The TSA has a list of people it secretly follows around the country –

The TSA has a list of people it secretly follows around the country

The Transportation Security Administration (TSA) has been using undercover federal air marshals to monitor suspicious passengers, according to a report published by the Boston Globe this week.

The ominously named “Quiet Skies” program aims to gather information about potential threats who are not on any terrorist watch lists or under investigation by any other agency.

When someone on the Quiet Skies list is selected for surveillance, a team of air marshals will board their next flight and monitor them.

“These programs are not designed to observe the average American,” Michael Bilello, an assistant administrator of public affairs for TSA, told The Hill. “They’re designed to protect the traveling public, but they’re not targeting the average American. We’re talking about a very unique passenger that warrants the attention of a federal air marshal.”

Once they are being monitored, a sudden loss of weight, a new tattoo, barely sleeping on the flight or sleeping for the entire flight are all behaviors that could be noted by air marshals.

According to Bilello, a person is dropped from the Quiet Skies program within 90 days or three monitored flights (whichever comes first) if they do not arouse any additional suspicion.

Documents from the agency show that there are between 40 and 50 “Quiet Sky” list passengers on domestic flights every day. About 35 of them are monitored by air marshals. Frequent foreign travel, especially to “countries that we know have a high incidence of adversarial actions,” is the first warning sign that could garner inclusion on the list, according to NPR.

Deploying air marshals to gather intelligence on passengers is a relatively new move, according to the Boston Globe. The practice started in 2010, with revamps in 2012 and March of this year.

The report also quoted air marshals who questioned the practice’s efficacy and legality.