Why you never want to see these four letters printed on your boarding pass

Long queues, being packed cheek-by-jowl with other passengers, hand luggage rulings and restrictions that seem to change with the weather, generalised anxiety about the flight ahead, being barked at by overzealous staff: going through airport security is often a stressful and frustrating experience for the average traveller.

But if the prospect of being directed to remove your shoes to pass through the body scanner feels like an affliction, it’s worth taking a look at your boarding pass for a code that could make a significant difference to your airport experience.

Passengers flying into or within the US may have the misfortune to discover the letters SSSS on their flight documentation.

It stands for Secondary Security Screening Selection and means you can expect to be subjected to a much more intensive screening.

SSSS was introduced by the Transportation Security Administration (TSA), the branch of the United States Department of Homeland Security (DHS) that has authority over transportation security.

The TSA was established in response to the September 11 attacks in New York in 2001. Its website states that its “mission” is to “protect the nation’s transportation systems to ensure freedom of movement for people and commerce.”

Read more: Why are airport queues so long and what are passengers’ rights if they miss a flight?

People selected for SSSS can expect a much more extensive screening, with a full-body pat down, mandatory metal detector and body scanning, hand and foot swabs and a thorough unpacking and searching of both hand and checked luggage.

Passengers are often taken aside into a private room for the screening, which can add significant time to the pre-flight experience, with some travellers claiming that the delay has almost led them to miss their flight.

“I’ve gotten SSSS several times flying back from Europe,” wrote one user on Reddit.

“Once, the extra security screening (done before getting to the boarding gate in my case) was so slow that my flight left. United booked my partner and me on new flights for the next day and got us a hotel. We couldn’t get seats on the same flights, however, so she left earlier than me.

“Next day, we go back to the airport, I get my new boarding pass, and SSSS is on it again.”

While the TSA does not publish the criteria used to select people for SSSS, possible reasons may include:

Civil liberties groups have claimed that the SSSS ruling is both racist and infringes on privacy rights, however.

In 2023, the Council on American-Islamic Relations (CAIR), the country’s largest Muslim civil rights and advocacy organisation, filed a lawsuit with a dozen plaintiffs calling for an end to the SSSS process which they claim exclusively targets Muslims “for harassment and humiliation” when travelling.

In a statement, CAIR said: “The watchlist is Islamophobic. An expert statistical analysis of leaked portions of the 2019 watchlist estimates that at least 98.3 per cent of the names on the watchlist are identifiably Muslim.

“That doesn’t happen by accident.”

One traveller who was given the code explained what had happened to him to The Independent.

“I was flying to JFK and had only booked my flights a week earlier,” he said. “For some reason I couldn’t check in using the app as usual so I was worried something was wrong.”

After checking in at the desk he noticed the code. In the queue for the extra screening at Gatwick, he didn’t notice a particular trend amongst the people there but thought there might be more men and Asian people than there were on the plane as a whole.

His extra screening involved a swab being swept under the sole of his shoes and over his whole body which was then scanned.

He boarded the plane as normal afterwards.

Read more: What you can’t bring through airport security, according to a former TSA agent

Some passengers who regularly find SSSS appearing on their boarding pass have reported applying to the Department of Homeland Security for a redress number, which some claim reduces the likelihood of being singled out on future flights.

However, the likelihood of this being granted is slim, with the TSA explicitly stating on their website that the programme is “not designed to address travel issue (sic) related to discrimination, personal injury or assistance during screening for travellers with disabilities, medical conditions and other circumstances”.

“I had SSSS on both of my last return international flights,” wrote one flyer on Reddit.

“One from Frankfurt and the other from Liberia. On the flight home from Frankfurt (this was the second time in less than a month), I applied for a redress number from the Department of Homeland Security. The redress is supposed to prevent the SSSS from happening, though not a guarantee. The application said it would take several weeks, but I got my redress number in less than a week.”

Another added: “I've been pulled into the back twice coming back internationally. They explained that they immediately knew I wasn't who they were looking for as that person was 7“ shorter than me. Spent a bunch of time waiting back there because they said whoever it was is a high priority target and they had to get clearance from DC to release me.

“That's how I found out about redress. Have it now. Still get SSSS'd internationally periodically.”

Read more: Trans woman accuses TSA of targeting her at airport security