I agree with you that Delta generally can't control the market price of fuel, but DL itself admitted that its refinery may have reduced the crack spread in that region, which if true means that DL did bring down the price of NYC-PHL area jet fuel for all purchasers, not just Delta.

In very few industries does one big competitor invest more than $300 million in a conscious effort to drive down the cost of an important input when all of its competitors can benefit from the price reduction. But Delta has done just that. Talk about a free rider problem.

http://www.reuters.com/article/2013/...0E31ZX20130523

http://www.bloomberg.com/news/2013-1...arts-unit.html

http://www.reuters.com/article/2013/...0IC11W20131022