On 13 September 2017, the airspeed of a Boeing 737-800 unexpectedly increased during an intentionally high speed descent and the Captain’s overspeed prevention response, which followed his taking over control without following the applicable procedure, was inappropriate and led directly to cabin crew injuries, one of which was serious. The Investigation found that the speed increase had been the result of a sudden decrease in tailwind component associated with windshear and noted that despite moderate clear air turbulence being forecast for the area, this had not resulted in the seat belt signs being on or any consequent cabin crew briefing.