Last month, one of South Korea's new F-15K fighter-bombers crashed, on takeoff, during a night exercise. The aircraft went down off the coast, and the flight recorder ("black box") has not yet been recovered. So far, neither the manufacturer, Boeing, nor the South Korean air force, has any idea of what caused the aircraft to crash. The two pilots were lost, and it appears that the aircraft, while practicing low level flying, flew right into the water. This sort of thing has happened before, to both military and commercial aircraft, and usually as a result of pilot error. But without the black box, one can only speculate. In the meantime, South Korea has grounded the other three F-15Ks, and asked Boeing to delay delivery of the next two aircraft, for at least a month. The South Koreans have also made it clear that they will hold the manufacturer responsible if the fault turns out to be with the aircraft. The F-15K is basically an upgraded version of the F-15E, and costs about $100 million each. South Korea is buying 60 of them.