ANA incident on 737-700

[goaroundthrust]

TOKYO (Kyodo) -- An All Nippon Airways Co. flight from Okinawa to Tokyo's Haneda airport on Tuesday night made a steep dive while flying over the Pacific Ocean off Shizuoka Prefecture, slightly injuring two cabin attendants, the airline said Wednesday.

The Boeing 737-700 with 117 people on board dived around 1,900 meters from an altitude of some 12,500 meters in a span of about 30 seconds while the male captain, 64, had gone to the toilet and only the co-pilot was left in the cockpit, according to ANA and the Land, Infrastructure, Transport and Tourism Ministry.

The 38-year-old male co-pilot mistakenly moved a switch to operate the rudder for changing the plane's direction when he actually intended to unlock the door to the cockpit to let the captain back in, ANA said. There was no information about turbulence in the area at the time.

The Japan Transport Safety Board, affiliated with the ministry, will dispatch three aircraft accident inspectors on Thursday to the Haneda office of Air Nippon Co. which operated the ANA flight, officials said.

Flight 140, which departed from Naha airport at about 9:10 p.m. Tuesday, tilted to the left and dived at around 10:50 p.m. when it was flying about 40 kilometers south of Hamamatsu, according to ANA and the ministry. While no passengers were hurt, one cabin attendant sprained her neck and another suffered scratches, they said.

The co-pilot recovered the plane's posture and the captain took control again. After the incident, the plane continued its flight and landed at Haneda airport at around 11:30 p.m., they said.

ANA apologized to passengers and others concerned for causing concern.

[Slappy the Squirrel]

I like how they specify the gender of the pilot and co-pilot.

[iflyforpie]

[bcflyer]

How long would you have to hold the rudder trim over for to cause a plane to lose over 6000 ft? I can understand initally turning the wrong switch if you weren't paying attention, but you would think after the aircraft started to yaw he would realize his error.....

[Lost in Saigon]

While he held the rudder trim, the aircraft continued straight and level. There was no Visible yaw. Because the autopilot kept the aircraft straight and level, there was almost nothing for the pilot to see, or to react to.

It would have been some point later, when the rudder trim was near the stop, that the autopilot suddenly disconnected with almost full rudder input. The aircraft yawed and rolled almost inverted. That is what caused the loss of control.

EDIT: "Visible" added above

[J31]

While he held the rudder trim, the aircraft continued straight and level. There was no yaw. Because the autopilot kept the aircraft straight and level, there was almost nothing for the pilot to see, or to react to.

It would have been some point later, when the rudder trim was near the stop, that the autopilot suddenly disconnected with almost full rudder input. The aircraft yawed and rolled almost inverted. That is what caused the loss of control.

The auto pilot does not control the rudder. So if he started trimming the rudder the aircraft would have stated to yaw till the auto pilot could no longer hold level/LNAV track and would disconnect. Without intervention the aircraft would depart level flight and enter a spiral dive.

I would say by holding the rudder trim it would take 7-10 seconds before the auto pilot disconnected. You would be about 7-10 units out of neutral and it would be a wild departure from level flight when the auto pilot let go.

[bcflyer]

Can some 737 rated people comment on this? I've flown several transport category jets and on all of them, in normal straight and level flight, as soon as you trimmed the rudder you would feel the resulting yaw. Is the 737 different? I find it odd that the rudder trim would be overpowered by the autopilot.

[J31]

Can some 737 rated people comment on this? I've flown several transport category jets and on all of them, in normal straight and level flight, as soon as you trimmed the rudder you would feel the resulting yaw. Is the 737 different? I find it odd that the rudder trim would be overpowered by the autopilot.

No the 737 is the same as any other aircraft, you can feel the yaw as soon as you trim the rudder. See above......the auto pilot only controls roll and pitch. It does not control the rudder.

[linecrew]

There is a link to some computer animation of what the aircraft did in the 4th paragraph of this news article:

http://blogs.wsj.com/japanrealtime/2011 ... side-down/

[Lost in Saigon]

There is a link to some computer animation of what the aircraft did in the 4th paragraph of this news article:

http://blogs.wsj.com/japanrealtime/2011 ... side-down/

ANA said a 38-year-old co-pilot likely hit the rudder trim controls by mistake instead of pushing the door unlock button to let the captain in after he stepped out of the cockpit to go to the restroom.

Investigators said the co-pilot was quite experienced, with more than 35,000 total hours of flight time.

35,000 hours in roughly 20 years? I don't think so.

[bcflyer]

My guess is a typo and it should have read 3500hrs which is considered very experienced for asian F/O's. I still find it hard to believe he didn't feel the AC start to yaw and roll. Watching the video posted in another thread it shows the plane rolling for at least 10-15 sec before it really starts to turn over.

[SAR_YQQ]

Boeing makes a good yaw dampener - which does move the rudder. If not you get dutch roll at high speed.