What happened
On November 3, 2011, a Boeing 777-300ER was on final approach to runway 08R at Munich Airport. The flight, arriving from Manchester, was performing an automated landing under CAT I conditions. As the aircraft reached approximately 50 feet above the runway during the flare, it began to bank to the left.
Upon touchdown, approximately 420 meters beyond the threshold, the aircraft's Auto Flight System transitioned into rollout mode. However, the aircraft continued to drift toward the left edge of the runway. At approximately 944 meters from the threshold, the aircraft exited the runway via taxiway B4, traveling across the grass for about 400 meters. During this excursion, the crew applied rudder inputs, which caused the autopilot to disconnect and the aircraft to swing sharply 40 degrees to the right. The aircraft eventually crossed the runway at a 45-degree angle and came to a stop in the grass on the opposite side of the runway. There were no injuries among the 147 passengers and 15 crew members, though minor damage to the airfield was reported.
The investigation
The BFU investigation focused on the technical cause of the lateral deviation and the crew's response. Investigators examined the localizer (LOC) signal stability and the positioning of the LOC antenna, which had been relocated 1,000 meters behind the threshold of runway 26L. The investigation also reviewed the flight data, cockpit voice recordings, and the operational procedures of both the airline and air traffic control.
Findings
- The primary cause of the deviation was interference with the localizer signal caused by a BAE 146-RJ85 that was departing from taxiway B4. Because the BAE 146-RJ85 was at a low altitude and positioned between the incoming 777 and the antenna, it disrupted the signal, causing the autopilot to follow the distorted path.
- The crew decided to perform an automated landing without ensuring that the ground-based requirements for a safe automated approach were fully met.
- The crew did not notify air traffic control of their intention to perform an automated landing.
- The pilot in command attempted to initiate a go-around by pressing the TO/GA buttons, but the attempt failed because the go-around mode had already been deactivated by the initial touchdown of the left main landing gear.
- The pilots were unable to maintain the centerline because the autopilot remained engaged after touchdown, following the corrupted signal.
Safety action
Following the incident, the operator implemented several safety improvements, including:
- New guidelines for flight crews regarding successful go-around procedures after touchdown.
- Enhanced simulator training focused on managing go-around procedures once the aircraft has transitioned into ground mode.
- Specialized simulator training to practice managing localizer deviations during the flare phase at altitudes below 50 feet.