Post-Flashover Fire Investigations 

Fire investigators are regularly called upon to interpret burn patterns and to determine where fires originate. Origin and cause investigators often easily decipher pre-flashover fire patterns. The severe burn damage found in fully involved fires however, can be far more daunting to interpret, making origin determination extremely difficult.

In 2005, now-retired ATF Senior Special Agent and Certified Fire Investigator Steve Carman designed and helped present a seminar on Fire Dynamics.   As part of the class, two, identical, one-room burn cells with standard-sized doorways were each burned for seven minutes. Hours later, fifty-three experienced fire investigator-students (who had not observed the fires) were asked to briefly examine the cells and decide in which quadrant of each cell they thought the fires had started. 5.7% of the students correctly identified the quadrant of origin in each cell. A review was undertaken of investigators’ responses in similar, post-flashover exercises at the Federal Law Enforcement Training Center in Georgia. Though written records of those responses are not kept, anecdotal reports by long-time instructors indicate that since the class’ inception in the early-1990s, about 8-10% of students correctly identified the fire’s origin. Those who identified an incorrect origin typically reported were misled during their analyses by extensive, post-flashover-generated burn patterns.

Carman and others conducted additional testing into the fire behavior of and burn pattern generation in post-flashover fires at the ATF Fire Research Laboratory in July 2008.  The results of each of these tests, which were the basis for a CFITrainer module on “Post-flashover Fire”, have been collected and will be discussed.  This information on the nuances of fire science associated with fully involved, post-flashover burning will identify some of the common difficulties facing fire investigators in interpreting the burn patterns generated in such fires.

About Your Instructor

Steve Carman (ATF Senior Special Agent, retired) is the owner of Carman & Associates Fire Investigation based in Dunsmuir, California.  He served as a Special Agent with ATF from 1988 to 2008 assigned to the Sacramento and Redding, California offices.  He was certified as an ATF Certified Fire Investigator in 1993 and spent more than nine years as a member of the ATF's Western National Response Team.  Steve  graduated from the U.S. Coast Guard Academy in 1980 with a B.S. degree with High Honors in Physical Sciences.  Prior to joining ATF, he served six years as a Coast Guard officer including two as Commanding Officer afloat.  After that he spent two years in the private sector working in chemical and mechanical engineering.

Steve has investigated several hundred large-loss fires with more than 70 fire deaths and average fire losses of more than $1,000,000.  He has conducted and led numerous, complex arson and explosives investigations throughout the west resulting in many successful federal and state prosecutions.  He has lectured internationally on various aspects of fire science and investigation including fire dynamics, fire chemistry and fire modeling.  Because of his familiarity and work with fire chemistry and physics, Steve has focused much of his work and research towards the study of “unusual” fire behavior and its recognition during investigations.   Among his works was the publishing of an ATF monograph in October 1994 detailing his conclusions regarding a nationally puzzling fire phenomenon dubbed “High Temperature Accelerants.  His most recent work has revolved around efforts to educate the fire investigation community about post-flashover fire behavior.  He is a member of the Board of Directors of the International Association of Arson Investigators.  He is also an adjunct instructor at Cogswell Polytechnic College in California.