What happened
On November 21, 2004, an Air Nippon Network Co., Ltd. flight, operating as All Nippon Airways Flight 1617, was completing a scheduled service from Osaka International Airport to Kochi Airport. The aircraft, a Bombardier DHC-8-402 with registration JA841A, carried 15 passengers and 4 crewmembers.
During the landing on Runway 32, the aircraft encountered a crosswind. While the initial touchdown of the main wheels was successful, the aircraft's heading began to drift significantly to the right. The pilot attempted to correct the deviation using rudder input and reverse thrust, but the drift continued. As the aircraft slowed, the nose wheels momentarily lifted and then re-impacted the runway, at which point a master caution light illuminated. Despite efforts to maintain the centerline, the right main wheels exited the paved surface and entered the grass area. The aircraft eventually came to a stop at a heading of approximately 324 degrees, necessitating a tow back to the parking area.
The investigation
The investigation examined flight data from the digital flight data recorder (DFDR) and cockpit voice recorder (CV and CVR), as well as interviews with the crew and analysis of the aircraft's steering system. Investigators focused on the sequence of events during the landing roll, the functionality of the nose wheel steering at various speeds, and the crew's response to the steering light illumination and the aircraft's directional drift.
Findings
- The primary cause of the excursion was the inoperative nose wheel steering during the landing roll.
- The pilot attempted to use the steering control handle to correct the rightward drift, but the handle moved freely without providing any directional response.
- The crew was unaware of a manufacturer's advisory (All Operator Message No. 016) which provided guidance on handling steering issues.
- The airline had experienced previous instances of steering malfunctions but had not implemented specific measures to investigate the underlying causes or update training procedures accordingly.