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A United Airlines flight from Newark, N.J., to Palma de Mallorca, Spain, pulled a U-turn late Saturday over what appears to have been a suspiciously named Bluetooth device on board.

Flight tracking data shows that the flight, which should have landed in Spain after a nearly eight-hour flight, instead returned to Newark after 4 hours and 24 minutes in the air.

United Airlines told NPR via email that the flight turned around "to address a potential security concern." Multiple posts on social media from self-identified passengers indicate that the problem was a Bluetooth device on board the plane. Several of those passengers posted photos or videos of them on board the flight or in the airport, with timestamps that match the flight's actual schedule.

Some passengers knew little more than that the flight attendants had asked passengers to turn off their Bluetooth devices. One post referenced in-flight announcements with "lots of comments like 'this little joke is ruining it for everyone.' "

Audio from air traffic control, archived by LiveATC.net, sheds a little more light on the situation. One voice on the recording asked what had happened with the flight, which had recently landed back at Newark and remained on the tarmac.

"There's a security detail out there, someone had a Bluetooth speaker and they named it a certain four-letter word," another voice responded. "So they have to inspect the whole aircraft including the cargo area [and] passengers have to evacuate."

"That's crazy," the first voice replied.

"Four-letter word," in this case, doesn't appear to refer to a curse word, but rather a different four-letter word that triggered airline security procedures.

"There is an active Bluetooth network labeled 'BOMB,' " one self-identified passenger wrote on TikTok. (She shared a video of herself drinking sangria, geotagged to Palma de Mallorca, after the flight finally arrived.) Another Reddit post of someone who claimed to be the spouse of a passenger similarly reported that the word in question was "bomb" and that the device was a teenager's speaker.

The flight eventually reboarded and landed in Palma de Mallorca at 3:47 p.m. local time on Sunday, about 9 and a half hours late.