There are a ton of factors to consider when determining an action plan at a structure fire, so it is imperative to gather enough information to make the right call on a mode of operation. During the 360 size-up, clues surrounding the exterior of the structure help to make an attack plan, but to get a complete picture, the efficient incident commander (IC) needs to see what’s going on inside the structure. It may take some time to get an initial crew assembled to retrieve that information; time can be saved by performing the size-up with a thermal imaging camera (TIC) (see Photo 1).
Thermal Imaging 101
The inception of thermal imaging usage for firefighting began with the Royal Navy/Shipboard firefighting. It was this application that started the use of thermal imaging within the fire service, and it migrated to land based units. The concept was this: All objects have a certain temperature and emit waves of energy called infrared radiation (IR). Now, for most of us in the fire service, we are what I like to refer to as “End Users”; we want fast, accurate results, and, for the most part, we don’t care how we get them. However, as a culture, we should have a better understanding of how these results are obtained. So, here is the simple version: Hot objects will emit a higher amount of energy than cold objects; a thermal imager translates these energy levels into a viewable image, which shows a “heat picture” of a scene (see Photo 2). On the screen of the TIC without color, hotter objects are whiter, cooler objects are black and those in between vary in shades of gray. Because the IR radiation is not blocked by smoke, the TIC is a useful tool by firefighters to find victims, locate the seat of a fire and catch structural hazards earlier in the incident, lowering the risk level of interior fireground operations. Seems simple, but there is a bit more to it for the end users to grasp when it comes to TICs.
For example, how much does the average “firefighter” know about fire behavior? In my home state, the entry level “Firefighter I” class is more than 160 hours, with only three hours devoted specifically to fire behavior. Firefighter II is more than 110 hours with no specific fire behavior training. Fire Officer I and II: 108 hours, no fire behavior training. So when it is totaled up, the amount of true formal fire behavior training the average firefighter gets is less than 1%...and the absolute definition of our profession means that we are “experts” with fire…but are we?
Our neighborhoods are becoming inundated with larger, elaborate residential dwellings, all featuring large open spaces, multiple void spaces, increasing fuel loads and lightweight building materials. Each one of these factors has led to faster fire propagation, shorter time periods before flashover conditions, rapid changes in fire dynamics, and much shorter times to total building collapses. In short, we are experiencing volatile fireground behavior in disposable buildings. Having the TIC during the size-up can help to spot these issues without committing troops into a position that can lead to disaster (see Photo 3).
Taking this into consideration, it is important to understand what the TIC is telling you. This poses a significant risk to firefighters, because if the IC does not understand exactly what the picture is telling them, then there is a tactical decision being made without all of the facts! There are some basic rules on how the TIC operates:
Rule#1: Cameras measure contrast: Contrast is based upon the difference in temperatures within the objects the TIC sees. Remember that many materials within a structure fire have different levels of density, which will allow these materials to absorb and retain heat at differing rates.