Airlines' on-time arrival rate hits 84.3%

— -- The nation's largest airlines have been on a streak lately of getting passengers and their bags to their destinations on time at record-high rates.

In the first five months of this year, they've had the highest on-time arrival rate — 83.4% — for any such period in the 18 years that the Transportation Department's Bureau of Transportation Statistics has been recording data.

The rate of canceled flights for the five months, which was 1.07%, also was the lowest in the last 18 years, according to data released Tuesday.

But travelers shouldn't be lulled into thinking that airlines have entered a new era of consistently fewer delays, analysts say. The airlines are just a bad thunderstorm, hurricane or blizzard away from canceling thousands of flights.

Fliers need to look no further than last year, when a February blizzard crippled New York, which has the busiest airspace in the United States. The snowstorm resulted in thousands of flights being canceled. Airlines had barely recovered from that when Hurricane Irene pummeled Washington, D.C., and the Northeast in August.

The result? From January to August of last year, airlines were on time just 77.2% of the time, down from 79.2% for the same stretch in 2010.

Any time storms hit the busy Northeast corridor, planes all over the U.S. are ordered to stay put in their departure cities or slow down if they're already in the air, says Greg Zahornacky, assistant professor at Embry-Riddle Aeronautical University.

When the derecho thunderstorm struck the Midwest and Mid-Atlantic region on June 29, only 66.1% of flights were on time at the five major airports in the states that declared a state of emergency that day, including Washington's Dulles and Reagan National airports. That's compared with 78.9% for the first 28 days of the month, according to FlightStats, which keeps track of more than 150,000 flights a day

Another factor working in favor of the airlines' current streak is that they have fewer planes in the air. Airlines have cut back on flights to save on jet fuel costs and keep planes full. Less air traffic should mean fewer delays.

"We're not clogging the skies," says Mike Boyd, president of the Boyd Group, an airline consulting firm. "Secondly, we have a situation in which there wasn't much in terms of weather. Why are 16% of flights arriving over their 15 minutes?"

Airlines acknowledge that good weather and fewer flights have contributed to their eighth-consecutive month of better on-time arrivals and bag handling.

"Mild weather has helped, as have operations that are focused on getting planes that are often full during the busy summer travel season out on time," says Nicholas Calio, president and CEO of Airlines for America, which represents the industry.

But he also says airlines are improving their operations and focusing "on what matters most to customers: arriving safely on time and with their bags."

Airlines posted an on-time arrival rate of 83.3% in May, up from the 77.1% rate in May 2011. It was, however, a slight dip from April's rate of 86.3%. Airlines canceled 0.9% of their domestic flights, down from the 2.1% cancellation rate in May 2011 and the 1% rate in April.