Runway construction at Atlanta's airport, which FAA says requires expansion. (Photo courtesy of Hartsfield-Jackson Atlanta International Airport)

Although overall U.S. aviation passenger volume has yet to return to levels seen before the Sept. 11, 2001, terrorist attacks, five major domestic airports require additional capacity now, the Federal Aviation Administration says.

In preliminary results disclosed March 25 from an unfinished aviation capacity study, FAA says airports in Atlanta, Newark, and Philadelphia, as well as New York's LaGuardia and Chicago's O'Hare need more capacity. The agency adds that a total of 16 airports will require expansions in 2013 unless moves are made in the meantime to deal with projected demand.

FAA's annual aviation forecasts, released the same day, show that overall U.S. passenger enplanements won't return to pre-9/11 volume until 2005. The agency says that U.S. passenger volume should climb 7% this year, to 686.7 million, but that's still slightly below the 2001 total of 683.4 million. Transportation Secretary Norman Mineta said, however, that 10 of the 35 largest U.S. airports now are operating at pre-9/11 levels.

In another measure that affects airport construction plans, FAA says total aircraft operations--takeoffs and landings--should increase 3% in 2004. But that's still 3% below the 2001 mark.

Mineta also observed that since 2000, when the aviation system was hit with congestion and delays, "We have poured a lot of concrete, added new runways" and expanded infrastructure.