The Okinawa prefectural government is angry with the US military after it ignored a request to halt flights of the MV-22 Osprey transport aircraft following an accident during a training mission in Australia.

The US military also ignored a similar request from Japan's national government to ground the aircraft and operated Osprey flights over Japan on Monday.

In Saturday's accident, which took place during military exercises off the northeast coast of Australia, three US Marine Corps personnel are missing and presumed killed. An Australian Navy survey vessel located the sunken Osprey on Sunday night.

The accident is just the latest involving the Osprey, which is a state-of-the-art "heli-plane" transport aircraft that uses oversized tilted rotors on shortened wings to take off vertically before pivoting the wings in flight to enable flight like a conventional airplane. The accident has raised new concerns in the Japanese government and residents of Okinawa.

Angry on Okinawa

On Tuesday, Okinawa Vice Governor Moritake Tomikawa met with Lt. Gen. Lawrence Nicholson, the commander of all US forces in Okinawa prefecture, and requested that the Osprey aircraft be grounded.

Tomikawa told local media that Lt. Gen Nicholson dismissed the request on the grounds that "Ospreys are flying around the world," and it is "the military's policy."

In a statement issued to DW, Tomikawa said "we cannot contain our anger" over the US continuing flight operations.

"MV-22 Ospreys have caused fatal accidents at this stage of development in the past," an official at the Okinawa governor's Military Base Affairs Division told DW.

"We oppose the deployment of MV-22 Ospreys because the causes of the accidents have not been determined and that leads to growing anxiety among the people of Okinawa Prefecture," the official added. "Considering this, it is hard to dispel people's concern."

In Washington on Monday, Captain Jeff Davis, a spokesman for the Pentagon, told media that safety was "paramount for all of our operations," adding that the US was "talking with the government of Japan about safety."

That is unlikely to win over Okinawa residents, however, many of whom claim the aircraft has a poor safety record and poses a threat to their safety.

Not a 'death trap'

Opposition to flying Ospreys also mounted in December, when one of the aircraft ditched at sea off Camp Schwab in northeast Okinawa. The US was quick to rule out mechanical failure as a cause of the accident, which was subsequently put down to the aircraft's rotor blades striking a refueling line during in-flight refueling operations. There were no casualties in the incident.

The Osprey's unwanted reputation dates back to its development stages. In 1992, seven crew and passengers were killed in a test flight, while 23 Marines died in two accidents in 2000. The aircraft's poor reliability and steep maintenance requirements have been largely rectified, the military says. There has only been one documented accident involving an Osprey since it was first deployed in a combat zone, in Iraq in 2007. It later went on to serve in Afghanistan.

"Any local government would be concerned about a military aircraft crash, especially when an accident occurs near civilian districts," Garren Mulloy, an associate professor of international relations at Tokyo's Daito Bunka University, told DW.

"This aircraft is known to have problems - although it would be wrong to describe it as the 'death trap' that some are saying," he added.

"The issue is that this is a new type of aircraft and, as often happens with first generations of new aircraft, there are issues that need to be worked out in terms of training and operations. Quite frankly, the Osprey does not have a particularly high accident rate, although more people may have been killed in these aircraft because they are transport aircraft that carry passengers."

Mulloy also said that the latest disagreement over Osprey flights was another episode in a long-running dispute between the US and Okinawa over the US military bases on the Japanese island chain.

"Okinawa is in dispute with the US and the national government over the US military presence on Okinawa and they are using anything and everything at their disposal as a stick to beat them with, and the Osprey issue is just another stick," Mulloy said.

A versatile flying machine

The Osprey has a top speed of 530 kph (330 mph), almost double the speed of present transport helicopters, and a range of 3,900 kilometers (2,400 miles), five times the range of the aging CH-46 Sea Knight helicopter that it is replacing.

The aircraft can seat 32 troops and has an optimum cargo load of just over 9 tons, four times greater than the helicopters it is replacing in the US military. It is also capable of operating from aircraft carriers and can be refueled in flight.

Those attributes make it an appealing vehicle for the US military and 24 aircraft are presently stationed at the US Marine Corps' Futenma Air Station in Okinawa There are also plans to deploy more of the aircraft to Yokota Air Base, on the outskirts of Tokyo, starting in 2020.

The Japanese armed forces have also been impressed by the versatility and capability of the Osprey and Tokyo has purchased a number for assessments and training purposes. Japan is planning to purchase 17 of the aircraft in the coming five years.