What happened
On March 22, 2015, at 21:49 local time, an ATR72-212A, registration EC-KGJ, operated by Naysa, encountered severe turbulence while cruising at FL130. The flight was performing a scheduled commercial service between Tenerife Norte and Gran Canaria.
Prior to the event, the aircraft had climbed to FL130 to avoid cloud layers present at lower altitudes. After stabilizing at this level for approximately seven minutes, the aircraft was struck by convective turbulence that generated a vertical acceleration of 2.54 g. Because the "fasten seatbelt" sign had been deactivated, three individuals—two cabin crew members and one passenger—were standing in the cabin and sustained injuries. One passenger suffered a serious injury, while the two crew members and one other passenger sustained minor injuries. The flight crew immediately requested medical assistance and descended to avoid the turbulent area, landing safely at Gran Canaria airport.
The investigation
The CIAIAC investigation examined the meteorological conditions, the flight data, and the weather information provided to the crew. Investigators analyzed the aircraft's flight recorder (FDR) and cockpit voice recorder (CVR), noting that the aircraft had experienced icing during its initial climb, which had delayed the deactivation of the seatbelt sign.
The investigation also reviewed the meteorological maps used by the operator. While the London WAFC (World Area Forecast Centre) and AEMET (Spanish Meteorological Agency) had predicted turbulence and icing in the area, the specific significant weather maps provided to the crew by the operator did not indicate these hazards for the flight path. Furthermore, the investigation looked into the limitations of onboard weather radar in detecting certain convective phenomena.
Findings
- The primary cause of the accident was the occurrence of convective turbulence that could not have been foreseen by the crew.
- The operator utilized a significant weather map that failed to include the forecast for turbulence and icing in the accident location.
- A period of atmospheric stability during the three previous flights of the day, as well as the seven minutes of stable flight immediately preceding the event, contributed to the lack of anticipation of the turbulence.
- The inherent limitations of onboard weather radar in detecting certain types of atmospheric phenomena were a contributing factor.
Safety action
- REC 26/15: It is recommended that the operator, Naysa, utilize low-level significant weather maps issued by AEMET when generating flight dispatch information for low-altitude flights, such as those conducted between the islands.