Forensic Files - Season 8, Episode 42 - Flashover - Full Episode | Forensic Files

in a crowded london underground station a small routine fire suddenly erupts into a deadly inferno and kills 31
people dozens more are injured a team of forensic experts searches for clues to the cause of the blaze and
finds that the fire seemed to defied the very laws of physics to unravel the cause of the mysterious
fire investigators would need to recreate a historic train station inside a modern
computer [Music] [Applause] [Music] [Applause] the sprawling london underground is the
largest and oldest subway rail system in the world but on the evening of november 18 1987
commuters are unaware that disaster lurks beneath them at 7 30 p.m a passenger at the historic
king's cross station sees a flicker of flame underneath a heavily varnished 50-year-old wooden escalator
the london fire brigade is dispatched it seems to be a routine call an everyday call to a fine and escalator
something we were receiving probably 20 or 30 times a month so it was no big deal
fire captain roger kendall one of the first to reach the scene waits above ground for his supervisor to report
we will wait for message to come back to say either we're all going home or we may need a bit of equipment
trains continue to come and go despite the minor commotion musician ron lipsius arrives at the
station on one of those trains we've noticed these two men i don't think they were in uniform but
they were blocking physically blocking entrance to the wooden escalators on our left which are the ones that
directly go to piccadilly train so we thought oh that's strange and it was actually a tiny bit hazy
in there too we noticed that too a little bit smoky firemen see a small fire burning about halfway up one of the
escalators bringing passengers from the tracks up to the ticket hall a very experienced fire officer looked
down the escalator and assess the fire as being it's about the size of a cardboard box
but firefighter colin townsey spots something he believes is dangerous he calls firefighters above ground
asking for more equipment and saying people are in danger he through his experience had seen
something going on above the fire around the fire whatever he could see he knew that something bad was about to happen
on the train platform below passengers are now being urged to get out the quickest escape route is up another
bank of escalators near the fire these two lead directly to the ticket hall as soon as we got near the top
we noticed it was really dark and smoky at that time there was this policeman with a
flashlight and saying hurry up don't don't just stand there but the warning comes too late
as soon as i went through that turnstile some kind of explosion happened when i was halfway up that escalator a
sheet of flame erupted and shot across the top of the whole of the top of the exit from that escalator so i was just
moving up towards a wall of fire searing flames rip up the escalator and into the ticket hall incinerating
everything in their path they were like these living things in up in the corner by the ceiling and they
were huge and it was awesome and i just took one look at that thing and i just i felt like an ant i mean it felt like
this thing is like a monster there was just a complete rush of thick black smoke from the subways
right all the subways leading out onto the main roads around the station and it was right at that moment we realised
that the flashover would occur flashover is a virtually instantaneous spread of fire everything flammable
ignites simultaneously so from two minutes it had gone apparently the size of a cardboard box
to a major disaster firefighters tried desperately to get inside the station but are driven back
by the intense heat and smoke firefighters were collapsing left right and center
the heat down there had made some of them urinate themselves with fear and when they came out to the top they
weren't capable of moving again a lot of them were collapsing in the heaps ron lipsia stumbles into the chaos
outside and for the first time realizes he is badly burned i looked at my hands and there was this
skin just hanging down like like when a snake sheds its skin firefighters battled the blaze for an
hour when it is finally out 31 people are dead and more than 70 others are injured
among the dead is firefighter colin townsley colin was found with two two members of
public that he'd obviously pulled along the tunnel trying to get him out to safety
two people that he'd obviously tried desperately to get out of that inferno and it cost him his life
the king's cross station is shut down the london underground is crippled thousands of commuters are stranded
through the smoky haze of the ruins a mystery emerges why did a fire the size of a cardboard box explode into a deadly
inferno in a matter of seconds in the hours following the deadly king's cross fire
investigators from england's health and safety executive sifted through the charred station looking for clues
but finding them in the ruined ticket halls and tunnels wasn't easy there is nothing quite like seeing a
fire scene firsthand to give you a full appreciation of the the devastation that
has taken place and also to give you a feel for how the fire might have developed
they needed to answer two critical questions what sparked the fire and how could it appear so suddenly and erupt
into a fatal blaze that claimed 31 lives nearly a million people relied on the underground each day
they needed to know if the system was safe this is the stuff of nightmares being
trapped by fire underground i mean it really is something that tugged at the heartstrings of ordinary londoners it
was on the front pages of every newspaper obviously for several days and there was enormous demand to find
out why it had happened investigators started where the flames were first spotted the escalator this
was the lowest point of the fire indicating the fire had started there and burned upward
no accelerants or other indications of arson were found underneath the escalator investigators
found accumulated grease litter and debris ideal fuel for starting a fire they also found evidence of many
previous small fires started by smoldering matches and cigarettes the actual source of ignition
is assumed to be a dropped match which had not been extinguished and if that had come in contact with the
grease on the running track of the escalator the grease would have ignited very very
easily investigators speculated that someone on the escalator lit a cigarette and
carelessly tossed away a burning match but could one match cause such a deadly fire
they tried dropping matches from heights they found that a match would be able to
in certain circumstances to light the grease on the escalator but in the tests the fire was slow
burning and didn't explode up the escalator there was all sorts of theories as to
how this could have happened so fast and amongst those theories everyone was desperately searching for the truth
meanwhile journalists uncovered dozens of previous escalator fires in the london underground
to some extent the underground had been extremely lucky for 50 years they had a lot of these wooden
escalators they all suffered from similar problems there'd been a series of escalator fires
it was reasonably predictable that there was going to be a serious one after a fire two years earlier at
another station investigators said the system's aging wooden escalators were a disaster
waiting to happen but why did this fire turn into a deadly inferno there was a lot of thoughts about the
the trains actually fanning the flames because it was extremely clear whenever a train came into that station that the
smoke that was bellowing out of the subways where i would increase but measurements of air flow in the
escalator area showed this would not affect a small fire on the steps other theories blamed the varnish on the
wooden escalator and multiple layers of paint on the ceiling there are examples of fires in
old buildings in in the uk which have been painted regularly every three or four years and these buildings
are 100 years old and if the paint becomes involved it becomes an inferno very very quickly because paint
delaminates blisters and burns rapidly when they did some tests when the hse did some tests on the ceiling page
something that was not damaged they couldn't make the flame spread fast enough along it and that's when they
started to question what else could be the main fuel and that's when they came to talk to us to see if we could do
anything to help what do you think of these results now turned to a team of forensic
mathematicians at the investigative firm of cfx their goal was to create a computer
simulation of the deadly fire using computation fluid dynamics or cfd this was the first time it would be
applied to the behavior of fire but they believed it would work because heat and air flow like fluids
hot air causes the the fluid to expand and it makes it lighter and then it tends to rise relative to the other
ambient fluid around and so then you see smoke rising smoke plumes and that's the kind of thing that we can
simulate with the software because it really is just simple fluid mechanics but could it solve the mystery of the
king's crossfire [Music] to recreate the deadly king's crossfire in a virtual world the station was
measured and mapped onto a computer grid then factors such as the fire's point of
origin air flow and types of wood and paint were added to the simulation but the result showed
something unusual according to the computer model the king's cross fire had literally defied
the laws of physics the hot air around the fire did not rise instead it clung to the steps
we saw that the hottest air seemed to be lying down in the escalator trench which
was unexpected to me anyway and the other people from hse who came to look at those early simulations
i think the initial reaction was it was possible that i've got gravity upside down which you can do in the computer so
maybe i'd made things go the wrong way was it a human error could we have input the data incorrectly
could there be a bug in the program the investigators entered all the data again the results were the same we did
all the checking and did more runs and and still found that the hottest air was lying down in the trench eventually
spiraling up over the ceiling but initially lying down in the trench it was a startling but significant clue
the hot air and gases should have risen up to the ceiling but the escalator stairway appeared to
channel them into the ticket hall and that made us start to think about maybe the wood of the escalator could be
the main fuel if the flames are lying down in the trench they're preheating the wood ahead of the main flame front
and therefore once it gets going it could move very very rapidly they called what they saw
the trench effect but it was merely a theory using untested computer simulations and it was
inconsistent with typical fire behavior if you have a fire burning in the open on a flat surface
the fire feeds itself with air by drawing it in from the outside it's created by the dynamics of
the flame itself the buoyant gases rise creating slight pressure differences which draw air into low at a low level
but on an incline that airflow is restricted on the uphill side to examine this a rough model one tenth the size of the
escalator shaft was placed flat on the ground the result was a slow vertical burn
but at a 30 degree angle the angle of the king's cross escalator the flames leaned into the shaft at an angle and
raced upwards in the confined trench the fire could only draw air from below creating a draft
because the air can't come round the fire it has to come effectively through the fire
investigators then ran a bigger test on a one-third size model of the complete king's cross station
if the trench effect worked this time it would prove their theory was right in the match of three or four seconds
the flames went from the upright to being lying uh along the escalated trench and from then on it was just as
we predicted which is very gratifying it was clear that the previously unknown phenomenon
called the trench effect was real people suddenly saw a fire and said now we understand you've got an
explanation of what it is it's now all obvious it fits together the jigsaw fits together
perfectly the investigative team now had compelling evidence that would reveal the deadly sequence of events
[Music] for months a government inquiry into the disaster at the king's cross station
fire had struggled to find out how a small fire had exploded so quickly and killed 31 people
[Music] now a team of forensic experts said new computer technology provided the answers
the computer graphics helped us to understand what had taken place and also to present the results to people
who were maybe not as familiar with the technology that we were using so we could explain the results to them very
simply sometime around 7 15 p.m a smoker at king's cross carelessly dropped a match on the wooden escalator
the match fell between the steps and the side of the escalator into the gear bed
below it was lined with years of grease and debris a slow burning fire began at 7 30 p.m
the flames became visible and underground staff called the fire brigade at 7 40 p.m
two firemen saw the low-lying flames and at first assumed it could be easily extinguished
the fireman who was walking down escalator number six and looked across to escalator number four approximately
one minute before flashover and described the fire as being relatively small but then the fire spread across the
steps the bottom of the trench it could only draw oxygen from one direction from below
this was the trench effect and once you had established a fire across the width of the escalator it meant that the
flames were deflected into the trench and began to flow up the treads the risers and exposing the
balustrades to very high levels of heat flux then it just switches and flips over to stick to the floor
of the escalated trench from there it pre-heats the wood the hot gases are going up the escalator trench ahead of
the flame they're heating the wood quite considerably gets quite hot even though there's no flame there it's
sucking up the air from below like a chimney wood which is what it needs to do and that would tend to flatten the
flames down in the early stages as well which would start this effect off of the
trench effect the escalator trench acted as a chimney made not of brick but of highly
flammable wood at 7 45 a torrent of superheated gas rushed up the escalator priming everything in its
path to burn it was called a flush over the sudden movement of the fire up up the escalator
was called the flashover as it burst into the booking hall at the top the hot gases and flames exploded into
the ticket hall feeding off years of thick paint on the walls and three tons of varnished wood
on the escalator below the cavernous room was a death trap those people would have died extremely
quickly and if there's anything if there's any comfort there it is the comfort that they didn't suffer for very
very long at all they were taken extremely quickly the government's board of inquiry
accepted the new science of the trench effect and found it had caused the disaster
there was a general sense amongst people that really the underground should and could have prevented this
i mean there were resignations of course but um i think there was a sense that the underground
hadn't really been on top of the problem of fire underground to ensure such a tragedy would never
happen again all wooden escalators were eventually removed from the system flammable grease and debris
are regularly removed from beneath escalators and the underground staff is now required to be trained in fire
evacuation procedures those directly affected by the fire can take some comfort that science
explained the mystery that changed their lives it ruined the life that i was having
my life was going certain ways perfectly happy with it and it totally ruined that life but i
i got onto a different life i don't use the underground i've used the underground since
that night at king's cross i'm not saying it's not safe because i believe it's far safer now than it ever
was but for me personally i'm happy to avoid it those who solved the mystery of the
king's crossfire no their intensive efforts will help save lives there's also plaque in the booking hall
to the memory of the people that died then you know i often just stop there and stand and read it and just spend a
quiet moment in reflection because there was a human tragedy there which sometimes can easily be forgotten
so i feel strange going back there and a little shiver i enjoyed seeing the computer model be
used in a way that was good so people could understand what had happened and therefore try and prevent it happening
again it's opened a whole new line of study on flame spread that perhaps we've taken much longer to
achieve if we hadn't had the experience of kings cross [Music] god [Music] you

A fire erupted in Kings Cross Station in London, killing 31 people and injuring dozens more. Investigators pinpointed the cause of the fire, but it took state-of-the-art technology and fluid dynamics experts to explain why it became a deadly inferno. Forensic Files is the longest-running true crime series in television history. Evidence and interviews with experts help solve real crimes, disease outbreaks and accidents around the world.

Brief Summary

The King's Cross fire killed 31, revealing critical fire safety flaws in the London Underground.

Key points

King's Cross Fire Tragedy. A small fire escalates into a deadly inferno, claiming 31 lives and injuring many.
The Trench Effect. Investigators discover a phenomenon that contributed to the rapid spread of the fire.
Lessons Learned. The tragedy leads to significant changes in fire safety protocols in the underground.

Episode highlights

Episode quotes

I felt like an ant, this thing is like a monster.

A survivor's emotional reflection on the fire's intensity.

4:28WatchDec 16, 2021

Tension

75/ 100High tension

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