• A United Airlines flight turned back to Newark, New Jersey, after 90 minutes.
• It's the latest example of a flight to nowhere — when flights return to their origin.
• Passengers eventually made it to London 12 hours later than scheduled.

United Airlines passengers faced a 12-hour delay after their transatlantic trip became a flight to nowhere.

Saturday's flight from Newark, New Jersey, to London was in the air for about 90 minutes when it U-turned just off the coast of Nova Scotia, according to data from FlightAware.

The flight-tracking website shows that after landing back in New Jersey at about 2:30 a.m. ET, the Boeing 767 didn't take off again for nearly five more hours.

Flight UA940 ultimately made it to London Heathrow at 7.29 p.m. local time on Sunday — 12 hours and 5 minutes after it was initially scheduled.

In a statement shared with Business Insider, a United Airlines spokesperson said the flight returned to Newark "to address a disruptive passenger."

The statement added that law enforcement removed the passenger before the flight continued to London that morning.

One Reddit user who said they were on the flight said the plane turned around after a business-class passenger threatened the aircraft's security.

They added that the delay at Newark was compounded by the flight crew reaching their maximum time on the clock, so new staff had to be brought in from standby.

The Port Authority of New York and New Jersey didn't immediately respond to a request for comment sent by BI outside US working hours.

Returning all the way to Newark rather than landing at a nearer airport in Canada may initially seem a strange decision, but so-called flights to nowhere aren't uncommon. Going back to an airline's hub airport usually means it's simpler to reroute passengers and solve any issues.

There have been several flights to nowhere in recent weeks.

Last month, a Delta Air Lines plane turned back over the coast of Newfoundland after the crew observed a potential engine issue.

Then, a KLM flight U-turned over the Atlantic Ocean and headed back to Amsterdam in a four-hour flight to nowhere as a precaution because of a technical malfunction.

• A Delta Air Lines flight unexpectedly stopped in Dublin on Wednesday.
• A man in his 30s was arrested after an incident on board, the Irish police told Business Insider.
• The Delta flight eventually continued to Atlanta, where it landed nearly three hours late.

Delta Air Lines passengers had an unexpected layover on Wednesday when their transatlantic flight diverted to Dublin.

Flight DL83 was 90 minutes into its journey from Paris to Atlanta when it changed course toward Ireland, data from Flightradar24 shows.

The Airbus A330, which had departed nearly 20 minutes late, then spent nearly two hours in the Irish capital.

Images shared on social media appeared to show a man being led off the plane in handcuffs.

Ireland's police force, An Garda Síochána, told Business Insider it charged a man in his 30s after being arrested following an incident on an aircraft. The man was due to appear in court that afternoon.

In a statement shared with BI, Delta said the plane had to stop in Dublin to remove an "unruly customer."

Aviation A2Z reported the fire service was standing by at Dublin Airport because the plane had to make an overweight landing. It couldn't dump fuel, given it was set to continue flying across the Atlantic.

Dublin Airport did not immediately respond to a request for comment sent by BI.

The plane left Dublin before landing in Atlanta at 3:31 p.m. ET — almost three hours later than scheduled.

"Delta has zero tolerance for unruly behavior and will work with law enforcement authorities to that end," the airline said in its statement. "We apologize to our customers for the delay in their travel."

This wasn't the first time a transatlantic flight has had to divert to Ireland.

In May, a United Airlines flight from Zurich to Chicago turned around after a passenger's laptop got stuck in their seat — posing a potential fire risk due to its lithium battery.

And back in 2019, a Condor flight from Germany to Mexico diverted to Ireland after a pilot spilled coffee on the plane's controls.