The
DOT press release includes the following.
United is also being fined $750,000 for five lengthy tarmac delays that took place at Chicago O’Hare International Airport on December 8, 2013 and one lengthy tarmac delay of a flight that was diverted to Houston Hobby Airport on May 20, 2015.
Were any flyertalk folks on the 2013-12-08 flights at ORD or the 2015-05-20 flight that ended up at HOU? The press release notes these tarmac delays were in excess of three hours. Is three hours the threshold to trigger a fine?