PITTSBURGH — The owner of the land where United Airlines Flight 93 crashed in the Sept. 11, 2001, terrorist attacks reached an agreement Friday to sell the parcel, clearing the way for the development of a memorial.

The National Park Service, Families of Flight 93 and land owner Svonavec announced the deal for the 274 acres in Shanksville in a joint statement.

The agreement gives the National Park Service access to the land, including the site where the plan crashed, and allows for the planning and construction of the memorial.

The three also agreed to let a court determine the value of the land. Patrick White, vice president of the Families of Flight 93, and Patrick Svonavec, the attorney for Mike Svonavec, the treasurer of the quarry company, characterized the deal as an amicable condemnation.