U.S. investigates O'Hare controller errors

CHICAGO, March 2 (UPI) -- Federal investigators visited Chicago's O'Hare International Airport Wednesday to probe rising air controller errors, the Transportation Department says.

Federal Aviation Administration figures show a recent increase in mistakes while veteran controllers train new ones, the Chicago Tribune reports.

Training has been accelerated to cope with flight increases expected after O'Hare gets new runways.

FAA data show 17 errors in the most recent one-year period, up from six the previous year.

Most of the incidents involve failing to keep proper distance between airplanes, both horizontally and vertically. Two of them were classified as serious.

The worst error, which did not occur during training, happened when the wake from one plane gave another turbulence, breaking a rule to keep aircraft 1,000 feet apart vertically in such a situation. No one was injured.

Many longtime air traffic controllers spend all their time in the tower training new colleagues, FAA and union officials said. They are still fully responsible for problems even if they are not working the airplanes themselves.

Controllers told the Tribune being held accountable for trainees' actions adds to their considerable job stress.