Airline passengers are used to dealing with delays caused by weather, technical issues, or overcrowded airports. A Bluetooth device name probably isn’t on that list, yet that’s exactly what appears to have forced a United Airlines flight to abandon its trip and head back to where it started.

NPR reports that a United Airlines flight headed from Newark, New Jersey, to Palma de Mallorca, Spain, was forced to turn back midway through its journey after crew members detected a Bluetooth device broadcasting the name “BOMB.” What may have started as a poorly thought-out joke quickly turned into a serious security concern, prompting the aircraft to abandon its transatlantic route and return to Newark.

The aircraft had already been in the air for more than four hours and was roughly midway when the decision was made to return to Newark. United Airlines has only said that the flight was diverted due to a “potential security concern,” but passenger reports and air traffic control recordings have since shed more light on what happened.

According to those accounts, authorities were alerted after an active Bluetooth device with a suspicious name was detected onboard. That alone was enough to trigger standard security protocols. In an era where airlines take every possible threat seriously, there is little room for assumptions, even when the source turns out to be something as ordinary as a wireless gadget.

Passengers were asked to switch off Bluetooth on their devices while crew members and authorities attempted to identify the source of the signal. Once the plane landed back in Newark, everyone on board was evacuated so security teams could thoroughly inspect the aircraft and its cargo.

Several passengers later claimed on Reddit that the Bluetooth device was a portable speaker belonging to a teenager who had renamed it “BOMB.” Those reports remain unconfirmed by officials, but if accurate, it would be a costly reminder that a joke made on the ground can have very different consequences at 35,000 feet.

It’s easy to see why airlines respond aggressively in situations like this. A suspicious device name may sound harmless in hindsight, but crews don’t get the luxury of waiting to find out. The risk of ignoring a potential threat is simply too high.

After security personnel cleared the aircraft, the flight eventually resumed its journey to Spain. By then, however, passengers had lost nearly ten hours — not bad for a Bluetooth name that probably took all of five seconds to type.