The Prince George's County Planning Board gave unanimous approval yesterday to the billion-dollar PortAmerica development and its controversial 52-story office tower, pushing the Potomac shoreline project past one of the major hurdles before construction.

The massive project's site plan must still gain County Council approval. Council members, who voted in favor of the zoning changes for the project, have been highly supportive of the development, which would include 1,200 housing units, shops, a hotel and waterfront promenade. PortAmerica, proposed for just south of the Woodrow Wilson Bridge, would also contain 1.7 million square feet of office space and a 500-boat marina.

"It is a terrific opportunity to put Prince George's County on the map," said council member Jo Ann T. Bell.

Members predicted smooth passage through the council. A date for consideration has not been set.

PortAmerica developer James T. Lewis said yesterday that the approval "has been a long time coming. I'm very pleased and gratified." He said he hopes to begin construction by fall.

In approving the project, Planning Board members dismissed recent protests from two federal commissions and an airline pilots association about the height of the office tower, which would be the tallest building between New York and Atlanta.

The issue of flight safety is pending before the Federal Aviation Administration. An FAA spokesman said yesterday that the agency could not halt construction of the building, but that a determination that it posed a safety hazard would make the structure uninsurable.

The Planning Board expressed confidence that the $175 million, glass-sided World Trade Center and the surrounding complex would bring economic development, visitors and a new, glittering image to the county.

"I'm most happy it's on the Maryland side of the river," said Planning Board Chairman John W. Rhoads. "People will go there and people will come away with a sense of pride."

PortAmerica, which Rhoads compared to Baltimore's thriving Harborplace, comes in addition to another billion dollars in development projects approved recently in Prince George's.

They include the Bowie New Town Center and the Maryland Science and Technology Center, also slated for Bowie.

In the 10 years since it was originally proposed, the PortAmerica idea went through several hands before being taken over by Lewis. The proposal has raised substantial controversy, most recently over the height of the office tower.

Last week, the Air Line Pilots Association told planning officials that the tower would pose a safety hazard for flights to and from Washington National Airport.

In addition, the National Capital Planning Commission, which oversees federal interests in the Washington area, the federal Commission of Fine Arts and the National Park Service have denounced the tower, saying it would overwhelm the Washington Monument and the capital skyline.

As evidence of their concern, opponents displayed photographs depicting the tower as clearly visible from the White House and other scenic spots. But Bell rejected those arguments yesterday, saying: "How neat. The president of the United States will go out on the back porch and say, 'Ah yes, Prince George's.' "

Opponents of the project criticized yesterday's action.

"The people have lived there and enjoyed the view. You're going to take it all away," said James F. Vance, the attorney for Oxon Hill residents opposed to the plan.

Marie W. Lee, who told the board she would have a view of a "long, solid row of the backs of buildings" if PortAmerica is built, raised concerns about traffic, the effect on wildlife and the impact on a nearby historic cemetery.

But Rhoads said those objections did not outweigh the benefits of the project. "That is part of what happens as progress moves into an area," he said.

Others, including County Executive Parris Glendening, praised the board's approval.

"It's probably one of the most important projects in America today," said County Council Chairman William Amonett.

In voting to approve the project, the Planning Board included several conditions the developer must fulfill to gain approval at later stages, when more specific plans must come before planning officials.

Among the conditions is a requirement that the developer try to build the tower so it does not "severely impact" the view from Oxon Hill Manor, a historic mansion in the area.

The plans allow slight movement of the tower, planning staff members said.