CHICAGO - International airline passengers on edge about making their connections when their flights into the United States are late may have reason to relax when they are headed to Chicago and New York, where federal authorities are using new procedures to help travelers bypass long, snarled customs lines.

The program, first introduced at Chicago's O'Hare International Airport and then at John F. Kennedy International, is designed to be proactive.

As soon as an airline knows a plane is late, sometimes even before it takes off for the United States, staff scan passenger lists to see who has a connecting flight and when. They flag those passengers who look as if they may be in danger of missing their connections. Once the plane lands, gate attendants hand them bright-orange cards that allow them into the short, fast-moving customs lines.

At a time when Homeland Security officials are facing criticism for introducing full-body scanners, enhanced pat-downs, and other measures that raise passenger anxiety, the new program enables authorities to argue that they are also taking steps to make the airport experience less stressful.

The program dubbed Express Connection is saving airlines millions of dollars they otherwise would spend rebooking passengers who miss connecting flights. "It's a win-win situation for everybody," said Kathleen Guerrero, customer-service manager at O'Hare.

The program could be introduced at other major U.S. airports with large numbers of international flights. Los Angeles and Seattle-Tacoma are among those expressing interest.

"You feel so vulnerable and violated when you miss a flight," said Brian Bell, a Chicago spokesman for the U.S. Customs and Border Protection agency. "We all get beaten up - us, the airlines - when people are missing flights."

JFK began developing Express Connection several months after O'Hare and is using it at just two terminals, said John Saleh, a spokesman for Customs and Border Protection. "This is still in our infancy with us," he said. "Eventually we want to include all airlines and all terminals."

Since the program was set up at O'Hare in June, about 16,500 incoming international travelers who might have missed a connecting flight did not, according to figures cited by Larry Di Giannantonio, assistant port director at O'Hare.

That translates into big savings for airlines: On average, they lose $150 whenever someone misses a flight, so the number of travelers who did not miss flights at O'Hare amounted to a combined savings of about $2.5 million over the six months, he said.

On a recent afternoon at O'Hare's customs checkpoints, more than 300 people were corralled in regular lines. The express lanes for those on late-running flights had only a few travelers. Those with Express Connection cards at O'Hare take an average of 23 minutes to get through customs, while the regular lines normally take close to an hour.

O'Hare officials say Express Connection has been comparatively easy and cheap to implement, requiring no new infrastructure or additional staffing.

Several transportation analysts give the project a thumbs-up. "This helps avoid those extremely awkward moments where desperate passengers have to beg for special attention, which adds stress to the whole airport environment," Joseph Schwieterman said.