Interior or Exterior: Where Do We Begin?

Some members of the fire service are experimenting with variations of what have become standard firefighting tactics in many departments – the “interior attack,” sometimes called an “aggressive interior attack.” The interior-attack concept calls for firefighters to stretch an attack hoseline into the involved structure, through interior hallways, stairways and rooms, until they encounter the fire area, where they attack the fire from the unburned to the burned area. This practice has served us well for decades and many firefighters, officers and chiefs have worked entire careers following this plan of attack.

More recently, FDNY members, along with Underwriters Laboratories (UL) and the National Institute of Standards and Technology (NIST), are conducting experiments involving live-burn evolutions. These experiments are taking a look at several important issues, such as the changing dynamics of fire, which is the increased use of plastics and other synthetic materials in the furnishings we routinely encounter at fires. This change in dynamics has resulted in a change in the “flashover” timeline and an earlier moment of flashover in burning buildings. This change can also result in firefighters being inside and at the point of flashover when they are beginning their interior attack.

Tactical issues

Some of the issues being examined are when ventilation should be conducted and when and where the first water should be used for the attack. One of the points made is that if we simply enter the building and penetrate to the edge of the fire area, we may be operating in an extremely dangerous area that could suddenly flash over.

This has been a basic tactic that many departments practice at structural fires. We arrive at a building with fire issuing from two front windows. Some of us pull our hoselines and some enter to locate the fire and vent the building. As the hoseline is being stretched, the ventilation of the building lets the smoke and heated gases rise up and out of the building or to vent horizontally as the hoseline advances into the fire area.

These tactics have worked well for many years, but are now being looked at from a risk-vs.-reward perspective. Controlling and limiting ventilation, they say, will decrease the chances of firefighters experiencing unexpected flashovers while operating inside the structure. Another issue is the initial application of water on the fire. For years, fire departments have been told to refrain from directing streams into burning buildings from the exterior because this tactic could drive fire and heat to other uninvolved areas of the building, spreading the fire and endangering trapped occupants.

During the live-burn experiments, the buildings were outfitted with numerous sensors that measured temperature, heat flows, toxic gas concentrations and other factors. Along with video recordings of the burning building, these sensors showed that contrary to our previous beliefs, the application of the first stream into the window of the fire room resulted in a decrease of temperatures and general improvement on conditions throughout the building. This “resetting” of the fire makes conditions more favorable for an interior fire attack and does not spread or increase the fire conditions. Additionally, it changes conditions where the firefighters will be beginning their interior fire attack and greatly diminishes the chances of a flashover occurring where they are working.

The recent experiments and their results, although limited, have shed a new light on the tactics that many fire departments use every day. Do 20 or 40 or even 100 experiments change what have been accepted as standard operating procedures (SOPs) for many years? The answer, of course, is no, not immediately. But some of the results are eye openers. They still leave me with questions:

• If we direct the first hoseline into a window of a burning room, will the nozzle team be able to move away from there and enter the building for the interior attack?

• Can narrow streams be used for this tactic or are smooth-bore nozzles required?

• Can other firefighters enter a building for search while the line is operating into the window of fire?

• If just one window is opened, could that condition allow or promote fire to be driven in that direction by an outside stream?

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