Secondary Security Screening Selection or Secondary Security Screening Selectee, known by its acronym SSSS, is an airport security measure in the United States which selects passengers for additional inspection. This may also be known as Selectee, Automatic Selectee or the Selectee list.
Some criteria are:
Since neither the TSA nor the airline run a background check at the time boarding passes are issued, immigration status and criminal records are not taken into consideration during SSSS. Furthermore, personal information such as a passenger's addresses, employment history, and medical records are not taken into account during SSSS and may not even be readily available to government officials to modify the process and increase its validity.
SSSS passengers will go through a more intensive screening process which may include puffer explosive detectors. Their carry-on luggage may be also be inspected by hand. In the case of film or other items that cannot be X-rayed, the agent may perform a test for possible explosive materials. The screener may also use a hand held metal detector to search the passenger for metal objects.
The efficiency of SSSS is highly questionable, since at least with British Airways and Alaska Airlines the marking happens as mentioned at check-in. Thus a potential miscreant is warned and has the opportunity to leave the public area of the airport or abandon an attempt to smuggle something on board, while other passengers will be continue to be screened.