Sen. Amy Klobuchar and Iron Range Democrat Jim Oberstar, chairman of the U.S. House Transportation and Infrastructure Committee, visited the Gulf oil spill zone Friday as part of a congressional delegation. The group flew over the oil slick in a Coast Guard plane to give them a view of the extent of the spreading environmental disaster. Spokesman John Schadl said Oberstar was already in Louisiana for a Canada-United States Inter-Parliamentary Group convention. Oberstar's wife, Jean, a New Orleans native, accompanied him on the trip. Once the causes of the BP oil rig explosion are known, Oberstar's committee might play a role in finding ways to avoid another similar catastrophe in the future, Schadl said.