On 27 August 2018, an Airbus A320 level at FL 300 encountered unanticipated turbulence which caused one of the cabin crew to fall and sustain what was belatedly diagnosed as spinal fracture. The Investigation found that the aircraft had flown through the decaying wake vortex from an almost opposite direction Boeing 747-400F at FL310 which had been observed to cross what was subsequently found to be 13.8 nm ahead of the A320 prior to the latter crossing its track 1 minute 40 seconds later that coincided with a very brief period in which vertical acceleration varied between +0.19g and +1.39g.