Photo/Illutration A UH-60JA helicopter, the same type as the one that went missing off Miyakojima island in Okinawa Prefecture on April 6 (Captured from the Ground Self-Defense Force website)

Sources at the Defense Ministry downplayed internet speculation that a Ground Self-Defense Force helicopter that went missing near Miyakojima island in Okinawa Prefecture was downed by external forces.

Rumors are abounding that the helicopter, which was carrying 10 SDF crew members and SDF officials, fell prey to either a Chinese missile or radio waves. 

But the Defense Ministry quickly put out word soon after the helicopter went missing on April 6 that it had been involved in an "accident."

The Asahi Shimbun interviewed sources at the Defense Ministry to ask them how they made that determination.

On the rumor that the helicopter was attacked by an outside force, a senior official at the ministry said, “How can someone think like that?”

The officer believes that the theory spread partly because a lawmaker asked a question at the Diet on April 7 about Chinese forces’ involvement in the crash.

The UH-60JA helicopter took off from the Air Self-Defense Force base on the island at around 3:46 p.m. on April 6. It disappeared from radar screens at 3:56 p.m. that day.

The last contact the crew made was a wireless message transmitted at around 3:54 p.m.

The GSDF chief of staff announced on the evening of April 6 that the crash was an “aviation accident,” on the grounds that what are believed to be parts of the chopper were found off the coast of the island.

After the announcement, many netizens posted online messages that they believed the helicopter crashed after being attacked by Chinese forces.

Because the Chinese aircraft carrier Shandong was spotted in the sea south of Okinawa Prefecture for the first time on April 5, some people suggested it could be involved in the crash.

While some speculated on the internet that the helicopter was attacked by direct methods such as a missile, others suggested indirect means, including being subjected to radio waves to make the aircraft malfunction.

According to a senior official at the Defense Ministry who is an expert on helicopter operations, if a chopper is hit by a missile, a thundering noise will be heard and the body of the aircraft will be shredded into pieces.

However, for the latest crash, no local people have reported hearing a loud explosion.

In addition, no debris from the helicopter, which would have been floating on the surface of the sea if it had been downed by a missile, has been found.

Everything that has been found are believed to be outer parts of the helicopter that are easier to come off in an accident. 

In addition, officials haven’t established that any aircraft of unknown nationality approached Japanese airspace at the time of the crash, including fighters capable of firing a missile or a drone that can target a helicopter.

If a missile had been launched from an overseas site, it would have been detected by radar. However, no flying object was detected.

For those reasons, officials concluded that there is no possibility that the helicopter was downed by a missile, according to the senior Defense Ministry official.

The Asahi Shimbun also asked the same official about the possibility that the helicopter was subjected to mysterious radio waves that could make it nonoperational.

The senior official said that even if radio waves targeted an aircraft, they would impact larger surrounding areas, which means some abnormality would occur such as radar screens at an airport control tower detecting noise, or the control tower losing its ability to contact aircraft.

However, no such abnormality had been reported at the time of the crash.

In addition, no impact on communication devices or other devices used by private companies or individuals has been reported.

Also, emitting obstructive radio waves from the ground would have been difficult.

Therefore, officials concluded that there is also no possibility that radio waves caused the crash.

Another source at the Defense Ministry who is knowledgeable about how the crash occurred believes that it is likely that the gears that rotated the rotor blades of the helicopter were defective.

That made the helicopter quickly lose its propulsion and fall to the sea, the official said.

Because only one of the four rotor blades and what is believed to be an outer panel in the front portion of the helicopter have been found, the official believes that the aircraft “fell to the sea diagonally from its front portion. One of the rotor blades severely struck the sea surface, causing significant shock to the front portion of the helicopter.”

The official said that most of the body of the helicopter sank into the sea with the other three rotor blades still attached to it.

The official thinks the copter crashed because it malfunctioned due to the aircraft’s faults or age, or flawed maintenance.