DOT cited the carrier for 13 violations at Chicago-O'Hare International Airport on July 13, 2012, as "severe thunderstorms and lightning caused several ramp closures." In assessing its largest-ever fine since
enacting tarmac-delay rules in April 2010, DOT ordered United to remit $475,000 to the government, with the remainder allocated to "mitigation measures for affected passengers and significant corrective actions by United to enhance future compliance with tarmac delay requirements." According to DOT, "Delays by United and its United Express code-share affiliates exceeded the three-hour limit for tarmac delays by as little as two minutes and as much as 77 minutes."