The U.S. Department of Transportation last month assessed a civil penalty of $125,000 against Minneapolis-based Mesaba Aviation for violating rules protecting air travelers with disabilities.

Complaints filed in 2007 and 2008 revealed a number of violations of the federal requirement to provide adequate enplaning and deplaning assistance, according to the DOT. The department also cited instances in which the carrier did not respond in writing to complaints from passengers with disabilities or notify them that they could refer their complaints to the DOT.