Here it is: the emergency that you feared, the one that you dreaded, the one whose potential helped you justify funding your thermal imagers (TIs)."Engines 2, 7, 3, Ladder 2, Quint 11, Ambulance 16 and District 1: Respond to a residential fire, with children trapped at 4567 Eighth Street. That's Engines 2, 7, 3, Ladder 2?."
Here it is: the emergency that you feared, the one that you dreaded, the one whose potential helped you justify funding your thermal imagers (TIs). You know you are properly equipped: you have NFPA-compliant turnout gear and helmet, a new SCBA, recently tested search lines and hose lines, and your new TI. You have it all. The question remains: are you ready to use it all?
Are you comfortable and competent?
Your TI will make your search efforts easier, but that does not mean they will be easy. To have the highest probability of success, you need to be comfortable and competent with your TI. As you know, there is not an indicator on the TI screen that circles your victim and flashes the word "HUMAN"; the TI is designed only to detect relative differences in surface temperatures. This means a TI cannot tell you what you are viewing, only that you are viewing items of relatively different (or similar) temperatures. Determining what you are viewing is the challenge that requires practice.
Shape and heat anomalies
Sometimes, it is not difficult to interpret an image on a thermal imager. Most objects and situations are not complicated or camouflaged. For example, take your TI into the day room at the station and have a partner sit on the couch. It should be relatively easy to determine the image of a person sitting on a couch; the forms of the head, torso, and legs should be clear. However, structure fires are complicated, and potential victims are often camouflaged. In search and rescue operations, the most difficult variable in a search may well be the nature of humans. As you well know, children try to hide under beds and in closets, while adults try to escape. As a result, search efforts can be frustrated because the victim probably will not present his full, recognizable figure (as your partner did on the couch).
Keep in mind that children may cover themselves in an effort to hide. As a result, you will not get a full image of the body. You will instead have to look for "heat anomalies," which are heat signatures that are out of place, or unexpected, in their environment. Imagine a heat signature under a bed. This is unexpected, and therefore an anomaly. It may not obviously be a child, but the heat signature's location should cause you to investigate further. One member of the search team should enter the room, perform a sweep under the bed to determine if this is a victim, and then begin the rescue.
Adults may not hide from fire like children, but they still can present challenges to the search team. Adults (or children) may not even get out of bed before succumbing to the toxic effects of smoke. Normally, we might expect a heat signature on the bed, but the thermal image may not present as an obvious person. Most people sleep under sheets and blankets to stay warm at night. Every layer that keeps cool air off the person's skin also keeps the person's body heat from your TI; thicker layers mean less heat anomaly for your TI to pick up.
It is reasonable to expect that the person still in bed may appear as a lump that displays as a slightly different shade (depending on overall room temperatures). While a lump may be just a mound of covers that were tossed aside in a rush to evacuate, it also could be a person who did not get the chance to evacuate. Because beds can pose such difficulties as hidden heat signatures, fire departments should consider a standard policy requiring that all beds be physically searched (on top and underneath) to ensure that victims are not missed.
Victims do not always display as white