WASHINGTON--Nearly 30,000 airline passengers discovered in the past year that they were mistakenly placed on federal "terrorist" watch lists, a transportation security official said Tuesday.

Jim Kennedy, director of the Transportation Security Administration's redress office, revealed the errors at a quarterly meeting convened here by the U.S. Department of Homeland Security's Data Privacy and Integrity Advisory Committee.

Marcia Hofmann, staff counsel at the Electronic Privacy Information Center, said this appeared to be the first time such a large error has been admitted. "It was a novel figure to me," Hofmann said. "The figure shows that many more passengers than we've anticipated have encountered difficulty at airports. The watch list still has a long way to go before it does what it's supposed to do."

Kennedy said that travelers have had to ask the TSA to remove their names from watch lists by submitting a "Passenger Identity Verification Form" and three notarized identification documents. On average, he said, it takes officials 45 to 60 days to evaluate the request and make any necessary changes.

Travelers have been instructed to file the forms only after experiencing "repeated" travel delays, he said, because additional screening can occur for multiple reasons, including fitting a certain profile, flying on a one-way ticket, or being selected randomly by a computer.

Of the 30,000 people who said they were mistakenly placed on the list, none ever had been kept from boarding an airplane, Kennedy said. Their names appeared only on a "selectee list," where members are singled out for additional screening. Names on the "no-fly" list, however, are unilaterally barred from flying. The office said it hasn't been informed of any cases where people have disputed placement on the no-fly list.

After submitting their notarized forms and identifications, and waiting for evaluations, the vast majority of the people mistakenly placed on the watch list have now been added to a "clearance" list. That doesn't mean their names are erased from the watch list. In fact, travelers who go through the paperwork are told, Kennedy said, that "it will not quote 'remove' you from the list because the person we're still looking for is out there."