The Air Force's inability to keep track of its huge equipment and supply inventory has resulted in excessive purchases costing "billions of tax dollars," a senator says.

Sen. John Glenn, D-Ohio, on Wednesday released a report by the General Accounting Office concluding that the accuracy of Air Force inventory records continues to be a problem despite improvements in inventory control.The report also said the Air Force continues to have difficulty determining the causes of inventory inaccuracies and that physical security of the supplies needs to be improved.

Glenn, chairman of the Senate Governmental Affairs Committee, said Air Force supply items and repair parts are worth more than $21 billion.

"While many of these parts are essential to keeping our planes in the air, poor inventory control has resulted in excessive supply purchases costing billions of tax dollars," said Glenn. "The Air Force needs to straighten up and fly right when it comes to inventory management."

The GAO study was based on audits of the Air Force Logistics Command headquartered at Wright-Patterson Air Force Base near Dayton, Ohio, and air logistics centers in San Antonio, Texas; Sacramento, Calif.; and Ogden, Utah.

The GAO, the investigative arm of Congress, said the Air Force's adjustment policy allows inventory rec-ords and on-hand supplies to remain out of balance by as much as 10 percent and $4,999.

"Air Force item managers continue to adjust inventory records without performing adequate research to identify the primary cause for discrepancies," the GAO said. "The risk in this policy is that the records may be erroneously adjusted, possibly resulting in apparent shortages of needed items which are actually on hand, or excess procurements."

The GAO also said the physical security at the Air Force centers in San Antonio, Sacramento and Ogden needs to be improved to lessen the risk of theft.

It said the storage buildings at Sacramento and Ogden are not separately surrounded by security fencing and that privately owned and contractor vehicles are permitted to park right next to warehouses at all three centers.

Jack Katzen, a deputy assistant secretary of defense at the Pentagon, said there have been steady and significant improvements in inventory accuracy at the Air Force, with accuracy rates approaching 95 percent.

"While these improvements are commendable, the department recognizes that problems still exist that require continued dedication and vigilance," Katzen said in a March 17 letter to the GAO. "The department is pursuing its aggressive action plan to continue improving the process."