The US Army transport ship USAT Meigs found an oil slick along the course of the lost aircraft about 500 miles from Manila, took samples, and stood by to investigate.[1] Search for the plane was called off on August 5, 1938.[3] Later tests on the oil samples collected by Meigs indicated no connection with the aircraft.[4] Modern reviews of the events and oil sampling techniques have led some to conclude the test of oil from the tropical Pacific compared to samples from San Francisco were not conclusive in ruling out a link with a slick found close to the last estimated position allowing for ocean currents.[5]