US airlines saw a sharp drop off in the number of long delays and canceled flights in December, as mild weather helped get passengers to their destinations on time through the peak holiday travel season.
It capped off a year of improving results for US airlines, which benefited not only from clearer skies but also from fewer flights, giving the remaining ones better odds of being on time.
The Transportation Department said Tuesday that 84.4 percent of flights arrived within 15 minutes of their scheduled time. And just 0.8 percent of flights were cancelled. That's about 3,700 out of nearly 500,000 flights. Those are both better rates than any December since DOT started collecting data 17 years ago.
While flights were more often on-time than a year ago, the rate was still lower than in November. That month, 85.3 percent of flights were considered on time. AirTran Airways, owned by Southwest Airlines Co., beat out long-time leader Hawaiian Airlines for the highest on-time rate at 91.5 percent. The overall number of cancellations went up from November's 0.7 percent.
There were no tarmac delays of more than 3 hours for U.S. airlines. There was one lengthy delay of an international airline.
More delays were caused by late-arriving aircraft, maintenance and crew issues during the month than in November. If one flight is late, it can cause a ripple effect across an airline's network.
There were only two flights that were considered chronically delayed for two consecutive months in December. They were both ExpressJet flights between Reagan Washington National and Newark Liberty in New Jersey.
Airlines lost or damaged fewer bags in December compared to a year earlier, but more than in November. The rate for mishandled bags in 2011 went down from the year before. The number of bumped passengers also fell.