What happened
On March 2, 2023, an Airbus A3/330-900 was operating a long-haul flight from Frankfurt, Germany, to Sir Seewoosagur Ramgoolam International Airport in Mauritius. While cruising at flight level 390 within the airspace of the Republic of Seychelles, the aircraft encountered high-intensity turbulence.
The sudden atmospheric disturbance caused significant movement within the cabin, leading to 6 passengers suffering serious injuries and 15 passengers, along with one cabin crew member, sustaining minor injuries. The aircraft itself sustained only minor damage.
The investigation
The BFU investigation focused on the meteorological conditions, the functionality of the aircraft's onboard systems, and the crew's response. Investigators examined the weather radar performance, specifically the IntuVue RDR-4000 system, and reviewed the flight crew's maneuvers. The investigation also looked into the airline's training protocols regarding weather phenomena and the use of onboard communication systems. Additionally, the BFU reviewed the airline's emergency response and passenger data management during the aftermath of the event.
Findings
The primary cause of the turbulence encounter was a cloud area that appeared green on the navigation display, indicating a region of up-and-down currents that was not visually identifiable as hazardous to the crew. The flight crew initiated a course change approximately 20 nautical miles before reaching the area, but this maneuver was too late, resulting in the aircraft entering the upper layer of the cloud mass.
Several contributing factors were identified:
- The weather radar was set to the 'ALL WX' mode, which did not display turbulence indicators on the navigation display.
- The rapid growth of the cloud formation meant the crew only recognized its true extent shortly before impact.
- Some passengers were not wearing seatbelts at the time of the encounter.
- Deficiencies were noted in the airline's initial safety and emergency procedures training, particularly regarding the use of the aircraft's internal communication systems.
Safety action
Following the investigation, the airline implemented several measures to enhance safety, including:
- Implementing Flight Crew Notices (FCN) to increase awareness of the IntuVue RDR-4000 weather radar's behavior.
- Providing additional training and instructional videos regarding weather radar usage.
- Updating training materials to include more detailed information on long-haul weather phenomena, such as the Intertropical Convergence Zone (ITCZ).
- Establishing a 'Flight Watch Pilot' role within the Operations Control Center to monitor flights and provide real-time weather advice via ACARS.
- Enhancing training for the correct use of the service interphone during emergency procedures.