Why Rivals Don't Copy Southwest's Hedging (Wall Street Journal, 28 May 2008)
With oil near $130 a barrel, why does Southwest Airlines stand alone in the airline industry in its aggressive use of hedging to keep fuel costs under control?
Southwest has locked in more than 70% of its jet-fuel requirements this year at a price equivalent to $51 a barrel for crude oil. By contrast, other big carriers have hedged 30% or less of their fuel needs this year. Those carriers generally expect to pay the equivalent of $85 to $100 per barrel of oil under their hedging programs.
There are some good attempts at an answer in the linked article.