to replace one of the small tanks. The difference in size put approximately greater weight on one side of the aircraft, but the tanks were located close enough to the aircraft's center of gravity to avoid serious performance problems. Eighteen P-38s were assigned the mission. One flight of four was designated as the "killer" flight, while the remainder, which included two spares, would climb to to act as "top cover" for the expected reaction by Japanese fighters based at Kahili. A flight plan was prepared by the Command Operations Officer, Marine Major John Condon, but this was discarded by Mitchell, who thought the airspeeds and time estimates were not best for intercepting Yamamoto. With several of his pilots assisting, Mitchell calculated an intercept time of 09:35, based on the itinerary, to catch the bombers descending over Bougainville, 10 minutes before landing at Balalae. He worked back from that time and drew four precisely calculated legs, with a fifth leg curving in a search pattern in case Yamamoto was not seen at the chosen point. In addition to heading out over the Coral Sea, the 339th would "wave-hop" all the way to Bougainville at altitudes no greater than 50 feet (15 m), maintaining radio silence. Although the 339th Fighter Squadron officially carried out the mission, 10 of the 18 pilots were drawn from the other two squadrons of the 347th Group. The Commander AirSols, Rear Admiral Marc A. Mitscher, selected four pilots to be designated as the "killer" flight: Captain Thomas G. Lanphier Jr. Lieutenant Rex T. Barber Lieutenant Jim McLanahan (dropped out with flat tire) Lieutenant Joe Moore (dropped out with faulty fuel feed) The remaining pilots would act as reserves and provide air cover against any retaliatory attacks by local Japanese fighters: Major John Mitchell Lieutenant William Smith Lieutenant Gordon Whittiker Lieutenant Roger Ames Captain Louis Kittel Lieutenant Lawrence Graebner Lieutenant Doug Canning Lieutenant Delton Goerke Lieutenant Julius Jacobson Lieutenant Eldon Stratton Lieutenant Albert Long Lieutenant Everett Anglin Lieutenant Besby F. Holmes (replaced McLanahan) Lieutenant Raymond K. Hine (replaced Moore) A briefing included the designated cover story for the source of the intelligence stating it had come from Australian coastwatchers, who supposedly had spotted an important high-ranking officer boarding an aircraft at Rabaul. Several historians say that the pilots were not specifically briefed on the identity of their target, but Thomas Alexander Hughes wrote that Mitscher told the assembled