The AQR ranked the 10 major airlines as follows for 2000: 1) Delta, 2) Alaska, 3) Southwest, 4) U.S. Airways, 5) Northwest, 6) American, 7) Continental, 8) TWA, 9) United and 10) America West.

The AQR is a summary of month-by-month quality ratings for major domestic U.S. airlines

Does this mean I need to hold my breath while flying AW, United, or TWA? <g>

Don't worry about your air quality Doug, you'll have plenty of fresh air riding in the open cockpit of the bi-plane, during your return flight from Las Vegas. LOL
Either that of fresh air will be yet another UP-charge for you. You might want to buy that one! <VBG>