Flight cabin crews call the shots in fights over reclining seats

Smart Tray International makes three versions of a tablet-friendly airplane tray table that support travelers' devices or those provided by an airline.
Source: Smart Tray International
Smart Tray International makes three versions of a tablet-friendly airplane tray table that support travelers' devices or those provided by an airline.

A recent surge in flights getting diverted because of passengers fighting for recline space can be chalked up to flight attendants feeling they've run out of options when dealing with unruly passengers.

A Delta flight from New York to West Palm Beach, Florida, was diverted to Jacksonville, Florida, on Sunday after a woman resting her head on a tray table was upset when the passenger in front of her reclined his seat, hitting her head.

It was the third such diversion in eight days after passengers got into disagreements over seat reclining. On Aug. 24, a United Airlines passenger stopped the woman in front of him from reclining by using a plastic device called the "Knee Defender."The $21.95 gadget attaches to the tray table arms and prevents the seat in front from leaning back. A flight attendant told him to remove the device, which, though allowed by the FAA, is banned by U.S. airlines. He refused. The passenger ahead of him then allegedly dumped a cup of water on him.

Read MoreFight on board airliner boosts 'Knee Defender'

Three days later, an American flight from Miami to Paris was diverted to Boston, also because of a passenger fight over reclining seats.

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It's not that the skies are getting any less friendly, however.

"It's the echo effect," said Joe Brancatelli, former executive editor of Frequent Flyer magazine. After the "Knee Defender" incident lit up social media and news coverage, "the two subsequent incidents are basically flight attendants saying, 'Why would we deal with this when another crew decided to divert?'"

Pilots have sole discretion to divert flights if they believe there is a threat to other passengers or to the plane. Federal law prohibits passengers from interfering with the performance of a crew member's duties, which could present a safety hazard. Interpreting what constitutes interference is up to the crew.

"It could be that the crew is giving them instructions and they're not heeding those instructions. They could be out of their seat," said FAA spokesperson Alison Duquette.

Flight attendants say they're often left with little choice when dealing with unruly passengers.

"We can't call the cops or an ambulance or the fire department in flight," said flight attendant Heather Poole. At 35,000 feet, she said, "there's no telling how things are going to escalate."

Stoking the issue are the increasingly close quarters passengers have had to endure.

Flights themselves are fuller. Planes flying at 85 to 95 percent capacity are common. Seat pitch, the distance between seats, began shrinking during the airline bankruptcies of the early 2000s from a standard 32-34 inches to 31 or 30. Seats must pass a federal formula designed to limit head injuries, but there are no minimum passenger seat space requirements.

At the same time, airlines have stuffed in more seats and rows. Earlier this summer, airplane manufacturer Airbus filed a patent for a design as minimal as a bicycle seat.

Read MoreUnited Jet diverted as fliers fight over Knee Defender device

"As airlines are cramming more people into a confined space, the likelihood of conflict increases," said Sara Nelson, a spokesperson for the Association of Flight Attendants union. The union has not specifically directed its members to divert flights during these incidents, but recommends they they follow their airline's policy manuals.

Meanwhile, she said, flight attendants are stressed by staff cutbacks, increased responsibilities, longer hours and pay that's slow to rise. "At some point there's a breaking point."

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--By NBC News's Ben Popken