How long do you have to think about it before you decide to give away $60 million?

If you are Steven F. Udvar-Hazy, the answer is exactly five minutes.

Yesterday the Hungarian American businessman made the Smithsonian Institution's largest gift official. To explain why he's doing it, he talked about a sunny Sunday in May 1953 when a small boy went to an air show in Soviet-occupied Hungary.

"This 7-year-old boy sees the sunlight reflecting from the polished aluminum skin of a Yak fighter plane. He sees the contrails of a MiG-15 jet with a red star on its side. He sees propellers starting, and hears the noise and excitement of roaring airplane engines," he said yesterday in an address to the staff of the National Air and Space Museum, where his donation will help build a sprawling annex at Dulles International Airport.

"He looks skyward, and sees airplanes climbing into the air, leaving the grass runway behind," Udvar-Hazy continued. "There are soldiers and guards standing everywhere, but their importance is overshadowed by the sudden spirit of freedom, and the feeling that an airplane rising into the sky is the hope, the only way to reach into a bigger world, a world representing his future."

Living in Hungary felt like being a prisoner, he said. When he was 12, his family escaped to Sweden and reached New York in 1958.

Now Udvar-Hazy, 53, has a life that revolves around every aspect of aviation. He is president and CEO of International Lease Finance Corp., the world's largest lessor of commercial aircraft. The company, based in Beverly Hills and now a subsidiary of American International Group Inc., owns 400 jets worth more than $18 billion. He has the kind of personal wealth that enabled him to pledge the money quickly when the Smithsonian came calling.

"The time has arrived for my family to give back to America part of the rewards that aviation has been instrumental in creating" for him," said Udvar-Hazy, a slight man with thick reddish-brown hair and a mustache. Speaking from neatly printed notes, his voice filled with emotion as he stood near Charles Lindbergh's Spirit of St. Louis, the Wright Brothers' 1903 Flyer and the Bell X-1 ("Glamorous Glennis") that Chuck Yeager used to break the sound barrier in 1947.

The $60 million gift allowed the museum's officials to announce the Air and Space capital campaign nine months earlier than planned. The money will help underwrite construction of a 710,000-square-foot complex that has the working name Dulles Center. I. Michael Heyman, the outgoing Smithsonian secretary, said it was up to the institution's Board of Regents to decide if the facility would be named for Udvar-Hazy.

But Udvar-Hazy said he wasn't interested in a monument to himself: "That is really not the motivation."

The money is being drawn from his family foundation and personal funds, and he said it didn't take long to figure out how much. "The amount was easy, it was more just what they needed once we understood the scope of the project and the fact that the federal government has a limited capability right now to fund these types of programs," he said.

The center, which is four miles from the main terminal at Dulles International Airport, will house many of the larger aircraft and spacecraft that won't fit in the museum on the Mall. The design, by architect Gyo Obata, was inspired by an airplane hangar. It will have ample room for 200 historic aircraft and 100 space artifacts that have never been in a museum, including an SR-71 Blackbird reconnaissance aircraft, a B-17 Flying Fortress, the Enola Gay (the B-29 that dropped the atomic bomb on Hiroshima) and the space shuttle Enterprise. The new complex will probably cost $200 million, officials said yesterday.

Besides private dollars, the center is receiving $34 million from the state of Virginia. Construction costs will be $130 million, $90 million of which has been raised.

"I think the momentum is just enormous that comes from this gift and also the help Steven Hazy is going to give us," said Heyman. The museum is expected to open by December 2003.

Udvar-Hazy has already agreed to work on the rest of the fund-raising drive. He explained bluntly that he has a lot of clout in the aviation industry.

"Our company is the largest purchaser of commercial jet airplanes in the world. We are the largest customer of Airbus, and we purchased 600 new jets from Boeing since 1977. Along with dealing with those companies, we have very strong relationships with all the major suppliers. . . . Those companies undoubtedly will be called upon," he said. "At least they should match what I have done."

In addition to his business career, Udvar-Hazy has been a pilot since 1968, with 6,000 hours of flying time. Yesterday he was an hour late for the meetings at the museum because his Gulfstream IV had to fight through strong headwinds en route from Paris.

"It was a combination of headwinds flying from Paris and our antiquated air traffic control system, which had us about halfway to Charleston, S.C.," for the approach to Reagan National, he said. He wasn't the pilot for the trip to Washington, but after yesterday's program, he said he planned to take the controls for the flight to California.

CAPTION: Steven Udvar-Hazy said his lifelong love of flight inspired his $60 million gift for the Dulles museum.