The U.S. military in Okinawa has resumed flying the type of transport helicopter that just last week dropped a large metal part onto a school playground in Ginowan. The U.S. military has explained — and the Japanese government has accepted — that the accident was due to human error by the chopper’s crew and not linked to any mechanical problem with the aircraft. But given that the mishap — involving an elementary school — could have had grave consequences, a fundamental solution should be considered to prevent such incidents from ever happening again.

On the morning of Dec. 13, a square-shaped metal window frame, measuring 90 cm by 90 cm and weighing 7.7 kg, fell from a CH-53E helicopter out of U.S. Marine Corps Air Station Futenma when it was flying over the Futenma No. 2 Elementary School. The frame landed in the playground where 54 children were taking part in physical education classes, with the nearest student about a dozen meters from where it hit. It was only good fortune that nobody was hurt. As Chief Cabinet Secretary Yoshihide Suga said, it was an accident that caused anxiety among Okinawa residents and should never have happened.

The window frame was on the right side of the pilot’s seat and is used for emergency escape. The Defense Ministry quoted the U.S. forces as explaining that the frame fell off because the crew failed to notice that the window lever had not been securely fastened with a wire and then the lever was accidentally shifted to the escape position. Although a U.S. Marine commander apologized to the Okinawa Prefectural Government and the school, the U.S. forces have fallen short of promising that aircraft from the Futenma base will no longer fly over local schools, saying only that they will try as much as possible to avoid such flight paths.

The incident occurred exactly a year after an Osprey tilt-rotor transport aircraft from the Futenma base crash-landed on the coast at Nago. Six days before the latest incident, a small cylindrical object was found on the roof of a nursery school in Ginowan. A camera installed by local authorities captured images of a CH-53 flying near the nursery school around that time. Although the U.S. military admits that the object was a part from a CH-53 helicopter, it denies that it fell from a flying aircraft, saying that its parts inventories are all at their proper quantities.

In 2004, a CH-53 from Futenma crashed onto the main building of Okinawa International University, located close to the base, causing a fire and rendering the building unusable for some time. Accidents involving U.S. military aircraft have continued since. In addition, since 2013 there have been at least six confirmed cases in which objects fell from U.S. military aircraft in Okinawa. Even a small object falling from an aircraft can cause serious injuries if it strikes people on the ground. The Japan-U.S. Status of Forces Agreement, which gives primary legal jurisdiction to the United States over accidents caused by the U.S. military during training, hampers investigations by the Japanese police into these accidents. The government should pursue revising the accord.

Both the Japanese and U.S. governments should be aware that members of the Okinawa Prefectural Assembly — from both the ruling and opposition camps — demonstrated strong animosity toward the U.S. military over the latest accident. Assemblies in at least 12 municipalities unanimously adopted resolutions to protest the incident. Gov. Takeshi Onaga noted that the anxiety of people in Okinawa has been heightened to an unprecedented level and even said the U.S. military “is no longer a good neighbor.”

The operation of CH-53E helicopters at the Futenma air base resumed Tuesday, just days after the Japanese government called on the U.S. to refrain from flying that type of aircraft. A fundamental solution should be pursued to prevent the recurrence of similar accidents, including shutting down the Futenma base, which is located in the middle of the city of Ginowan, and transferring its functions to other U.S. bases.

The national government is pushing the construction of a new U.S. military facility in the Henoko area of Nago in the northern part of the prefecture, to take over Futenma’s functions. The relocation of the Futenma base may at least reduce the risk from the U.S. military aircraft flying frequently over a congested residential area. However, Okinawa people’s sentiments against the heavy concentration of the U.S. bases on their island, and the anger and anxieties over repeated crimes and accidents involving the U.S. military, remains deep-rooted. More thorough measures to prevent crimes and accidents must be implemented.