The Japanese Navy learned some lessons from Midway. Aircraft were refueled and re-armed on the flight deck, rather than in the hangars. All unused fuel lines were drained. The new carriers being built with only two flight deck elevators and new firefighting equipment. More carrier crew members were trained in damage-control and firefighting techniques. The losses later in the war of , ', and ' showed that there were still problems in this area. Replacement pilots went through a short training program, meeting the short-term needs of the fleet. This led to a decline in the quality of training. These inexperienced pilots were sent into front-line units, while the veterans who remained after Midway and the Solomons campaign were kept flying continually. As a result, Japanese naval air groups declined in quality during the war.