The UK Civil Aviation Authority has recognised the need for protection against the runway overrun over and above the standard protection recommended by ICAO. Normal protection for the aircraft is provided in ICAO's Annex 14 by the strip at the end of a runway, and a recommendation for the installation of a Runway End Safety Area (RESA). In the UK, the CAA has stated that as part of their safety management system the aerodrome licensee should review the RESA distance requirement for their individual circumstances on an annual basis through a risk assessment. However, current industry knowledge of circumstantial factors in runway overruns is limited. Also, current models that are used to determine likely overrun wreckage locations and RESA dimensions take no account of the operational conditions surrounding the overruns or the aerodrome being assessed. This study has attempted to address these needs by highlighting common factors present in overrun occurrences through the compilation and analysis of a database of runway overruns, and through the construction of a model of wreckage location that takes account of the conditions at an individual aerodrome. A model of overrun probability has been constructed and the consequences of an overrun have been examined. One outcome of the study is an awareness that the industry is in an extremely poor state of knowledge of operational characteristics of non-accident flights, which if not addressed will be a major barrier to future advancement of aviation safety improvement and research.