INTRODUCTION: Development of fatigue by flight crews is often insidious; symptoms of pilot fatigue may not be recognized until a deviation, violation, or an incident has occurred. Self-assessment may be difficult, but may provide insight into events that occur with fatigued flight crews. The purpose of this study was to evaluate characteristics and outcomes from self-reported fatigue related incidents and situations. METHODS: Reports from the National Aeronautics and Space Administration's Aviation Safety Reporting System (ASRS) involving operations under FAR part 135 or part 121 submitted during 2009-2011 were searched using the word "fatigue" in the text or the synopsis. Only reports from flight crew members regarding flight crew fatigue were included. RESULTS: Three hundred and seven reports from ASRS were identified that involved flight crew fatigue. Reports mainly consisted of descriptions of 1) proactive calls to management, calling in fatigued, or a refusal of flights by crews, 2) an admission of fatigue after an assessment of mistakes or review of handling of challenging events, or 3) narratives describing flight conditions or policies that had potential to cause fatigue. The descriptions were analyzed for proactive (calling in fatigued or reporting fatigue-causing conditions) or reactive (fatigue was realized after an incident or situation occurred) responses to fatigue. Outcomes were categorized into 1) fatigue calls and reports with no further action and those with management interaction and 2) characterization of reactive situations, such as altitude deviation, missed communications, non-adherence to standard operating procedures or evasive actions required. DISCUSSION: Reports involving fatigue provide qualitative information on flight crew recognition and assessment of fatigue and a lack of awareness of potential consequences of fatigued flight. These reports suggest that 1) comprehensive support for feasible policies that address flight crew fatigue are needed and 2) education and awareness are still needed to prevent fatigued flight, as fatigue is often recognized retrospectively.