JetBlue, the New York-based carrier, is the first U.S. airline to begin installing a cabin surveillance camera system on its aircraft.

Linked to the airline's onboard DIRECTV system, four cameras provide a constant stream of video to two cockpit monitors, enabling the captain and co-pilot to keep an eye on passengers throughout the flight and take action if they notice a disturbance.

JetBlue just installed the cameras on one of its Airbus A320s and plans to place the systems on the rest of its 23 planes, said spokeswoman Fiona Morrisson. In October, the airline outfitted its fleet with Kevlar bulletproof cockpit doors with titanium bolts that can only be opened from the inside.

"This just gives an extra element of security for everybody," Morrisson said.

The goal is to thwart a hijacking attempt or other safety threat: "It's not to stop Mr. Jones in 14C — 'Would you please put your feet down,' " she said.

Inside JetBlue's cabin, some of the tiny cameras, measuring about one inch square, are visible, while others are hidden, said Glenn Latta, executive vice president of LiveTV, which provides the surveillance system.

LiveTV, based in Melbourne, Fla., recently became the first company to receive Federal Aviation Administration certification for the systems. The company also provides 24-channel satellite TV on all of JetBlue's planes. JetBlue operates 118 daily flights, including several out of Salt Lake City International Airport.

Latta said LiveTV is in discussion with several other domestic and international carriers about installing the systems.