An improperly adjusted safety switch that rendered the aircraft’s pressurization system inoperative, an incorrectly wired cabin altitude warning switch that disabled a warning light and the pilot’s ineffective systems monitoring while distracted by an autopilot problem early in the flight were among the factors that led to a dangerous encounter with hypoxia, according to the Australian Transport Safety Bureau (ATSB). According to the safety report there is a continuing concern about hypoxia incidents especially in single- pilot, turbine-powered, pressurized aircraft.

 

** Verge of Consciusness / Aerosafety World /Nov 2011
      Mark  Lacagnina
** AeroSafety World Whole Issue November 2011