Sustainable growth also meant growth that was driven by sales--not one-time gains or cost-cutting measures.

FORBES

Private researchers who analyzed federal data on airline performance also said in a report being released Monday that consumer complaints to the Department of Transportation surged by one-fifth last year even though other measures such as on-time arrivals and mishandled baggage show airlines are doing a better job.

NPR: Airline Passenger Complaints Surged In 2012

There were one-time charges and gains, "repositioning" costs, impairment adjustments and ever-confusing special accounting measures.

WSJ: A Rally Built Atop Surprises, Mostly Bad