Arc Mapping: A Review of Findings and a Reply to the ATF Laboratory

There has been a lot of debate in fire investigation industry recently regarding Arc Mapping.  NAFI’s mission is to increase the knowledge and improve the skills of persons engaged in the investigation and analysis of fires, explosions and arsons, or the litigation that ensues from such investigations. The opinions expressed in this paper do not necessarily reflect the opinion and beliefs of NAFI. Over the next three weeks, we will be sharing different views on Arc Mapping with our members and the industry – it is up to you to draw your own conclusions.

Week 1 – Arc Mapping: New Science or New Myth?
Week 2 – Arc Mapping as a Tool for Fire Investigations
Week 3 – Arc Mapping: A Review of Findings

The ATF Laboratory recently issued Special Bulletin No. 2 which offered a series of objections to the arc mapping review presented by this author earlier this year. This paper reviews the original research findings and explains the context of these findings. It then addresses in detail the comments made by ATF, and further addresses the concerns about arc mapping as currently used in the field. It reaffirms that the original findings are correct. It also shows that a new “ellipse” method proposed by the ATF for origin determination from arcing locations is not technically sound.

Download the complete paper here


Arc Mapping as a Tool for Fire Investigations

There has been a lot of debate in fire investigation industry recently regarding Arc Mapping.  NAFI’s mission is to increase the knowledge and improve the skills of persons engaged in the investigation and analysis of fires, explosions and arsons, or the litigation that ensues from such investigations. The opinions expressed in this paper do not necessarily reflect the opinion and beliefs of NAFI. Over the next three weeks, we will be sharing different views on Arc Mapping with our members and the industry – it is up to you to draw your own conclusions.

Week 1 – Arc Mapping: New Science or New Myth?
Week 2 – Arc Mapping as a Tool for Fire Investigations

ATF Fire Research Laboratory Technical Bulletin
Arc Mapping as a Tool for Fire Investigations

The purpose of this Technical Bulletin is to address statements that are contained in Arc Mapping: New Science or New Myth?, which was presented at the Fire and Materials Conference in February 2017. The paper’s interpretations and analysis of the published literature, the limitations it places on the process of arc mapping, and the conclusion that arc mapping is applicable to less than 1% of fire scene investigations are misleading. This bulletin addresses some of these issues.

Download the entire technical bulletin here.


St. John’s School Fire – October 28, 1915

The St. John’s School fire was a deadly fire that occurred on the morning of October 28, 1915, at the St. John’s School on Chestnut Street in the downtown area of Peabody, Massachusetts. Twenty-one girls between the ages of 7 and 17 were burned or crushed to death while attempting to escape the fire.

More than 600 children were in the building when the fire began in the basement of the school building. There were no fire escapes on the outside of the building, but instead those inside were forced to use wide stairways at either end of the interior which led down to the front exit. Mother Superior Aldegon, who led the Sisters who taught in the Catholic school, sounded a fire alarm and began the routine fire drill procedure.

This procedure should have led to the children and teachers leaving the building through the stairways to and out of a rear exit. However, as smoke thickened and the fire came closer, they ran for the front door instead, and became jammed in the vestibule. The fire broke through to the vestibule from directly under the front entrance and the vestibule, now crowded with pupils, was enveloped in flames. The fire rapidly swept through the three-story brick and wooden building, fully engulfing it in less than five minutes.

With their exit blocked, many of the children escaped through first-floor windows or jumped from those on the second and third floors. Not all were able to escape, however; the bodies of the 21 victims were found after the fire subsided, huddled together and burned beyond recognition, on the inside of the school entrance. The Sisters of Notre Dame who taught at St. John’s aided the children trying to escape, some by dropping the students into coats and blankets being used as life nets. These actions were credited in saving many lives. Two of the nuns were injured, one suffering serious burns; however, none of the adults were killed.

As a result of this fire, Peabody became the first city to pass a law that said all doors (in public buildings and school) must push out.

Source: Wikipedia

1904, June 15th:  River excursion ends in tragedy

More than 1,000 people taking a pleasure trip on New York City’s East River are drowned or burned to death when a fire sweeps through the boat. The General Slocum disaster was the New York area’s worst disaster in terms of loss of life until the September 11, 2001 attacks. It is the worst maritime disaster in the city’s history, and the second worst maritime disaster on United States waterways.

The riverboat-style steamer General Slocum was built in 1890 and used mostly as a vehicle for taking large groups on day outings. On June 15, the St. Mark’s German Lutheran Church assembled a group of 1,360 people, mostly children and teachers, for their annual Sunday School picnic. The picnic was to take place at Locust Point in the Bronx after a cruise up the East River on the General Slocum.

At about 9 a.m., the dangerously overcrowded boat left its dock in Manhattan with Captain William Van Schaik in charge. As the boat passed 83rd Street, accounts indicate that a child spotted a fire in a storeroom and reported it to Captain Van Schaik. Reportedly the captain responded, “Shut up and mind your own business.” But as the smoke became more obvious, crew members were sent to investigate. By this time, the storeroom, filled with a combination of oil and excelsior (wood shavings used for packing), was blazing out of control. The onboard fire hose, which had never been used, tested or inspected, did not work.

Captain Van Schaik made a fateful decision at this time. Instead of directing the boat to the nearest dock where firefighters could engage the fire, he pointed the boat toward a small island in the East River. He later told investigators that he did not want to risk spreading the fire to the dock and the rest of the city, but the strategy proved deadly for the passengers. Instead of grounding the boat on the sand, the boat crashed onto the rocks of the island’s shore.

At this point, other factors also combined to exacerbate the situation. The lifeboats were so firmly tied to the steamer that they could not be released. The life preservers had not been filled with cork, but a non-buoyant material that made them weighty. The children who used them sank to the bottom of the river. Other children were trampled to death in the panic. More people were killed when the raging fire collapsed some of the decks, plunging them into the fire.

In all, 630 bodies were recovered and another 401 were missing and presumed dead. A cannon was brought to the scene and fired over the river the next day to loosen bodies from the river mud. The boat’s crew, and officers in the Knickerbocker Company, owner and operator of the General Slocum, were charged with criminal negligence. However, only Captain Van Schaik received a prison sentence. He was supposed to serve 10 years, but was pardoned due to old age in 1908. President Theodore Roosevelt fired the chief inspector of the U. S. Steamboat Inspection Service in the aftermath of the accident; wholesale changes in the industry followed. A mass grave was set up in Queens for the victims and a yearly memorial was held to honor their memory.

Image: The Library of Congress – shows the mass of burned timbers and ruined metal, showing broken paddle wheels shaft.

May 17th, 1994: Fire engulfs Honduras prison

A fire in an overcrowded Honduras prison kills 103 people on May 17, 1994. An overheated refrigerator motor sparked the horrible blaze that raced through the outdated jail. Only a year earlier, a gang fight at the same prison had left nearly 70 people dead.

The prison, in San Pedro Sula, 100 miles north of the Honduran capital of Tegucigalpa, was largely devoted to housing gang members arrested in a recent crackdown. This new emphasis on jailing gang members resulted in a prison population of nearly 2,000, although the structure was built to accommodate only 800. The fire and explosion took place in a cell block that housed 186 prisoners belonging to the Mara Salvatrucha gang, also known as MS-13. The fire started in one of two small refrigerators located in the cell block at about 1:30 a.m. Prisoner Jose Lopez reported, “Everything happened fast. We woke up with our clothes and our beds in flames.” Guards reported that they had to fire their guns in the air in order to keep the prisoners from attacking the firefighters and escaping. Inmates claimed that the guards were preventing the prisoners from fleeing the fire.

As news of the fire became public, relatives of the prisoners began gathering outside the prison. Officials then placed the bodies of the dead in rows on the ground for identification, which was often made through their elaborate gang-related tattoos, before refrigerated trucks transported them to a morgue.

The Honduran government continued its anti-gang activity in the wake of the tragedy, but also took steps to prevent prison overcrowding.


Aluminum Phosphide-Based Fumigants as an Ignition Source


John L. Schumacher, MChE, PE, CFI, CFPS
Zachary J. Jason, PE, CFEI
Advanced Engineering Investigations Corporation, USA

Presented at International Symposium on Fire Investigation, 2012


Raw agricultural commodities, such as corn, soybean, rice and wheat, are typically stored in bins and silos prior to shipment. During storage, it is often necessary to protect the commodities from damage by insects and pests. A common protection method utilized is the addition of solid fumigant pellets or tablets to the commodity.

One of the most common solid fumigants employed is a blend of aluminum phosphide, ammonium carbamate and other inert ingredients. Aluminum phosphide reacts with atmospheric water and moisture in the commodity based on the following equation:

AlP + 3H2O = Al(OH)3 + PH3 + Heat

The reaction yields phosphine gas (PH3), which is highly toxic to insects, pests and humans. The reaction is exothermic, which means heat is generated alongside the other products. Phosphine gas has a lower flammable limit (LFL) of about 1.8% gas in air and can ignite spontaneously at concentrations above the LFL. The ammonium carbamate is added to the mixture to reduce the potential fire hazard by generating ammonia and carbon dioxide, which act as inerting gases. The carbon dioxide reduces the tendency of phosphine to auto-ignite in air. The decomposition reaction is as follows:

NH2COONH4 = 2NH3 + CO2

Improper application of the fumigant tablets or pellets can lead to fires. This paper provides basic product information, and discusses the chemistry, application methods, previous testing, and ignition scenarios associated with solid fumigants containing aluminum phosphide. A case study of a fire that occurred in a metal grain bin containing wheat will be presented.

Presented at International Symposium on Fire Investigation, 2012

Triangle Shirtwaist Fire – March 25, 1911

In one of the darkest moments of America’s industrial history, the Triangle Shirtwaist Company factory in New York City burns down, killing 145 workers, on March 25, 1911. The tragedy led to the development of a series of laws and regulations that better protected the safety of factory workers.

The Triangle factory, owned by Max Blanck and Isaac Harris, was located in the top three floors of the 10-story Asch Building in downtown Manhattan. It was a sweatshop in every sense of the word: a cramped space lined with work stations and packed with poor immigrant workers, mostly teenaged women who did not speak English. At the time of the fire, there were four elevators with access to the factory floors, but only one was fully operational and it could hold only 12 people at a time. There were two stairways down to the street, but one was locked from the outside to prevent theft by the workers and the other opened inward only. The fire escape, as all would come to see, was shoddily constructed, and could not support the weight of more than a few women at a time.

Blanck and Harris already had a suspicious history of factory fires. The Triangle factory was twice scorched in 1902, while their Diamond Waist Company factory burned twice, in 1907 and in 1910. It seems that Blanck and Harris deliberately torched their workplaces before business hours in order to collect on the large fire-insurance policies they purchased, a not uncommon practice in the early 20th century. While this was not the cause of the 1911 fire, it contributed to the tragedy, as Blanck and Harris refused to install sprinkler systems and take other safety measures in case they needed to burn down their shops again.

Added to this delinquency were Blanck and Harris’ notorious anti-worker policies. Their employees were paid a mere $15 a week, despite working 12 hours a day, every day. When the International Ladies Garment Workers Union led a strike in 1909 demanding higher pay and shorter and more predictable hours, Blanck and Harris’ company was one of the few manufacturers who resisted, hiring police as thugs to imprison the striking women, and paying off politicians to look the other way.

On March 25, a Saturday afternoon, there were 600 workers at the factory when a fire broke out in a rag bin on the eighth floor. The manager turned the fire hose on it, but the hose was rotted and its valve was rusted shut. Panic ensued as the workers fled to every exit. The elevator broke down after only four trips, and women began jumping down the shaft to their deaths. Those who fled down the wrong set of stairs were trapped inside and burned alive. Other women trapped on the eighth floor began jumping out the windows, which created a problem for the firefighters whose hoses were crushed by falling bodies. Also, the firefighters’ ladders stretched only as high as the seventh floor, and their safety nets were not strong enough to catch the women, who were jumping three at a time.

Blanck and Harris were on the building’s top floor with some workers when the fire broke out. They were able to escape by climbing onto the roof and hopping to an adjoining building.

The fire was out within half an hour, but not before 49 workers had been killed by the fire, and another 100 or so were piled up dead in the elevator shaft or on the sidewalk. The workers’ union organized a march on April 5 to protest the conditions that led to the fire; it was attended by 80,000 people.

Though Blanck and Harris were put on trial for manslaughter, they managed to get off scot-free. Still, the massacre for which they were responsible did finally compel the city to enact reform. In addition to the Sullivan-Hoey Fire Prevention Law passed that October, the New York Democratic set took up the cause of the worker and became known as a reform party.


1969, Jan 14:  Explosion rocks USS Enterprise

An explosion aboard the aircraft carrier USS Enterprise kills 27 people in Pearl Harbor, Hawaii, on this day in 1969. A rocket accidentally detonated, destroying 15 planes and injuring more than 300 people.

The Enterprise was the first-ever nuclear-powered aircraft carrier when it was launched in 1960. It has eight nuclear reactors, six more than all subsequent nuclear carriers. The massive ship is over 1,100 feet long and carries 4,600 crew members.

At 8:19 a.m. on January 14, a MK-32 Zuni rocket that was loaded on an F-4 Phantom jet overheated due to the exhaust from another vehicle. The rocket blew up, setting off a chain reaction of explosions. Fires broke out across the deck of the ship, and when jet fuel flowed into the carrier’s interior, other fires were sparked. Many of the Enterprise’s fire-protection features failed to work properly, but the crew worked heroically and tirelessly to extinguish the fire.

In all, 27 sailors lost their lives and another 314 were seriously injured. Although 15 aircraft (out of the 32 stationed on the Enterprise at the time) were destroyed by the explosions and fire, the Enterprise itself was never threatened.

The USS Enterprise was repaired over several months at Pearl Harbor and returned to action later in the year.


ISFI 2016 wrap-up

Last week was ISFI 2016 at the beautiful McCormick Ranch in Scottsdale, Arizona.

We had over 40 presentations on a variety of fire investigation science and technology topics! Thank you to all of our speakers and all of those who submitted high quality papers of their research and experience, we are so grateful for your desire to share and give back to our community. Over 125 delegates joined us from eight countries.

Gregory Corbett speaking at ISFI 2016

We also want to thank several individuals who contributed time and effort to ISFI 2016 – Gregory Corbett, Ron Hopkins, Vyto Babrauskas, Scott Davis, Wayne Chapdelaine, Kevin Lewis, and Jim Shanley. Without them, ISFI 2016 would have gone on, but it wouldn’t have been nearly as much fun.


Port Chicago Disaster, July 17, 1944

An ammunition ship explodes while being loaded in Port Chicago, California, killing 332 people on this day in 1944. The United States’ World War II military campaign in the Pacific was in full swing at the time. Poor procedures and lack of training led to the disaster.

Port Chicago, about 30 miles north of San Francisco, was developed into a munitions facility when the Naval Ammunition Depot at Mare Island, California, could not fully supply the war effort. By the summer of 1944, expansion of the Port Chicago facility allowed for loading two ships at once around the clock. The Navy units assigned to the dangerous loading operations were generally segregated African-American units. For the most part, these men had not been trained in handling munitions. Additionally, safety standards were forgotten in the rush to keep up frenetic loading schedules.

On the evening of July 17, the SS Quinault Victory and SS E.A. Bryan, two merchant ships, were being loaded. The holds were being packed with 4,600 tons of explosives–bombs, depth charges and ammunition. Another 400 tons of explosives were nearby on rail cars. Approximately 320 workers were on or near the pier when, at 10:18 p.m., a series of massive explosions over several seconds destroyed everything and everyone in the vicinity. The blasts were felt as far away as Nevada and the resulting damage extended as far as San Francisco. Every building in Port Chicago was damaged and people were literally knocked off their feet. Smoke and fire extended nearly two miles into the air. The pilot of a plane flying at 9,000 feet in the area claimed that metal chunks from the explosion flew past him.