In a recent incident, the 20mm cannon on a Japanese F-4EJ Phantom began firing without the trigger being depressed. While there were no casualties (a bus and medical facility were hit), the Japanese suspended loading these cannon in all of their aircraft and stopped flying F-4EJs briefly. It was finally determined that the problem was in the wiring circuits to the wing cannon, which are not mounted in Japanese F-4EJs. Circuits are provided to fire cannon mounted in pods, but the Japanese do not use them. It was cheaper, however, to leave the wiring in place and ignore it rather than remove it. The Japanese determined that the pilot did not pull the trigger, but that when the aircraft rolls to one side with the nose cannon armed, the unused wiring in the wings generates a false firing signal. The Japanese plan to physically cut these wires in all 184 of their F-4EJs and return them to duty.--Stephen V Cole