A regional carrier that provides service for both Delta Air Lines and United Airlines is facing a $200,000 federal fine for its treatment of travelers with disabilities.

The action from the U.S. Department of Transportation comes after a review of passenger complaints found a number of violations involving Atlantic Southeast Airlines between January 2009 and May 2010.

Federal investigators say the airline failed to properly assist passengers using wheelchairs when boarding and deplaning aircraft.

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The airline, which flies under the names Delta Connection and United Express, may use up to $75,000 of the civil penalty to improve services for customers with disabilities.

The fine against Atlantic Southeast comes just months after the Transportation Department cited Delta Air Lines for similar violations. In February, Delta was fined $2 million in what was the largest ever federal penalty against an airline that was not safety related.

“Passengers with disabilities have rights and they have a right to be treated fairly and with respect by the airlines,” said Transportation Secretary Ray LaHood. “We will continue to take enforcement action when our disability rules are violated.”