Incident Overview
On March 31, 2014, China Airlines flight CI 6416, a Boeing 747-400F cargo aircraft registered as B-18721, departed Abu Dhabi International Airport at approximately 13:04 local time for a cargo flight to Taoyuan International Airport. The flight crew consisted of one captain and two first officers. The approach and landing were conducted on runway 23R using an instrument landing system (ILS) approach.
Approach and Landing
During the descent, the crew discussed using flap 25 for landing due to heavy landing weight and requested a full-length runway exit from air traffic control. They decided to engage autoland unless visual conditions allowed manual landing. At about 4.1 nautical miles from the airport, the tower cleared another aircraft for takeoff on the same runway, then issued landing clearance to CI 6416 at approximately 0.7 nautical miles. The aircraft remained stable on the localizer and glideslope until 100 feet above ground, after which a right deviation began, reaching a maximum bank of 5.6 degrees. Touchdown occurred 2.5 degrees right of centerline, and two seconds later the right main landing gear exited the runway edge. The aircraft rolled approximately 1,400 feet before returning to the runway, damaging six runway edge lights and one taxiway edge light. The crew did not disengage the autopilot until after returning to the runway.
Post-Landing Actions
The crew reported no abnormalities during landing except for an unusual autopilot attitude. After taxiing to the cargo apron, they inspected the aircraft and found no damage, so they did not report the excursion. The following morning, Taoyuan Airport personnel discovered damaged edge lights and tire marks, which led to the identification of the aircraft involved.
Investigation Findings
The Aviation Safety Council (ASC) conducted the investigation with participation from the Civil Aeronautics Administration, the US National Transportation Safety Board, Taoyuan International Airport Corporation, and China Airlines. The investigation concluded with 10 findings and 5 safety recommendations.
Probable Cause
- The flight crew did not notify the tower of the intent to use autoland and did not ensure the ILS sensitive area was protected. A departing aircraft on the same runway crossed the ILS sensitive area, causing signal interference.
- The interference negatively affected the autopilot and navigation systems, causing the aircraft to deviate from the runway centerline during landing. The pilots did not actively control the aircraft or disengage the autopilot when unexpected deviations occurred, resulting in the runway excursion.
Other Findings
- All crew licenses and medical certificates were valid. No evidence of alcohol or drug impairment.
- The accident was unrelated to aircraft maintenance, airworthiness, or airport facilities.
- Taoyuan Airport's single-runway operations during high traffic periods increased controller workload.
- The airport did not re-identify hazards or conduct risk assessments when reducing daily inspection frequency.
- After the incident, China Airlines personnel did not detect the abnormality; the cockpit voice recorder data was lost due to maintenance activities with electrical power on.
Safety Recommendations
- To China Airlines: Enhance training on autoland procedures, standard callouts, and evidence-based training effectiveness.
- To the Civil Aeronautics Administration: Oversee China Airlines' implementation of recommendations.
- To Taoyuan International Airport Corporation: Strengthen foreign object debris detection and control, and implement change management per safety management system requirements.