 Around ten minutes after take-off, as the crew prepared for the onboard meal service, David Mark Robinson, a passenger seated in Row 7, became agitated, stood up and began to make his way down the aisle.Producing two sharpened wooden stakes from his pocket, Robinson stabbed flight attendant Denise Hickson and flight purser Greg Khan in the head on his way to the cabin galley.Khan tackled Robinson to unbalance him, eventually succeeding despite repeated blows to the back of the head from Robinson's stakes.