PORT-AU-PRINCE, Haiti – A major obstacle to delivering aid to Haiti began to be cleared Friday, as the U.S. Air Force brought order to the chaotic Port-au-Prince airport.

In another sign of progress, the aircraft carrier USS Carl Vinson took up position off Haiti's coast and began to fly water and other badly needed supplies to land. Despite these and other advances, hundreds of thousands of Haitians remain stranded in dire conditions.

Earlier,...