An incident in which an All Nippon Airways aircraft briefly flew virtually upside down after a co-pilot mistakenly turned a key steering mechanism has sent shock waves through the aviation industry
TOKYO — An incident in which an All Nippon Airways (ANA) aircraft briefly flew virtually upside down after a co-pilot mistakenly turned a key steering mechanism has sent shock waves through the aviation industry.
Japan’s Transport Safety Board said Wednesday that ANA Flight 140, a Boeing 737-700 operated by ANA’s group company, Air Nippon, was on the verge of stalling after nose-diving more than 6,000 feet in 30 seconds Sept. 6. The aircraft, carrying 117 passengers and crew members, was en route to Haneda Airport after leaving Naha Airport on Okinawa.
The revelation came just hours after the first of the new-generation Boeing 787 Dreamliner jets on which the airline company has built its future strategy landed in Tokyo.
According to the safety board, an analysis of the aircraft’s digital flight recorder indicated the co-pilot, alone in the cockpit while the captain used a restroom, mistakenly turned the rudder trim knob twice to the left for a total of 10 seconds.
The co-pilot apparently mistook the knob for the cockpit door-lock switch as he tried to let the captain back in. The mistake is believed to have caused the airplane to tilt leftward and descend rapidly.
According to ANA, its aircraft usually tilt no more than 30 degrees when they roll, with the craft’s nose pointing up no more than 20 degrees and pointing down no more than 10 degrees. On Sept. 6, however, the aircraft rolled left and briefly reached a tilt of 131.7 degrees. Its nose pointed down 35 degrees at one point, the safety board also said.
“The figures are unbelievable, even in a case that requires such an urgent maneuver to avert a risk,” a source close to ANA said.
The airline also revealed Wednesday that a stick shaker, a mechanical device to warn pilots of an aircraft’s imminent stall, was activated during the incident.
On Sept. 7, ANA discovered after analyzing flight data that the airplane had been at risk of stalling and had flown virtually upside down. However, the company failed to make it public.
Two flight attendants were slightly injured, and six passengers became airsick or reported neck pains.