USING A FORMAL LANGUAGE TO SUPPORT NATURAL-LANGUAGE IN ACCIDENT REPORTS

Accident reports written by official bodies, such as the Air Accident Investigation Branch of the United Kingdom's Department of Transport, are produced in response to all major civil aircraft accidents or inci dents. There are many statutory, legal and commercial implications tha t rest on the analysis, conclusions and recommendations that these rep orts contain. Air accident reports usually follow a standard format of synopsis followed by factual information, including history of flight and the systems involved, followed by analysis and conclusions. Final ly, there are safety recommendations aimed at preventing a recurrence of the accident. Natural language is the primary means of communicatin g all of these findings. In requirements engineering there is an incre asing recognition that natural language is not always an adequate mean s of expressing some of the detailed reasoning associated with the cau sal analysis of complex systems. Recent work in software engineering h as explored the use of formal, mathematically based, techniques to hel p to gain the required level of clarity and precision. It is argued th at accident reports, like requirements documents, could benefit by the use of formal techniques to complement the usual natural language des criptions. In this paper one specific accident report is considered. T he limitations of its natural language descriptions are examined and t he use of a Petri Net notation to help to elucidate its ambiguities is explored.