ATLANTA — The board overseeing planning for a new Falcons stadium in downtown Atlanta gave the thumbs-up Tuesday to a design that invokes the giant bird's wings and would feature enormous windows showcasing views of the city. The approval from the Georgia World Congress Center Authority's board of governors clears the way for the 360 Architecture firm to create a detailed schematic plan. The board also must sign off on that plan, which is expected to be finalized in April 2014.