The investigation of the Swissair Flight 111 (SR 111) occurrence was complex and involved detailed examination of many operational and technical issues. The information in Part 1 of the report is organized into the subject areas specified by the International Civil Aviation Organization investigation report format. While the investigation uncovered many facts with respect to the flight, the aircraft, maintenance, personnel, and so on, only factual information that is pertinent to understanding the SR 111 occurrence is provided in this part along with some preliminary evaluation (first-stage analysis) that serves as a basis for the Analysis, Conclusions, and Safety Action parts of the report.