More US flights arrived late in June than the month before, continuing a string of poor performances by the nation's airlines.
The government says that in the first six months of the year, the rate of late flights was the highest since 2008 and cancellations were the highest since 2000.
The US Department of Transportation said Thursday that among airlines reporting figures, 71.8 percent of domestic flights arrived on time in June, down from 76.9 percent the month before and 71.9 percent in June 2013. A flight counts as late if it arrives more than 14 minutes behind schedule.
Hawaiian Airlines and Alaska Airlines, which aren't as exposed to bad weather in the eastern and central parts of the country, had the best on-time ratings. Delta Air Lines led among the biggest carriers.
Regional airlines Envoy and ExpressJet and big carriers Southwest and American were at the bottom of the rankings. All were late more than 30 percent of the time. American and Envoy are both owned by American Airlines Group Inc., whose chief operating officer, Robert Isom, said that the company's network suffered more than rivals from bad weather.
About 2 percent of all flights in June were canceled, with Envoy, ExpressJet and SkyWest faring the worst. Delta, Hawaiian, Frontier, Virgin America and Alaska all had minuscule cancellation rates of 0.2 percent or lower.
Jean Medina, a spokeswoman for Airlines for America, a trade group for the large carriers, said weather has been the biggest factor all year, with 17,370 weather-related cancelations in the first half of 2014 compared with 11,480 in the same period last year.
"With the exception of April, every single month had worse weather-related cancellations than the year earlier ... there were times it was simply not safe to fly," Medina said.
For the first six months of 2014, 74.2 percent of flights by the reporting airlines were on time. That is the fifth-lowest mark for the period in the last 20 years and the lowest since 2008 and 2007.
Consumers filed 1,095 complaints with the government against U.S. airlines, an increase of 16 percent over June 2013. Hawaiian, AirTran, Southwest and Alaska had the lowest rate of complaints, while Frontier, United and US Airways had the highest.