What happened
On August 8, 1997, an AOM-Minerve S.A. McDonnell Douglas DC 10-30, registration F-GNEM, was operating flight IW 314 from Pointe-à-Pitre to Paris Orly. While cruising at flight level 350 over the North Atlantic, the aircraft encountered a sudden and violent bout of turbulence at 00:42 UTC. Flight data recorder analysis indicated significant vertical load factor fluctuations, ranging from +1.96 g to -0.51 g.
During the event, the aircraft entered the head of a cumulonimbus cloud. The sudden movement caused passengers who were not restrained to be thrown from their seats, striking overhead bins and the cabin ceiling. The crew immediately attended to approximately 30 injured passengers. Following consultation with a medical professional on board, the pilot decided to continue the flight, eventually landing safely at Paris Orly at 05:18 UTC.
The investigation
The investigation focused on the meteorological conditions and the aircraft's encounter with convective activity. Investigators examined the flight meteorological dossier, which included a significant weather chart (TEMSI) but lacked recent satellite imagery. The investigation also reviewed the functionality of the onboard Bendix RDR-1F weather radar, which was found to be in good working order and properly tested by the crew prior to the event.
Furthermore, the investigation analyzed the cabin environment, noting that the meal service had concluded and a film was being screened. The physical state of the passengers was examined, revealing that many of those injured were not wearing seatbelts at the time of the turbulence.
Findings
- The primary cause of the accident was the entry of the aircraft into the head of a cumulonimbus cloud that had not been identified by the crew.
- The crew had no visual indication of the clouds due to the night conditions and the lack of lightning associated with these specific convective cells.
- The lack of recent satellite imagery in the flight dossier prevented the crew from anticipating the presence of the convective mass.
- Severe load factor variations were exacerbated by the pilot's reactions to the turbulence, which caused oscillations in the aircraft's pitch.
- A significant contributing factor to the number of injuries was that many passengers were not wearing seatbelts, as they had unfastened them for comfort during the cruise phase.