Flight delays are increasing on major U.S. airlines, but fewer travelers are complaining.
The federal Department of Transportation said Tuesday that just 68.9 percent of domestic flights arrived within 14 minutes of schedule in December, compared with 76.6 percent a year earlier. Cancelations rose too.
In early December, snow, ice and freezing temperatures snarled operations at big hub airports in Chicago and Dallas, causing thousands of canceled flights and delays that rippled across the nation.
There were 10 flights during the month that were stuck on the ground for at least three hours, in violation of federal rules, and nine occurred at Chicago's O'Hare Airport on Dec. 8.
The airlines, however, were struggling to stay on schedule even before then. For all of 2013, the on-time rate fell to 78.3 percent, a drop of 3.6 percentage points from 2012.
The government figures cover 16 airlines including all the giants and the leading regional carriers, but they may underestimate the delay problem because they capture only three-fourths of domestic flights at U.S. airports, according to a recent report by the Transportation Department's inspector general. Small but growing carriers such as Spirit Airlines and Allegiant Air aren't included, and airlines don't always indicate why a flight was late.
The statistics also make it harder to compare one airline's performance to another. Flights on smaller planes are more likely to be canceled or delayed. Those planes are often operated by regional carriers on behalf of major airlines.
So if a Delta Connection flight operated by a regional carrier is canceled or delayed, "Delta doesn't take the hit for that in the DOT report," said Edmund Otubuah, an executive at aviation-data firm masFlight. "It doesn't tell the full picture."
Flawed or not, the government's figures showed Hawaiian Airlines in its customary spot at the top of the rankings — good weather in the Pacific helped. Among the biggest airlines, Delta and US Airways had the best on-time ratings while Southwest Airlines had the worst — nearly half its flights were late.
Steve Hozdulick, Southwest's senior director of operational performance, said that for several months Southwest has been putting more flights into peak hours when customers want to fly. That resulted in tight schedules, and if the airline fell behind, delays cascaded through the rest of the day, he said. Southwest is going back partly to its previous approach and will "loosen up" on schedules, he added.
Airlines canceled 2.9 percent of their domestic flights in December, up from 1.6 percent a year earlier. Airlines, which have faced potential fines for long delays since 2011, increasingly cancel flights when they expect bad weather or other challenges. Jean Medina, a spokeswoman for the industry trade group Airlines for America, said that approach reduced hardship on travelers — they were less likely to be stranded at an airport.
Few of those displaced passengers bothered to file complaints with the government. The Transportation Department said that complaints fell 14.1 percent last year, to 13,168 out of the millions of people who boarded a plane.
David Koenig can be reached at http://www.twitter.com/airlinewriter