I’ve read about and heard from a few firefighters who have told me that they were in a room which flashed.

The mere fact that they are able to relate such an experience is almost always a clear indication that a flashover did not occur.

Certainly some type of catastrophic fire event (CFE) took place, but in
all likelihood, no one survives a flashover and lives to tell about it.


So what happened? 

A trick question that always gets my students is:  Does it really matter what type of CFE it truly is? 

The answer is hell yes!  Why?

If we want our crews to survive, we need to constantly be aware of the what’s going on inside the burning box we’re crawling through.  Different
CFE’s give different clues as to what will be occurring next. 

Recognizing these clues will make the difference between crawling out of the structure, or being carried out by your brothers.  You have to have the smarts to look for, recognize, and react to the constantly changing situation of an aggressive interior attack.

In the spirit of training, here is a cool video of a catastrophic fire event taken from five feet outside the door of the room.  Watch it closely as it develops, then make your guess as to what type of CFE it may be.

Above all, learn to recognize these clues and keep your brain engaged constantly next time you’re crawling through that burning

FlashoverTV is powered by FireRescue1.com

This is a flashover as viewed from 5 ft away from the doorway. The fire was allowed to continue on purpose to achieve the flashover. I
captured the footage with my special camera. A secondary smoke explosion in the attic blew two sheets of tin off. I use the footage for training. Hope you can use it for instruction as well

John Mitchell is a fire Lieutenant and paramedic in suburban Chicago. He is a fire and EMS instructor, certified fire investigator and Chicago Blackhawks fan. He is the editor of FireDaily and co-creator of FirefighterNetCast.


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ummm....if you can open and close the nozzle, please explain why you couldn't open it....and leave it open.
I agree....YET...if I were in a house fire, that was about to flashover on me and/or my crew I would open the like and let it eat (remember , there SHOULD also be searches going on in the house) so if you choose to NOT put it out and let it control the entire house....you have failed the citizens AND other members performing their jobs also.

I would like to never get burned again......BUT, I will willingly take a "Larry the Lobster" burn over subjecting myself, or others to being engulfed in a flashover and being burnt to a crisp.

Just MY take on it....thats all
It is all about the situation, searches may or may not be going on, and personally I'm not going to sacrifice myself, lobsterized or not, for property. Easier to backout and regroup than chance serious injury or worse. It depends entirely on the situation presented with, staffing, etc.
The point to pencilling is that you ensure that you don't upset the thermal balance and spread steam from floor to ceiling throughout the entire structure prior to extinguishing the fire. If there are searches going on, the victims are probably going to be on the floor, in an area that is temporarily survivable due to having relatively fresh and cool air.

If you nail the fire without cooling the overhead first you will probably upset the thermal balance and fill up the victim's formerly survivable space with superheated steam.

Pencilling prevents flashover while also preventing steam burns to the victims and the members. It is not a "choose to NOT put it out" technique. It's just a smart way to prevent flashover and also prevents firefighting-induced injuries to the victims and the members. That is the exact opposite of failure.

We need to work smarter, not harder. Good pencilling techniques fall into the "smarter" category.
You can leave the nozzle open, but it's not smart. If the fire is unvented, then it is especially not smart to just open up on the fire.

Pencilling is not just a way for a flashover simulator to keep burning. It is a way to maintain the thermal balance and maintain a survivable air space at the floor level while preventing the superheated gases at the ceiling level from igniting.
well, can you explain how allowing a room to continue to burn (pencilling to prevent flashover....yet allowing a room to continue to free burn) might assist those crews searching above the fire?

Altho not "impossible", most civillians in the free burning room that is about to flash will be deceased at the point that we (fire personnel in turnout gear and breathing apparatus) are feeling so much heat that we are thinking about 1)leaving or 2) putting the fire out so we can survive.......and I can't for the life of me, grasp the concept of allowing a room to free burn while searches are continuing in other parts of the house (to include ABOVE the fire room(s) )

P.S. even tho I am apparently not in the "smarter" category.....I do understand what the "pencilling" technique is, and what it does ......I also understand what allowing a fire to continue to burn does.

And in my not "smarter" opinion.....any lineman with a charged working hoseline that allows themselves or others to be caught in a flashover because of their failure to extinguish the fire should suffer the wrath of all surviving members operating on that fire........I refuse to accept that kind of failure, no matter what kind of spin you choose to put on it.
Pencilling doesn't allow the fire to "free burn", it prevents the charged upper layer from igniting.

"The point to pencilling is that you ensure that you don't upset the thermal balance and spread steam from floor to ceiling throughout the entire structure prior to extinguishing the fire."

Your statement "...and I can't for the life of me, grasp the concept of allowing a room to free burn while searches are continuing in other parts of the house..." is a classic straw man fallacy. No one except you made that statement, I didn't recommend pencilling as an alternative to extinguishment, and my previous statment made it pretty clear that pencilling is done prior to extinguishing the fire, not instead of it.

It seems that everyone else here grasps the concept of pencilling as a flashover prevention and crew safety measure pretty well.
I believe Vincent dunn is the person doing a full-day lecture on tactics/safety for our fire dept. in June...should be good.
wow!! great video!!! it's amazing how fast a flashover can happen. thank you for sharing.
and I view extinguishment as flashover prevention AND performing our (or at least my job)
...and if you just extinguish a sealed-up pre-flashover fire like the one in the video, you'll probably - and unnecessarily - steam burn your crew.

The rest of us will pencil, ventilate, then extinguish, keep the damage contined, and keep the survivable parts of the structure survivable for any civilian victims. We're a lot less likely to get steam burns, but feel free to do it your way. I sincerely hope that you - and your company - don't end up in the burn unit.
CFBT is the mechanism by which we strive to provide every firefighter with the necessary understanding of fire behavior, combined with realistic training in proven and practical techniques, that will enable them to safely and efficiently extinguish structural fires under varying conditions.

Implicit in the above definition is the application of gas cooling hose stream techniques using adjustable fog nozzles; techniques that were developed and pioneered by Swedish and British firefighters in the mid 1980’s. During this time, CFBT trainers began using basic steel shipping containers, loaded at one end with timber, to replicate the production of flammable fire gases, with open and shut vents added to control air flow. Inside these ‘cells’, firefighters could not only view the early stages of fire growth but examine first hand the production of unburnt products of combustion combining with flammable gases given off by the pyrolysing timber.

Firefighters were able to witness the transformation of smoke to flame as pockets of unburnt fuel in the smoke reached ignition and turned to flame. As the session progressed, the firefighters would observe a ‘flashover’ in the fuel-loaded end of the cell, witnessing the sudden but sustained transition from a developing, to a fully developed fire. During their time in the cell, the firefighters would crouch low as super heated flammable gases billowed out of the end of the cell, only inches above their helmets and as the temperatures increased, fingers of flame would move through the smoke.

Using their hose-line, they would direct short pulses of water fog into these gases, lowering their temperature and causing any flames to disappear. As they cooled the gases, the layer of fire gases would contract away from them, maintaining their visibility. Under the watchful eye of their instructor, they would practice their techniques, always observing the variance between too much or too little water, mindful of the steam generated if they misdirected their pulse against the superheated linings of the cell. These are the skills that they would take to their first fire call.

Not only other Scandinavian countries such as Norway, Finland and Denmark trialled the techniques but they also spread to other parts of Europe such as Holland and Spain. Firefighters from the United Kingdom were among the first to investigate these new techniques and by the mid 1990’s a number of British Brigades were training this way. The introduction hastened, as always seems to be the case, by the death of several firefighters from different parts of the country. All victims of extreme fire behavior. Since then many Brigades worldwide, have introduced CFBT into their training regimes, making it a compulsory part of their firefighter training.

CFBT brings together the study of fire behavior (or more aptly described ‘extreme’ fire behavior) and realistic carbonaceous fire cells and props. For the complete learning experience the two are inseparable. Once a firefighter understands the key fundamentals of how a fire grows and interacts with the many variables present within a compartment they can then observe the various phenomenon in a safe and tested environment. Better still, they can practice and prove the validity of the gas cooling techniques designed to combat the dangers of Flashover, Backdraft and Fire Gas Explosions.


The opening page of our CFBT (compartment fire behaviour training) program, and a short vid to demonstrate. The video is of NSWFB instructors completing a controlled burn with CSIRO officials taking data, but it shows how effective the gas cooling techniques are. Food for thought, cheers guys.

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