By Simon Hradecky, created Wednesday, Jul 6th 2011 13:36Z, last updated Wednesday, Jul 6th 2011 13:36Z A TuiFly Boeing 737-800, registration D-AHFH performing flight X3-2218 from Stuttgart to Tenerife Sur Reina Sofia,CI , was enroute at FL370 about 170nm northeast of Lisbon when both flight crew began to feel unwell .