 The training and intense watching bore dramatic fruit in the autumn of 1943 when observers at a post in West Palm Beach, Florida, saw and reported instantly the passage of a German aircraft bearing American markings over their post.The fact that the plane was one that had been captured in Europe and was being flown back to this country for examination detracted not one bit from the effectiveness of the recognition instruction.At the peak of operation, the Aircraft Warning Service of the First Fighter Command numbered some 750,000 individuals, of whom about 12,000 were in information and filter centers.