 Pan American officials expressed confidence that if the plane had been forced to land in the ocean and the fuselage had not been punctured, the craft could stay afloat "almost indefinitely".The most promising sign during the search was that three pilots reported hearing faint radio distress signals from a hand-operated emergency radio similar to the type that would have been taken aboard life rafts.The signals were heard on the 500 kilohertz distress frequency at the Coast Guard station at Upolu Point on the island of Hawaii.