Summer air-travel forecast: Easier, on time?

— -- Travelers this summer can expect recent record airline delays to ease as sharp cuts in flight schedules reduce congestion across the nation, according to federal data and aviation experts.

Airlines cut schedules by 8-10% in September. On-time performance has improved significantly in all but one month since then, according to federal Bureau of Transportation Statistics data. The two years prior to September 2008 saw record-breaking flight delays.

From September to February, the most recent period available, 80% of flights arrived within 15 minutes of their scheduled time. In the same period a year earlier, 74% of flights were on time.

Even with the improvements, airlines and federal aviation managers are girding for the usual disruptions that occur when thunderstorms block normal flight routes.

Nancy Kalinowski, the Federal Aviation Administration's vice president for air-traffic operations, said the agency has opened new flight routes for spring and summer in the New York region in an attempt to stem delays during bad weather.

Despite the reductions, New York City's three congested airports could trigger delays that ripple through the aviation system — particularly when thunderstorms hit the area.

The New York region, with Newark Liberty International, John F. Kennedy International and LaGuardia airports packed closely together, is particularly susceptible to weather complications because its clogged airways allow limited flexibility for rerouting planes, Kalinowski said.

"It's becoming more and more clear that the key constraint in the system right now is New York," said John Hansman, an aviation professor at the Massachusetts Institute of Technology. "That's where most of the problems are going to center over the summer, and there will be some bad days."

In January and February, only 59% of flights arrived on time in Newark, despite federally imposed flight reductions at the airport last year designed to reduce delays, according to federal data.