for security using government databases and their travel information.

This can result in several actions—of course, travel could be denied and law enforcement involved in the most severe cases,

while passengers identified as being of increased risk and requiring extra checks will have the code ‘SSSS’ printed prominently on their boarding pass.

Security and border agents then know to apply enhanced security checks.

This is used by TSA on all US domestic flights and international flights from the US.

Several factors influence the use of ‘SSSS,’ but the exact processes and decisions are not made public for obvious security reasons.

Being on security watchlists—including the FBI counter-terrorism watchlist—is sure to trigger the code. 

Other factors might include the booking of one-way trips, booking flights last minute, or frequent recent travel.

Travel between certain airports, or to or from certain countries, will make it more likely as well.

Discrepancies between boarding pass and passport or ID information could also be to blame.

Additionally, ‘SSSS’ is sometimes assigned at random. 

Extra security checks are, of course, good in the overall scheme of improving security, but for individual passengers, they can be frustrating.

Having the code on your boarding pass will likely subject you to more checks and a longer time to clear security.

These are not usually carried out separately, but will delay you as part of the main security screening. 

Extra screening might mean additional scans, a more thorough check of luggage, and taking swabs from your hands, clothes, or baggage to check for narcotics or explosives.

Agents are also likely to ask you questions about your travel, and you may have to wait while additional passport or identity checks are carried out. 

One of the problems with ‘SSSS’ is the same travelers tend to get selected repeatedly.

Fortunately, there are some ways to address this—although nothing is guaranteed, and you may still be highlighted for security reasons.

Joining the TSA PreCheck program is reported to help. 

There is also a US Homeland Security process for addressing security problems, including ‘SSSS’ codes and issues with watchlists.

The DHS Traveler Redress Inquiry Program allows travelers to report issues with boarding and airport security—issues that will be investigated and evaluated. 

Have you ever seen ‘SSSS’ on your boarding pass? What extra checks did you experience? Let us know by leaving a comment.

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