It turns out it was the pilot who caused a United Airlines flight from Chicago to Frankfurt, Germany, to make an emergency landing in Toronto. Or, rather, it was his coffee.

Flight 940 with 241 passengers aboard landed safely at Pearson International Airport around 10 p.m. ET on Monday after experiencing problems with the plane's communications equipment.

The U.S. Federal Aviation Administration has informed Transport Canada the airline has indicated the problem occurred after the pilot in command spilled coffee on the radio equipment.

Rather than continuing the flight over the Atlantic, the captain and the crew decided to take the plane to Toronto, where it could be fixed, United spokesperson Rahsaan Johnson said Monday.

Another plane was sent to pick up the passengers and take them back to Chicago, where they were able to board another flight for Frankfurt on Tuesday morning.

The incident is being investigated.