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Photo of corrugated stainless-steel tubing

ATF Investigation Report on Lessons Learned from 2 Line-of-Duty Deaths

Posted: Aug. 10, 2023

Updated: Sept. 21, 2023

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A report and companion video have been released following the investigation into the line-of-duty deaths (LODDs) of 2 firefighters with the Howard County (Maryland) Department of Fire and Rescue Services (HCDFRS).

The report and video include the results of an investigation conducted by the Baltimore Field Division of the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) and ATF’s Fire Research Laboratory showing a similar sequence of events that resulted in the deaths of Firefighter Nathan Flynn in 2018 and Captain Joshua Laird in 2021.

Lightning-induced corrugated stainless-steel tubing failure

The ATF’s investigation determined the origin and cause of both fires to be lightning-induced arc failure of corrugated stainless-steel tubing (CSST), a common gas supply piping used in residential construction.

The 2018 fire

The July 23, 2018, fire that resulted in the LODD of Firefighter Flynn occurred in an 8,400 square foot single-family residence. ATF personnel utilized field fire testing, large-scale laboratory fire testing, advanced computer fire modeling and electronic data sources to assist with determining the origin and cause of the fire, the route of fire spread throughout the structure, and the events that led to the firefighter mayday and LODD.

The video companion to this report includes a side-by-side comparison of similarities between both line-of-duty incidents.

The video timeline

Forensic data was compiled to generate a comprehensive video fire timeline, including forensic lightning strike data, 911 calls, fire dispatch/operations audio, mayday audio, forensic Apple Watch GPS/movement/biometric data, electronic self-contained breathing apparatus data, portable radio movement/channel data, advanced computer fire modeling, field fire testing, large-scale fire testing, 3D building measurement scans, drone footage, and incident photographs/video.

Fire Dynamics Simulator, a Computational Fluid Dynamics computer fire modeling program, was used to gain a better understanding of the flow of heat, smoke and fire gases throughout the residence.

This timeline video concludes with 5 specific educational points that were developed because of the ATF analysis, including a side-by-side comparison of similarities between both line-of-duty incidents.

The similarities between the 2018 fire and the 2021 fire

In these separate incidents, both Firefighter Flynn and Captain Laird were suppressing flames on the first level when the floor beneath them collapsed, causing them to fall into the burning basement and crawl space below. The floor collapse occurred above the location of the CSST gas line. Both firefighters immediately transmitted mayday calls for assistance, however, they were unable to self-extricate. The time frame and circumstances of both LODD incidents are similar and warrant review to prevent future similar incidents.

Lessons learned

With the support of Celeste Flynn and the HCDFRS, the ATF Video Timeline LODD Analysis of Firefighter Nathan Flynn is offered as an educational tool for the fire service and fire investigation community.

For additional details:


This article is based on content in the
Aug. 10, 2023 InfoGram.

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