Helicopters play a vital role in the movement of people and cargo to and from the installations of the oil and gas industry at sea, often in challenging environments, such as nighttime, where accidents tend to have serious impacts. The ability to remain safe is largely reliant on the processes of hazard identification and risk analysis. However, the processes currently used do not provide the offshore helicopter industry with the desired levels of safety in nighttime operations. The reasons for this include serious methodological weaknesses in current processes, especially the lack of a holistic view of the safety-critical components of the industry; biased and over-simplistic analysis of accidents; overreliance on reported incidents of doubtful statistical utility; ad hoc survey methods to elicit opinions of pilots rather than facts about hazards; and the complete absence of predictive analysis using hazard data. This thesis addresses these weaknesses by developing and implementing a new and comprehensive methodology consisting of a number of processes used in an integrated manner, with novel contributions in taxonomy development, data quality and qualitative and quantitative data analytics to enhance hazard identification and risk analysis of nighttime offshore helicopter operations. The thesis demonstrates that this new methodology is effective in describing the safety-critical components of the offshore helicopter industry, identifying systematic hazards patterns and trends from the statistical analysis of accident reports, establishing the appropriate use of incident reports for hazard identification and risk analysis and exploiting knowledge and facts elicited directly from surveys of pilots to discriminate accurately the riskiest phases of flight, identify an exhaustive and statistically representative range of hazards related to the riskiest of such phases and analyse the hazard data through quantitative predictive analysis. The methodology is easily transferable to other operations in the helicopter domain by institutions of international reach (e.g., the International Civil Aviation Organisation, ICAO) and individual helicopter operators.