A 48-year-old male passenger, whose name was not released, used a $22 device called the Knee Defender—banned by some airlines, including United—to prevent the woman in front of him from reclining her seat.
The man ignored a flight attendant’s request to remove the device, at which point the woman in front of him, also 48, stood up and threw a cup of water at him.
The conflict escalated, and the plane was forced to divert to Chicago’s O’Hare airport. The feuding passengers were removed and the flight continued to Denver, arriving around one hour and 38 minutes late.
The passengers had been seated in United’s Economy Plus section, which offers four inches of extra legroom.
The device the man used, the Knee Defender, is a plastic gadget that clips onto the hinge of an airline seat’s folding tray, preventing the person in front of you from reclining.
Though the FAA hasn’t prohibited the device, several airlines, including United, American Airlines, and Northwest, have banned the contraption.
The passengers on the United flight may have taken their disagreement to the extreme, but the incident raises one of the most hotly contested questions of air travel: should you recline your seat?