The MV-22 Osprey accident last month in Okinawa rekindled concerns about the tilt-rotor aircraft, which was once known as the "widow maker" for those killed during its development.

Starting this year, Japan will see more of the odd-looking hybrids in its skies than the 24 deployed by the U.S. Marine Corps in Okinawa, and residents are worried about potential accidents in densely populated areas and noise issues.

Here are some basic facts and about the Osprey and the lingering issues surrounding it: