the wall of a building may happen in a matter of seconds. The  sequence  of  events  is  the  investigator’s  best estimate  of  what  could  have  happened. Reconstructing  the  Mishap Sometimes you will find that reconstructing the mishap will help you get a clear picture of how the mishap occurred. Using your best guess of the sequence of  events,  walk  through  the  mishap. Have those who take part in recreating the mishap proceed up to the point of the mishap. Use original players if they are not too upset to revisit the scene. Go through the events slowly; then stop and discuss the events. Be careful not to repeat the unsafe act. You don’t need to have another mishap on your hands! Beyond the point of the mishap, talk about the action taken and walk through it again. Try other possibilities to see if they could have been contributing causes. Videotape the reconstruction and view the tape. Many times you will discover   the   cause   of   the   mishap   through   the reconstruction. Checking Precedence During your investigations you should also check to see if this same type of mishap has happened before. Based on the precept that there are “no new causes,” a previous mishap could provide clues to this mishap. The Naval  Safety  Center,  systems  commands,  and  type commanders have information on previous mishaps, near-mishaps,  and  systems/equipment  problems  that may  provide  insight.  Reviewing  this  type  of  information also aids in formulating corrective actions. Determining  Criminal  Evidence A mishap is an unplanned event. A criminal act is an intentional or planned event. A deliberate act is not a mishap. The criminal act may not be readily obvious until the mishap investigation is started. Arson, for example,  may  not  be  determined  until  most  of  the mishap investigation is completed. When doing an investigation, if you find criminal evidence, stop the investigation and inform your chain of command. A mishap investigation board that finds a possible criminal act will stop its investigation, and the senior  member  will  inform  the  chain  of  command. Nonprivileged  physical  evidence  can  be  turned  over  to criminal investigators. The sources of the evidence and privileged information are never revealed or turned over. If directed, a mishap investigation may continue, depending on the mishap. For example, if an arson fire occurred, but investigators found several hydrants out of commission and several hoses missing, a mishap investigation might look into those problems. Analyzing Mishaps A  variety  of  analytical  techniques  are  used  in mishap  investigations.  Some  are  simple,  while  others derived  from  civilian  investigators  are  quite  sophisti- cated. In this section we will define and discuss a few of the more common analytical techniques used by DOD personnel. An analysis of a mishap involves many methods and techniques of arranging facts. The facts can be used for the  following  purposes:    To help determine what additional information is needed   To establish consistency, validity, and logic   To establish sufficient and necessary causes To  help  guide  and  support  judgments  and opinions Some methods of analysis are used both to prevent mishaps  and  investigate  them.  Systems  safety  and failure mode analysis are detailed methods used when investigating  systems  involving  complex,  interrelated components.  The  Navy  may  use  these  methods  for aircraft  and  weapons  systems  investigations.  Some  of the results of these analyses can also be used to predict mishaps  or  the  possibilities  that  certain  mishaps  will occur. The following techniques are used by some Navy mishap investigators, depending on their training and the extent of the investigation. Training is available in the techniques through the Naval Safety School and local colleges and universities. FAULT  TREE  ANALYSIS.—  The  Navy  uses fault tree analysis to determine if a particular system, component, or   equipment   requires   planned maintenance.  It  asks  questions  such  as,  If  maintenance is not done, will the system fail? If the system fails, what is  the  result?  Will  personnel  get  injured?  Will operational  readiness  be  damaged?  The  fault  tree  is  a 4-15