Flaws in how the Transportation Security Administration tracks what it confiscates from people seeking to board commercial airline flights in the U.S. renders the data all but worthless, the Salt Lake Tribune reports.

Those flaws may mean TSA lacks an accurate understanding of the nature of the threats it must deal with at the nearly 450 airports the agency is responsible for screening.

"For example, TSA stopped counting confiscated firearms for three years. In 2008, it quit counting eight of 13 major categories of banned items, including knives, ammunition and box cutters (the weapon used by 9/11 terrorists)," the Utah daily said today on its front page.

"The hit-and-miss data show TSA does not know how many total prohibited items are surrendered, so it cannot accurately track rates of such activity nationwide or at specific airports," the paper said.

The paper quoted Douglas Laird, head of an aviation security consulting firm, who said "if TSA is continually changing the parameters of how they test, truly they have no idea of how they are doing," said Douglas Laird, head of an aviation-security consulting firm. He is the former security director of Northwest Airlines and a former Secret Service agent.

A TSA spokesman told the Tribune that the changes in data collection do not constitute a significant problem.

Even so, the Tribune said TSA confiscated the highest number of potential weapons passengers attempted to take aboard a commercial airline flight in 2005 when the total was 15.7 million, or one for every 46 passengers that year.

"But in 2010, the last year for which TSA data were released, records show TSA collected a mere 109,270 banned items -- a 99 percent decrease from five years earlier and a record low. That amounts to one item for about every 6,700 passengers," the Tribune said. "The vast difference comes not from a dramatic increase in travelers leaving banned items at home but mostly from changes in what TSA counted."

Go here for the rest of the Tribune story.