Harriet Baskas

Special for USA TODAY

On Tuesday the Department of Transportation announced fines totaling $2.75 million against United Airlines for violations related to disability-related complaints in 2014 and long tarmac delays in 2013 and 2015.

“We will make sure that airlines comply with our rules and treat their passengers fairly,” U.S. Transportation Secretary Anthony Foxx said in a statement outlining the agency’s action.

DOT said that its review of “a significant increase” in the number of disability-related complaints against the carrier in 2014 “revealed that United failed to provide passengers with disabilities prompt and adequate assistance” getting on and off its airplanes and in moving through terminals at Houston George Bush Intercontinental Airport, Chicago O’Hare International Airport, Denver International Airport, Newark International Airport and Washington Dulles International Airport.

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The agency’s review also found numerous instances in which United delayed the return of passengers’ wheelchairs, other mobility aids or other assistive devices, or returned them damaged.

The $2 million fine breaks down this way:

DOT is requiring United to pay $700,000 within 30 days. The carrier must also spend $150,000 to improve quality assurance audits of contracted wheelchairs vendors and another $500,000 on a mobile app that helps passengers with disabilities request wheelchairs and other disability-related assistance at airports. The airline is being credited $650,000 for compensation it gave to consumers who filed a 2014 disability-related complaint.

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The DOT also outlined the findings behind a $750,000 fine to United for five lengthy tarmac delays that took place at Chicago O’Hare on Dec. 8, 2013, and one lengthy tarmac delay of a flight diverted to Houston Hobby Airport on May 20, 2015.

“…[T]he Enforcement Office found through its investigation that United’s gate mismanagement caused five flights to exceed the Department’s three hour limit on the tarmac for domestic flights,” DOT said in its statement. “In addition, due to a severe thunderstorm, a flight from Denver to Houston Bush Intercontinental diverted to Houston Hobby to refuel; however, the Department found no evidence that United attempted to deplane passengers before the tarmac delay reached the three-hour mark.”

DOT is requiring United to pay $375,000 of the $750,000 fine for these tarmac delay violations. United will also spend $375,000 on automated visual docking and guidance systems “that will allow aircraft to be parked in all-weather conditions and during irregular operations without marshallers.”

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Harriet Baskas is a Seattle-based airports and aviation writer and USA TODAY Travel's "At the Airport" columnist. She occasionally contributes to Ben Mutzabaugh's Today in the Sky blog. Follow her at twitter.com/hbaskas.