The post merger CASM (that of the NEW USAirways) is higher than the CASM of AWA. Simple subtraction will yield the impact of the inefficiency of the OLD USAirways.
AWA relied on productivity and efficiency to generate profits where airlines such as US could not. Now the higher costs are making it difficult if not impossible to make profits in those very same markets. Think of it as the Titanic Effect.
No....lets call it the "Phoenix is an economic wasteland effect"