ANA Japan roll incident.
Courtesy of the Aviation Herald:
An All Nippon Airways Boeing 737-700, registration JA16AN performing flight NH-140 from Okinawa to Tokyo Haneda (Japan) with 117 people on board, was enroute at FL410 about 23nm south of Hamamatsu (Japan) when the aircraft violently rolled left causing injuries to two flight attendants and descended by about 6000 feet levelling off at FL350 again. The flight continued to Tokyo's Haneda Airport for a safe landing. The two injured flight attendants were delivered to a hospital with flesh wounds.
The airline reported, that the captain (64, 16,000 hours total experience) had taken a toilet break and was about to return to the cockpit requiring the first officer (38, 2400 hours total experience) to open the cockpit door. The switch to open the cockpit door is located about 10 centimeters/ 4 inches away from the rudder trim switch. By mistake the first officer operated the rudder trim switch instead of the door opening switch causing the aircraft to violently roll left and descend by about 6000 feet before the first officer was able to return the aircraft to stable level flight. The captain subsequently entered the cockpit. Two cabin crew received minor injuries (flesh wounds), no other injuries occurred. There was no turbulence in the area at the time of the occurrence.
Japan's Transportation Safety Board rated the occurrence a serious incident, opened an investigation and dispatched three investigators on site.