Extremely large single-family houses, lightning strikes causing the corrugated stainless-steel tubing (CSST) lines to arc and ignite escaping gas that sparked combustibles and burned for an extended time in unknown voids.
Those were among conditions Howard County Fire Lt. Nathan Flynn faced on July 23, 2018 and Frederick County Battalion Chief Josh Laird on Aug. 11, 2021. For both, it would be their final alarms.
They both called 'Mayday' after falling through the first floor. Flynn landed in a crawl space while Laird went into a burning basement.
ATF Special Agent Adam St. John shared the analysis Thursday at a training program jointly hosted by Howard and Frederick counties.
"ATF personnel utilized engineering analysis methods including 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," he explained in the document.
The house in Howard County was 8,400 square feet, while the other was 5.400. Both featured open floor plans and n neither were equipped with sprinklers. They were significantly larger than firefighters are used to.
“A basement fire that is open to the rest of the residence will have considerably more ventilation to support fire growth when compared to a fire on an upper floor that becomes ventilation limited much faster,” according to the report.
Investigators determined lightning struck a tree outside the Howard County home and followed through the ground to an underground propane storage tank. It energized the distribution system causing the CSST in the crawl space to arc to a nearby grounded object. The high-temperature arcing resulted in a hole in the line that resulted in wooden floor joints and combustibles catching fire.
The residents called 911 approximately 30 minutes after the lightning strike when they noticed smoke in their living room. Exactly 60 minutes after the lightning strike, Flynn called a Mayday after he fell through the living room floor into the burning crawl space below, according to the report.
A similar scenario played out three years later in Frederick County when lightning struck the chimney, energized the system and caused the failure of the CSST.
The flooring in both houses above the burning crawl space and basement was comprised of several layers of wood sheathing, cement board and thick, non-combustible Italian tile.
That tile and cement board masked the heat signatures from the fully involved burning below so firefighters were unaware of what was happening. Fire was only visible on the first floors, St. John pointed out.
During the analysis, investigators learned that Flynn was wearing an Apple Watch.
Celeste Flynn said she got her husband’s watch and wedding ring at the medical examiner’s office the morning he died.
The following day when a friend brought her husband’s truck home, she looked at his phone and saw the data. The watch stopped due to the extreme heat conditions, but started working again when Flynn was moved by the rapid intervention team.
“It showed his last movements,” she said Thursday afternoon, adding that she told investigators about the data when she visited the house where her husband perished.
Investigators noted: “The movement and temperature data recorded by the Apple Watch was consistent…with data recorded by Firefighter Flynn’s SCBA and portable radio during the same timeframe.”
St. John said he hopes the detailed information in the analysis will be used throughout the country to prevent similar tragic situations.
Since the tragedies, Flynn and Sara Laird have made it their mission to not only learn about CSST but educate politicians and firefighters about the danger associated with them.
Howard County and the National Institute for Occupational Safety and Health (NIOSH) also conducted their own reports.
Likewise, Frederick County has issued its report and recommendations while the NIOSH document has not been completed.
