WASHINGTON -- Lasers designed to warn pilots they have entered restricted airspace over Washington can't be used on planes flying in or above the clouds.
Trouble is, clouds cover most of the sky here almost half the time.
The limitations of the laser warning system were evident during an airspace violation Monday, when F-16s escorted a small plane from out of a restricted area.
The laser system wasn't engaged because it couldn't penetrate the clouds over which the pilot was flying, said 1st Lt. Lisa Citino, a spokeswoman for the North American Aerospace Defense Command.
Between sunrise and sunset, clouds covered at least 88 percent of the sky over Reagan Washington National Airport for 162 days last year, according to the National Climactic Data Center.
Most small planes fly below the clouds, said Chris Dancy of the Aircraft Owners and Pilots Association. "The laser would still be effective," Dancy said.
Storm knocked out radio
During Monday's incident, the plane had permission to fly through the restricted airspace because the pilot filed a flight plan and maintained radio contact, said Federal Aviation Administration spokesman Greg Martin.
But lightning struck the small Canadian aircraft and he lost his radio, Martin said Tuesday. Officials who spoke on condition of anonymity said the pilot failed to switch his transponder code to indicate he had no radio.
Citino said fighters are scrambled when planes enter the zone and don't communicate with the ground.
On May 11, fighters were scrambled to intercept a plane that flew unusually far into the zone. Thousands were evacuated from government buildings.
That pilot, Hayden L. Sheaffer, had his license revoked on Monday.
Sheaffer said Tuesday he thought he was going to get "shot out of the sky" on May 11. "There was no doubt in my mind," he said.
Appearing on NBC's "Today" show with his lawyer, Sheaffer said he turned to a frequency that authorities had asked him to call but that he could not get through.
The New York Times reported that the Homeland Security Department acknowledged that Sheaffer was instructed to use a frequency that was not available.