What happened
On 8 July 2004, a Boeing 737-800, registration EI-DAR, operated by Ryanair, was performing a scheduled international flight from Girona to Paris Beauvoys. During the climb phase, the flight crew was navigating around weather cells. While following an ATC instruction to fly direct to the KANIG waypoint, the aircraft encountered a rapidly expanding towering cumulus cloud.
At approximately 17:18 UTC, while at flight level 170, the aircraft entered the top of the cloud and encountered severe turbulence lasting roughly 10 seconds. The aircraft experienced significant vertical accelerations, ranging from +2.096 g to –0.255 g. During this period, the cabin crew, who had been released for in-flight service, were violently tossed about the cabin. One flight attendant struck the cabin ceiling and door handle, sustaining serious injuries, including two fractured ankles. Another flight attendant suffered various contusions.
Upon learning of the serious injury, the pilot in command decided to abort the flight to Paris and return to Girona. The aircraft landed safely at Girona Airport at 17:52 UTC, where medical assistance was waiting.
The investigation
The CIAIAC examined the flight data recorder (DFDR) transcripts, which confirmed the extreme vertical accelerations and airspeed fluctuations during the encounter. The investigation also reviewed meteorological data, which indicated significant wind shear and changing wind directions at various flight levels, a known precursor to turbulence.
Investigators also reviewed the operator's manual and the crew's use of the onboard weather radar. While the crew attempted to avoid the cloud, the investigation noted that the radar did not show significant echoes, and the crew's decision to release the cabin crew for service was scrutinized against the known weather conditions.