By RUSSELL GRANTHAM The Atlanta Journal-Constitution Just six months after arriving, JetBlue Airways is leaving Atlanta. The New York discount carrier will end its single daily flights to Long Beach and Oakland, Calif., on Dec. 4. JetBlue executives, who had already cut back Long Beach flights, cited the crossfire of the dogfight between Delta and AirTran in both markets. JetBlue said it will instead use the planes to launch service between Boston and Long Beach, a Los Angeles suburb, and to add flights from New York to Oakland. In early September, JetBlue cut back from three daily flights to only one late-night "redeye" flight between Atlanta and Long Beach, a Los Angeles suburb. The carrier initiated a single redeye flight from Atlanta to Oakland at the same time. JetBlue CEO David Neeleman said it made more sense to use the aircraft elsewhere than to stay in a fight with Delta Air Lines and AirTran Airways. The latter added service to Los Angeles and San Francisco shortly after JetBlue. Although it never had a large presence, JetBlue's arrival was noteworthy because it brought cut-rate air service between Atlanta and the West Coast. Delta, which had long enjoyed a near monopoly on nonstop West Coast service, responded by cutting fares, adding flights and offering frequent flier bonuses. AirTran's addition of flights assures competition will continue.