CHICAGO — Alarm in the aviation industry over a projected 10 percent drop in domestic flights this winter hasn't derailed the opening of multimillion-dollar runways at three U.S. airports on Thursday.

CHICAGO — Alarm in the aviation industry over a projected 10 percent drop in domestic flights this winter hasn't derailed the opening of multimillion-dollar runways at three U.S. airports on Thursday.

Despite global economic woes that have fewer people taking to the skies, airport officials in all three cities are heralding the new capacity as crucial to alleviating congestion and delays, especially in the long term.

They say that's well worth the more than $450 million spent on the runway at Chicago's O'Hare International; the approximately $350 million spent at Dulles International, just outside of Washington, D.C.; and the more than $1 billion for Seattle-Tacoma International.

"This is absolutely critical, absolutely necessary, absolutely money well spent," said Rosemarie Andolino, who leads the ongoing $15 billion expansion of O'Hare, a vital global hub inaugurating its first new runway in nearly 40 years.

Others call new runways a positive step but no cure-all for chronic delays.

"The greater challenge will be to do something about modernizing air space so that those improvements in efficiency on the ground is matched in the air," said David Castelveter, a spokesman for the Air Transport Association, which represents U.S. carriers.

The association backs a Federal Aviation Administration push for a new satellite-based network that would let planes fly using GPS, instead of radar, though funding and implementation issues have hampered the $30 billion project.

Meanwhile, nationwide bottlenecks, particularly around chronically clogged New York City-area airports, will continue hampering delay-reduction efforts, Castelveter predicted.

Air traffic controllers have expressed concern that the new runway at Dulles — the first since the airport opened in 1962 — won't improve operations because taxiways needed to make it fully functional have not yet been built.

The FAA acknowledges that new runways aren't the sole solution, noting in a 2007 report that just two major U.S. airports have opened in the past 40 years — Dallas-Fort Worth and Denver International — and that as many as four need to be built in the next two to three decades.

But with U.S. Transportation Secretary Mary Peters set to visit all three locations Thursday, federal aviation officials are using the runway openings as a chance to celebrate in an otherwise bleak period for the air travel industry.

Runways typically take more than 10 years to plan, approve and build. Despite current downturns — data show domestic flights fell 6 percent in August — air travel still is expected to rise from the approximately 700 million air travelers in 2007 to more than 1 billion annually during the next decade.

O'Hare — with more than 900,000 takeoffs and landings a year, second only to Atlanta's Hartsfield-Jackson International — is expected to handle an additional 300,000 flights annually by 2018, an increase the new runway should help to accommodate.

"You can't suddenly decide in 2018, 'Oh shoot, we need more runways, let's hurry up and get them done next week,' " Andolino said.

Synonymous with air-travel angst for decades, O'Hare's delays persist despite a more than 8 percent fall in traffic this year. Mother Nature has been the airport's main vulnerability because when bad weather reduced visibility, controllers could land just two planes at a time — reducing capacity by a third.

The new strip allows controllers to bring in three planes at once no matter the conditions.

"The single biggest benefit is that it makes O'Hare a viable, all-weather airport," explained Joseph Schwieterman, a transportation expert at DePaul University. "We can put to rest the traffic meltdowns that came every few weeks whenever the skies turned dark."

O'Hare should immediately be able to handle an additional 52,000 flights annually with the new runway.