US airlines see benefit from financial reform law

* New law limits speculative commodities trading

* Airlines expect more predictable fuel prices over time

* Economists split on whether speculators drove prices up

By John Crawley

WASHINGTON, July 21 (Reuters) - U.S. airlines see a multi-billion-dollar benefit from the financial reform legislation signed into law on Wednesday, predicting it will cut their fuel costs as it curbs speculative commodities trading.

Every $1 increase in the price of a barrel of oil costs airlines $465 million per year in additional expenses, according to industry figures.

"The legislation has the potential to be a multi-billion-dollar benefit to this industry," James May, chief executive of the Air Transport Association, told Reuters.

A provision in the measure signed by President Barack Obama limits the size of trades, or futures contracts, for anyone not hedging with the intent of taking delivery of fuel.

Fuel consumers have argued that speculation in recent years caused volatile oil price swings and higher costs that drove some carriers under and severely tested the financial stability of others.