IATA said European markets saw a more than 22 percent year-over-year decline in premium class use in January, while first and business class traffic on the North Atlantic slid by more than 14 percent.

"There is evidence that business passengers are trading down to cheaper tickets," IATA noted. "Economy travel has been falling at a slower rate than premium travel, and in fact has appeared to improve a little in the past two months."

IATA's analysis jibes with policies increasingly conveyed by corporations seeking to limit travel expenses, in many cases by shifting travelers from business class to coach, according to buyers and travel management company data.

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