He is right as far as he went with it (which was barely scratching the surface) - if US flew...oh, say DL's route network with US' contracts and fleet, US' CASM would be different than that reported. Like always, though, the devil is in the details and the details are all the other differences between carriers other than stage length. Stage length is the easiest factor to correct for - not that it's easy but just the easiest - which is why the analyst' adjust only for it.
US obviously couldn't fly DL's network with US' fleet because 1- US doesn't have enough airplanes, and 2- US doesn't have the right mix of airplanes even if you doubled (or whatever multiple it would take) the number of each type plane. Other factors are the fleet mix as mentioned - a higher percentage of big airplanes generally flying long legs means lower CASM if everything else is equal. Fuel prices aren't equal for all airlines - where it's bought and hedging (either successfully or unsucessfully) play a part. Facilities cost aren't equal across all airports. The efficiency of the operation isn't equal. Productivity, influenced by the operation and contracts, isn't equal. The list goes on and on, and that's before even mentioning the low cost carriers with their operational advantages.
Finally, something that usually doesn't show up (at least for all carriers) is system CASM - the CASM for all branded operations. US has the largest percentage of ASM's flown by express carriers (although once Republic has their Frontier/Republic/Midwest operations sorted out they may take the lead). That means that US has a higher percentage of higher cost Express ASM's than any other carrier. Let's face it - mainline CASM doesn't mean a thing for a GSO-PHL flight on a CRJ or E-170/175.
Of course, Kirby (and the analysts) know all this but it doesn't get mentioned except a few places - the MIT Airline data project and Airline Financials, both of which take the raw BTS and SEC filings data and boil it down to a simple format.
A perfect example of how a valid fact can distort reality is to compare WN and US. Listening to Kirby one would think that all that's needed is to adjust for stage length. However, WN had the shortest stage length in the industry, so that adjustment would increase the difference between US and WN's CASM. It's all those other factors that allow WN to pay what they do and still have the lowest stage length adjusted CASM in the industry. Of course, it one mentioned that to Kirby he's quickly say that you can't compare US to WN since the operational models are so different, thus admitting that there's a lot more to CASM differences than stage length.
Jim
