A government report says more than a fifth of air traffic controllers hired by the Federal Aviation Administration in recent years washed out before finishing their training.
The Department of Transportation's inspector general says in a report posted online Friday that the FAA has been underestimating the number of new hires who didn't finish their training.
Using a different methodology, the inspector general said 22 percent of new controllers who should have completed their training last year didn't. In 2009, 21 percent failed to complete their training, and in 2008 it was 31 percent.
FAA had previously estimated a 9 percent attrition rate for new controllers in 2009.
The agency is struggling to hire 11,000 controllers by 2019 to make up for a wave of retirements.