Though it is clear that the legacy carriers and the cargo guys have higher numbers of pilots per plane than the National/Regional carriers. FWIW... Southwests number is 11 pilots per aircraft more in line with the smaller carriers than the legacy's. And certainly without the additional info that HSLD spoke of its not a complete statistic, but it certainly shows trends within types of carriers. I suspect the higher crew numbers for the mainline carriers is due to their international flying and the requirement to have crews in crew rest for extended periods of time in international destinations.