I finally started playing around with KPHL. The 200 US Air flights are actually Piedmont (PDT) flights. Both airlines are in the xxxx_airlines.txt file with the IATA code of US. To avoid confusion US Air (AWE) either needs to be removed or commented out (//). Then when US/PDT shows up in the sim you'll see it in the American Airlines livery as expected. So, although the schedules could still use a refresh it's not as bad as we thought.