Aircraft Warning Ineffective in Clouds

A new system of lasers designed to warn pilots that they have entered restricted airspace over Washington can’t be used on planes flying in or above the clouds, officials said Tuesday.

The problem is, clouds cover most of the sky almost half the time in the nation’s capital.

The limitations of the laser warning system were evident during an airspace violation Monday, when military F-16s escorted a small plane from a restricted area to a nearby airport.

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.

The plane had permission Monday to fly through the restricted airspace en route to Gaithersburg, Md., from Knoxville, Tenn., because the pilot filed a flight plan and maintained radio contact with air traffic control, Federal Aviation Administration spokesman Greg Martin said.

But lightning struck the small Canadian aircraft, knocking out its radio, Martin said Tuesday.

Government officials who spoke on condition of anonymity said that the pilot’s mistake was he didn’t switch his transponder code to indicate he had no radio.

On May 11, a Black Hawk helicopter, a Citation jet and two F-16s were scrambled to intercept a plane that flew unusually deep into the restricted zone, about three miles from the White House.

Thousands of people were evacuated from government buildings.

The FAA revoked the license of that pilot, Hayden L. Sheaffer, on Monday after determining he was so careless that he “constitutes an unacceptable risk to safety in air commerce.”

The Washington Post reported today that Defense Secretary Donald H. Rumsfeld gave military officials the authority to shoot down Sheaffer’s plane if necessary. A federal official told the Post that the plane came within “15 to 20 seconds” of being downed.

The new details, corroborated by a senior federal law enforcement official briefed on the events, came as U.S. military and Homeland Security officials reviewed the effectiveness of the air defense system.

As authorities piece together the lessons of the scare, described by some officials as the closest the government has come to downing a civilian plane over Washington since the Sept. 11 terrorist attacks, they are confronting issues involving split-second decisions, communications and the federal chain of command.

Against a light aircraft moving at a relatively slow 100 mph, authorities were able to order the evacuation of the White House and Capitol only minutes before the plane would have reached those targets.