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A controversial American hybrid plane/helicopter crashed last week during a
training exercise at an airfield near Tuscon, Arizona, killing all 19 people on
board. It is the third time in nine years that an MV-22 Osprey has crashed,
casting a shadow over the unorthodox technology. Its tilt-rotor design allows it
to take off and land like a helicopter. Once airborne, its engines tilt forward
to allow it to cruise like a plane. An investigation is now trying to find out
why the aircraft suddenly pitched forward and nosedived into the ground.