SHANKSVILLE, Pa. — Families of Flight 93 have sealed a deal on a postage-stamp-size parcel that would be the first tract bought for a memorial to the 40 people on board the United Airlines jetliner when it slammed into the ground near here Sept. 11.

The purchase of the three acres — only a fraction of the 2,200 planned for the Flight 93 Memorial park — is largely a symbolic gesture. But to many it is a sign that, at long last, the acquisition of land to honor the passengers and crew who thwarted an attack on Washington is gaining momentum.

"This is a first small step in what will be the larger picture of getting the balance of the acreage," said Larry Catuzzi, whose daughter Lauren Grandcolas was aboard the plane.

Supporters have overcome opposition to the park's size and cost, but federal funding has yet to flow to the National Park Service, which is overseeing the site's creation. A powerful House member from North Carolina blocked federal funding for the land for three years before dropping his opposition.

But park proponents still face other hurdles — unwilling sellers, negotiations over mineral rights, and environmental hazards from decades of coal mining at the site.

If all goes on schedule, the park will open in 2011, the 10th anniversary of terrorist attacks. The centerpiece is the memorial itself, set in a 400-acre natural "bowl" atop a mountain. Plans include a black slate plaza and a grove of 40 maples.

The park would be surrounded by 1,800 acres of protected land, mostly woods, fields and farms.

The start-up costs are estimated at nearly $60 million, about one-third of that for the land.

"We are still awaiting the federal funding," said Joanne Hanley, superintendent of the Flight 93 Memorial. "The negotiations with landowners are in different stages, but we have to have money to move forward."

The $10 million federal request for land acquisition was contested by U.S. Rep. Charles Taylor, R-N.C., chairman of the Appropriations subcommittee on interior, environment and related agencies. Under intense public pressure, Taylor dropped his opposition in June. But Congress has yet to vote on the request for the project's first $5 million installment.

The Families of Flight 93 group decided to move forward on its own this summer, using a portion of the $1.2 million it received from the opening weekend box office receipts of the movie "United 93" to buy the three acres.

Patrick White, whose cousin Louis J. Nacke II died in the crash, said the group was on track to close on two larger parcels this fall.