SEATTLE — A plane on the drawing boards at Boeing Commercial Airplane Co. is so big that many airports would have to rebuild terminals to handle it.
Boeing representatives say the plane, called the 747-500, is still no more than an artist's sketch and has no official measurements.
But unconfirmed reports say the plane would be longer and wider than the 747-400, the world's largest commercial airplane.
With a wingspan estimated at between 240 and 280 feet, it would be 30 to 70 feet longer than the 747-400.
News that Boeing is considering the plane surfaced recently at the Farnborough Air Show in England.
The goal of the new plane is to fly farther with more people, if that's what airline customers want, said Boeing spokeswoman Elizabeth Reese.
The company is considering the huge plane for the late 1990s, Reese said.
But at a recent meeting of the Airport Operators Council International in Denver, airport operators sent a message to Boeing saying they don't want a larger plane.
The 747-400 already is clogging some airports, said Elizabeth Tubbs-Stevens, business planner with the Seattle office of Leo A. Daly Co., a planning and engineering firm that helps airports allocate space for planes.
Many airports don't have gates that can accommodate the larger jets, and those that do may only have a few.
The 747-400 has wing tips that fold up to reduce is wingspan, but those wing tips create a vertical clearance problem, said Bob Small, director of Daly's Seattle office.
The larger plane on the drawing boards would be a worse problem, Small said. Airport operators wouldn't want to rebuild hangars and redo taxiways to accommodate it, he said.
But Reese said airports, like aircraft, change with time.
"Airport operators are looking at present-day airports," she said. "Everybody has to think ahead."