Transcript for Fight for Space on an Airplane in Mid-Air
Now to the passenger plane forced to land because of a mid-air fight in the cabin. Two passengers battling in their seats over leg room and that tiny precious amount of space for the hours ahead. ABC's David Kerley shows us what caused the trouble. Reporter: It all began on a flight from Newark to Denver in economy plus, where you pay for some extra room. The woman in 11-b couldn't recline because a man behind her in 12-b put a $22 piece of plastic on the seatback to keep her seat from reclining. A source tells ABC news the man refused to move the gadget, so the woman stood up and threw a cup of water in his face. A faceoff that prompted a landing in Chicago. Both passengers were removed from the aircraft but not charged. The man was using these, they're called the knee defenders. On this flight, we enlisted Rick to help us show the frustration when somebody brings their seat back very quickly. That's where these knee defenders come in. You slide them on the tray and when Rick tries to bring his seat back again, it won't come back. The problem is the airlines don't allow the use of the knee defenders. Knee defenders aren't about getting more space. . Reporter: He should know, he invented the gadget. The idea is to let the person know that you're back there. Reporter: This as the flight is more crowded and there's less room. Carriers are squeezing your leg room. A couple of decades ago, 34 inches in coach. Down now to 32 or 30 inches. Some low fair operators have even cut that to 28 inches, all to squeeze in another row. This is all about profit. The problem is, we as passengers suffer. Reporter: Already squeezed. But look at this concept seat. You would be nearly standing up on your flight of the future. David Kerley, ABC news, new York.
This transcript has been automatically generated and may not be 100% accurate.