Nearly a quarter of U.S. flights late in April

Nearly a quarter of domestic airline flights arrived late to the gate in April as severe thunderstorms shut down major hubs, federal data released Tuesday shows. The 16 airlines required to report operational results to the Transportation Department recorded an overall on-time arrival rate of 75.5% in April. That's down from 85.5% a year ago and from March's 79.2%, the monthly report from the department's Bureau of Transportation Statistics says. A flight is considered on time if it arrives within 15 minutes of schedule. Storms ripped through the nation in April and forced airlines to hold or cancel flights in key hubs such as Atlanta, Orlando and Chicago. Other factors that contribute to delays — late-arriving aircraft, aviation system delays and maintenance problems — also worsened in April, the report says. Flight cancellations rose in April from a year before, with 2% of scheduled flights — or 10,100 out of 507,000 — called off. In April 2010, only 0.7% were canceled. "We attributed the downturn in on-time performance and the spike in cancellations to the weather pattern that spawned tornadoes in the South and Midwest and thunderstorms in the Northeast," says David White of FlightStats, which monitors air traffic. Weather favored carriers with operations concentrated in western and northern regions, FlightStats noted in its April report. Hawaiian Airlines, which flies mostly among the islands, delivered more than 94% of flights on time and claimed its usual top spot in on-time performance. Seattle-based Alaska Airlines followed with 89.5%. ExpressJet, which operates as a feeder carrier for United and Continental, scored the lowest with 68%. JetBlue came in next to last, with 68.4%. Despite severe weather, only four planes were stuck on a tarmac for more than three hours in April. Three were Delta flights in Atlanta on April 27, when wind and thunderstorms forced numerous cancellations at the world's busiest airport. In late April last year, the Transportation Department began enforcing a rule that imposes fines up to $27,500 per passenger for flights that sit on the tarmac for more than three hours without allowing passengers to disembark. Since then, only 20 tarmac delays of more than three hours were reported from May 2010 through April this year. That compares to 693 in the comparable period a year earlier. Transportation Secretary Ray LaHood trumpeted the improvement Tuesday. "On the one-year anniversary of the tarmac-delay rule, it's clear that we've accomplished our goal of virtually eliminating the number of aircraft leaving travelers stranded without access to food, water or working lavatories for hours on end," he said. "This is a giant step forward for the rights of air travelers." In opposing the rule, airlines warned it would trigger more cancellations, saying carriers would rather cancel a flight than face onerous fines, especially during bad weather and busy holidays. Other findings from the report: •More mishandled bags.  The carriers posted a mishandled-baggage rate of 3.24 reports per 1,000 passengers in April, up from April 2010's rate of 2.84 but down from 3.32 in March.