Although the estimated yearly rate of helicopter accidents has been decreasing over the past decade, it has now reached a plateau still well above that for commercial aviation and fixed-wing general aviation. Flight Data Monitoring has proven effective at improving safety in the commercial aviation domain and is now being considered for implementation in the field of helicopter operations. Flight Data Monitoring is a voluntary and proactive safety program in which the retrospective analysis of flight data records and the implementation of safety metrics allows the identification of precursors to safety-critical events and the monitoring of progress towards safer operations. For instance, loss of control in flight during "approach" to a heliport or an helipad has been identified by the International Helicopter Safety Team as one of the leading causes of helicopter accidents. In particular, unstable approaches account for about a fourth of the accidents when categorized by phases of flight. This paper first provides an overview of the main occurrence categories and of the main contributors to helicopter accidents as identified by various entities concerned about the safety of helicopter operations. The paper then focuses on the development of a procedure to identify approach phases from flight data records by looking at parameters such as altitude and angle of approach, and to classify those approaches into various levels of stability depending on the variations of the relevant parameters along the approach trajectory.
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