A news article in the Sydney Morning Herald this morning reported that at about 10:50 p.m. (1:50 p.m. GMT) on Sept. 6, an All Nippon Airways (ANA) co-pilot mistakenly hit a wrong button, causing his Boeing 737-700 aircraft to dive 1900 meters in 30 seconds.
The Morning Herald article stated that:
"The manoeuvre happened when the co-pilot, in trying to unlock the cockpit door for the captain who was returning from the toilet, mistook a command button for the cockpit door lock switch nearby."
The flight took off from Naha, on Okinawa island, en route to Tokyo's Haneda airport, where it landed safely. Two crew members were said to be slightly injured, and four passengers reported they were injured.
"The crux of the co-pilot’s error is believed to be due to the close proximity of the cockpit door button and the rudder trim knob, which he pressed by mistake resulting in the plane’s plunge."
The aircraft, which was at a height of 41 000 feet (12 500 m) at the time, at one point was tilted 131.5 degrees to the left and had a 35-degree downward tilt of its nose during its dive.
ANA apologized for the incident, which Japanese authorities are now investigating.
A Singapore news report on the incident with accompanying animation can be found here (the report says the plane dropped 19 000 meters, which is obviously wrong).