What happened
On January 23, 2021, a SriLankan Airlines Airbus Industries A330-300, registration 4R-ALP, was prepared for a cargo flight from Bandaranaike International Airport to Changi International Airport. After the flight crew and cabin supervisor had completed their initial checks, the L1 door was closed and armed at approximately 11:13 hrs local time.
Shortly after the door was armed, a junior aircraft mechanic, who had remained on board to perform minor repairs in the business class cabin, was prompted by a ground official to disembark. Unaware that the door had been armed, the mechanic opened the L1 door, causing the emergency slide pack to deploy and fall onto the passenger steps. The incident caused a 41-minute departure delay, though the aircraft eventually departed under the provisions of the Minimum Equipment List (MEL) without any damage to the airframe.
The investigation
The investigation examined the sequence of safety and security checks performed by the cabin supervisor, the pre-departure activities of the engineering staff, and the oversight provided by the duty security officer.
Investigators looked into why the mechanic was unaware of the door's status and why the cabin supervisor's announcement to disembark ground personnel was not clearly heard in the flight deck. The inquiry also reviewed the security logs, finding that the duty security officer had failed to record the mechanic's departure time due to being assigned to other simultaneous duties. Furthermore, the investigation scrutinized the compliance of the cabin supervisor's safety and security checklists and the accuracy of the subsequent incident reporting.
Findings
- The primary cause of the incident was the failure to follow standard operating procedures regarding door arming and opening.
- The cabin supervisor did not physically verify the entire cabin area before arming the door and failed to ensure all ground personnel had exited.
- The junior aircraft mechanic did not check the armed/disarmed status of the door before attempting to open it.
- A lack of situational awareness contributed to the event, as the mechanic was unaware the door was armed, and the cabin supervisor was unaware the mechanic was still on board.
- The duty security officer failed to maintain an accurate log of personnel entering and exiting the aircraft because they were distracted by other assigned tasks.
- The cabin supervisor's post-incident documentation and voyage reports were found to be incomplete and non-compliant with established safety manuals.