(NewsNation) — A crew member died after a U.S. military Osprey aircraft carrying eight people crashed Wednesday off Japan’s southern coast during a training mission, according to Coast Guard officials.

What caused the crash was not immediately known, Coast Guard spokesperson Kazuo Ogawa said.

Operational since 2007 and in development since the 1980s, Ospreys have become controversial after a number of past accidents throughout the years, with some in the military even referring to it as the “widow-maker.”

An Osprey is a hybrid aircraft that takes off and lands like a helicopter. Once it takes flight, it can rotate its propellers forward and cruise faster, like an airplane. Versions of the Osprey are flown by the U.S. Marine Corps, Navy and Air Force.

Past crashes include one in December 2016, where a U.S. Marine Corps Osprey crashed off the Okinawa coast. Two of the five crew members in this incident were injured.

Most recently, a U.S. Marine Corps Osprey carrying 23 Marines crashed on a north Australian island in August, killing at least three people and critically injuring at least five during a training exercise.

This marked the fifth fatal Marine Osprey crash since 2012.

It’s not only the accidents that have some questioning the Osprey — according to The Conversation, its high cost and long development time have also given some pause.

The U.S. Government Accountability Office, in 2009, wrote that after 20 years of development, the Osprey demonstrated in Iraq that it could complete missions in low-threat environments, and its speed and range were enhancements. However, the GAO noted that challenges may limit its ability to accomplish “the full repertoire of missions of the legacy helicopters” it is meant to replace.

“Additionally, the suitability challenges that lower aircraft availability and affect operations and support costs need to be addressed,” the GAO report said.

The Quincy Institute for Responsible Statecraft wrote that the Department of Defense Inspector General in 2019 said the Osprey remains at risk of engine failure.

Air Force Special Operations Command ordered a temporary stand-down of its Osprey fleet last year after safety incidents where the Osprey clutch slipped, causing an uneven distribution of power to its rotors.

The Marine Corps and Navy have reported similar clutch slips. Each service has worked to address the issue in their aircraft; however, clutch failure was also cited in a 2022 fatal U.S. Marine Corps Osprey crash that killed five near Glamis, California.

Trial attorney Timothy A. Loranger, a pilot and U.S. Marine Corps veteran who spent years as an aircraft mechanic, represents widows trying to gather information in the aftermath of the 2022 Osprey crash. 

He said the Osprey had a bad reputation for years, even when he was in the military. 

“Every crash is devastating, and every crash is really hard for the families who’ve been involved in these kinds of disasters, and also the military people who are serving, because they have to get into an aircraft that they’re maybe not sure is in its safest condition,” he said. “These are really heartbreaking issues.”

Shutting down the Ospreys altogether could be detrimental to the Marine Corps and Air Force’s mission, Loranger said, but at the time, service members shouldn’t be asked to take unreasonable risks. 

“If the government or the manufacturers can do something to lessen that risk, then that needs to happen,” he said. “And that may include grounding the aircraft, spending the time and resources necessary to really examine the issues, figuring out what the problem is and then resolving it.”

Okinawa Gov. Denny Tamaki told reporters Wednesday he would ask the U.S. military to suspend all Osprey flights in Japan. Japan’s Prime Minister, Fumio Kishida, on the other hand, declined to say whether he would seek a temporary suspension of Osprey operations in Japan.

Loranger noted Marine data shows that Ospreys have flown for hundreds of thousands of hours without major mishaps, a good indication the aircraft is generally a safe platform. 

Bell Boeing, which manufactures the Osprey, said it has a fleet of more than 400 aircraft with a total of 600,000 flight hours.

The Osprey does fulfill an important role, Loranger said. 

“But there have been crashes and people have lost their lives,” he added. “We can’t ignore those facts. Everything has to be done to find out what caused those crashes so that they aren’t repeated.”

Budget documents show that none of the three military branches flying the Osprey have plans to buy additional airframes, Military.com reported earlier this year, which the publication says is a sign the Pentagon isn’t growing the fleet.

Liz Mildenstein, a spokeswoman for the office, said in an email to Military.com that the Ospreys are expected to serve “through the 2050s,” and the program office will continue to support the aircraft “for decades to come.”

The Associated Press contributed to this report.