Date: 4th December 2024
Location: Copenhagen Airport, Denmark
Aircraft: Boeing 737-800, registration SE-RPU
Operator: Norwegian Air Sweden AOC
Flight Number: D8-3691
Route: Las Palmas, Canary Islands (Spain) to Copenhagen (Denmark)
Occupants: Unknown
Injuries: None reported
Summary of Events
On 4th December 2024, Norwegian Air Sweden flight D8-3691, a Boeing 737-800 en route from Las Palmas to Copenhagen, encountered a flaps asymmetry issue during its approach to runway 04L at Copenhagen Airport. The crew executed a go-around at approximately 750 feet MSL, climbed to 3000 feet, and entered a holding pattern. The aircraft subsequently landed safely on runway 04R at a higher-than-normal approach speed about 35 minutes after the go-around.
Passengers were informed by the captain that the issue occurred when flaps 30 were selected, causing an asymmetry in flap deployment. The captain addressed passenger questions at the gate upon arrival in Copenhagen.
Aircraft Information
The Boeing 737-800 is a twin-engine narrow-body airliner designed for short- to medium-haul operations. It features hydraulically actuated leading-edge slats and trailing-edge flaps to enhance lift during takeoff and landing. The flaps asymmetry protection system is designed to detect and manage discrepancies between the positions of the left and right flaps.
Sequence of Events
1. Approach Phase:
• During final approach to runway 04L at Copenhagen, the crew selected flaps 30.
• A flaps asymmetry condition was detected, triggering an alert.
2. Go-Around:
• The crew initiated a go-around at 750 feet MSL to ensure a safe landing configuration could be achieved.
3. Holding Pattern:
• The aircraft climbed to 3000 feet and entered a holding pattern to assess the situation and troubleshoot the flaps issue.
4. Landing:
• The crew opted for a lower flap setting to mitigate the asymmetry issue and landed on runway 04R at a higher-than-normal approach speed.
5. Post-Flight Communication:
• The captain explained the flaps asymmetry issue to passengers and answered questions at the gate.
Initial Findings
Flaps Asymmetry
• Flaps asymmetry occurs when there is a significant difference between the left and right flap positions, which can affect lift, drag, and aircraft controllability.
Crew Decision-Making
• The crew’s decision to execute a go-around and assess the situation in a holding pattern demonstrates adherence to standard operating procedures for managing abnormal configurations.
Safety Risks
1. Asymmetry-Induced Control Issues:
• Flaps asymmetry can result in roll and yaw imbalances, requiring prompt corrective action by the crew.
2. Higher Approach Speed Risks:
• A landing at higher speeds necessitates greater runway length and increased braking effort, raising the potential for overrun or tyre overheating.
3. Passenger Impact:
• Unexpected go-arounds and prolonged holding patterns can cause passenger anxiety and operational delays.
Recommendations
1. System Inspection and Maintenance:
• Conduct a detailed inspection of the flap actuators, position sensors, and asymmetry detection system to identify and rectify the root cause of the malfunction.
2. Crew Training:
• Reinforce training for handling flaps asymmetry scenarios, with emphasis on decision-making during approach and go-around procedures.
3. Passenger Communication:
• Enhance protocols for passenger communication during abnormal events to alleviate concerns and provide clear explanations.
4. Operational Reviews:
• Review fleet-wide maintenance logs to determine if similar flaps asymmetry issues have occurred on other aircraft.
Safety Lessons
This incident underscores the importance of robust flap asymmetry detection systems and the need for clear crew communication during unexpected events. The quick decision-making and adherence to procedures ensured a safe outcome.
Disclaimer
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Our investigation reports are based on all the evidence and facts available at the time of writing and posting. We apologise if any details are missed or are not fully accurate.
