American Airlines has been fined $1.6 million for forcing passengers to wait too long on the tarmac.
But American Airlines will only pay $695,000.
Most of the airline's tarmac delays are the result of 20 of its planes being grounded during a 2013 blizzard that hit Charlotte, North Carolina.
Federal rules don't allow domestic flights to stay on the tarmac for more than three hours without at least giving passengers a chance to leave the plane.
The Department of Transportation called the fine "the highest amount assessed against an airline for violating the tarmac delay rule."
The DOT, however, also said that $602,000 of the fine "will be credited to American for compensation provided to passengers on the affected flights."
It said another $303,000 "will be credited to American" for acquiring and maintaining a new surveillance system at the Charlotte and Dallas-Fort Worth airports.
"The remaining amount ($695,000) will be paid to DOT," Matt Miller, a spokesman for American, said in an email.
The DOT did not immediately respond to a CNNMoney request for comment.
American Airlines broke the DOT's tarmac delay rule 27 times in 2013 and 2015, according to a federal investigation.
The department did not cite any violations for 2014.
American Airlines told CNNMoney that "a large portion of the settlement" was related to delays in the Charlotte blizzard.
The delays involved flights operated by both American Airlines' predecessor US Airways and its regional partners.
The Transportation Department says the airline didn't do enough to prepare for that scenario. The department does allow exceptions to its tarmac rule for safety, security, or air traffic control-related reasons.
"Our tarmac rule is meant to prevent passengers from being trapped in aircraft on the ground for hours on end," U.S. Transportation Secretary Anthony Foxx said in a statement.
A $1.6 million fine was slapped against Southwest Airlines (LUV) in 2015.
