U.S.-based Delta Airlines will soon become the world's first air carrier to produce its own jet fuel. Delta announced yesterday it is buying a oil refinery near Philadelphia from the Phillips 66 oil company for 150 million Dollars for the purpose. Delta chief Richard Anderson called buying a refinery an innovative approach to managing the airline's largest expense. Delta spent 12 billion dollar on jet fuel last year, which was about 36 percent of its operating expenses. Delta says making its own fuel will save it about 300 million dollar a year.