Airbus A319 accident near Chillicothe, Missouri, May 9, 2011

The NTSB's narrative final · quoted from the NTSB record

No adverse weather was forecast for the route. The seatbelt sign was turned off at FL320. The airplane leveled off at a final cruise altitude of 37,000' and the ride was smooth up until the turbulence encounter. Both the captain's and first officer's weather radar was in use before and during the turbulence event, and there was no adverse weather along the route visible on radar. The flight crew received no weather updates from Air Traffic Control, no pilot reports (PIREPS), and there was no traffic along the same route in front of this flight. Evaluation of the winds using FDR data revealed that the aircraft sustained strong and adverse wind fluctuations on all three axes during the turbulence encounter, which included an upwards vertical wind gradient was about 80 knots in a 10 second timeframe. Recorded ground weather radar information revealed that the flight was probably passing over or through the extreme top of a rapidly developing area of convective weather at the time of the turbulence encounter. Although ground based radar reflectivity data indicated that the precipitation rate within this rapidly developing cell at the time was light to moderate, detection of the cell would likely have required active adjustment of the aircraft's weather radar system. However, the flight crew was not actively manipulating the aircraft radar at the time of the event given the lack of severe weather indications.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.