FAA warns pilots in Las Vegas vicinity on GPS

Pilots flying at night near Las Vegas over the next week may have to navigate the old-fashioned way - without GPS.

The Federal Aviation Administration is warning that navigation systems based on GPS technology may be "unreliable or unavailable" in about a 350 mile-radius that includes Las Vegas. LightSquared - a Reston, Va., company that plans to deploy an ultra-fast nationwide wireless broadband network of 40,000 transmitters and cell towers - is field testing its equipment in Nevada southeast of Las Vegas.

The tests are part of a deal LightSquared worked out with the Federal Communications Commission. The company has rights to frequencies located very close in the electromagnetic spectrum to those used for GPS. But the company's signals will be stronger than GPS signals, raising concern that they'll jam GPS in the vicinity of LightSquared transmitters.

Pilots said they see some irony in FAA's warning given the effort expended by regulators and the airline industry to keep passengers from jamming cockpit equipment.

"Flight attendants tell you to turn off your cellphones and your Kindles and whatever else because it may interfere the plane's electronics ... and yet I got this notice from FAA that somebody is going to do exactly the same thing, which is interfere with the navigation of the airplane," said John Gadzinski, an airline captain and aviation safety consultant.

All airliners and many other kinds of planes have backup systems that don't involve GPS. Also, many planes continue to use radio signals from FAA ground stations to navigate rather than GPS. That's been the primary means of aircraft navigation for the last half century. GPS is eventually expected to almost entirely replace radio signals.

Gadzinski also questioned the choice of the Las Vegas for testing.

"It's a hugely popular airport with a lot of traffic and a lot of terrain and a lot of reliance on GPS," he said.

Jeffrey Carlyle, LightSquared's executive vice president, said the Las Vegas area was chosen because it has several types of terrain that the company was looking for, including flat land with little or no "ground clutter," suburban areas with low-rise buildings and urban areas with taller buildings.

"You want to get a sense of how the signal acts in those different environments," Carlyle said. Las Vegas has little air traffic between 11 p.m. and 5 a.m. when the testing will take place, he said.

Dick Knapinski, a spokesman for the Experimental Aircraft Association, which represents 175,000 recreational pilots, said most pilots will see the FAA notice and plan to use something other than GPS to navigate.

"It's like if you are in your car or truck and you've been relying on GPS to get someplace, but you might want to make sure you still have a map in your car and get it out," Knapinski said.

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