(FORTUNE Magazine) – Outraged at gas prices? Be happy you're not running an airline. With oil prices hovering in the mid-30s per barrel, the industry is feeling the pain. Every time oil prices rise by $1 per barrel it costs the airline business $500 million, but those costs aren't evenly distributed. Thanks to hedging (whereby airlines basically guess where prices are headed in the near future and negotiate fuel delivery at a given price), some carriers are far more protected against oil spikes than others. Strategies differ wildly--United and Northwest don't hedge at all, whereas Southwest is in the enviable position of having 80% of this year's fuel needs hedged at $24 per barrel. --Adam Edstrom