Monday, June 2, 2025

Transitional Fire Attack: Not Defensive, Not Aggressive, Just Effective

Back in the early 2010s, Steve Kerber from the UL Firefighter Safety Research Institute (UL FSRI) and Dan Madrzykowski at the National Institute of Standards and Technology (NIST) ran some important live-fire tests. They showed that applying water from the outside of a burning structure can quickly lower the temperatures inside. Importantly, a quick water spray from the outside doesn’t push the fire into areas that haven’t burned yet.

If you want to dive deeper into this, two great books are Fire Dynamics by Gregory Gorbett and Fireground Strategies by Anthony Avillo.

So, what exactly is a transitional fire attack? It’s a tactic where firefighters spray water from the outside to cool down the fire environment fast, before moving inside to fight the fire directly. The word “transitional” fits because it marks the change from a defensive, exterior approach to a more aggressive, interior attack.

In action, firefighters usually spray water through a window or door. This knocks down the main flames, reduces heat, and slows how fast the fire spreads making things safer for the crews who will go inside next.

Research from UL FSRI and NIST has proven that this method lowers room temperatures a lot and helps prevent flashovers. This is especially true in modern homes, where synthetic furniture causes fires to spread quickly and produce dangerous heat and smoke. Hitting the fire with water from outside before going in helps reduce the fire’s energy, giving firefighters more time and making the environment safer.

When does transitional attack make sense?

When there’s high heat and visible flames coming out of doors or windows. If the first engine crew is short-staffed.

When one or more rooms are heavily involved in fire.

If there’s a known or suspected life hazard that might benefit from quick fir. knockdown.

Some people confuse transitional attack with a fully defensive tactic or think it means giving up on rescuing people inside. That’s not true. It’s a strategic move meant to help the interior attack not replace it.

There are critics who worry that spraying water from outside might push fire into untouched areas. But studies from UL FSRI show that’s not the case. Proper exterior water application actually cools and controls the fire. On the flip side, waiting too long to apply water lets the fire grow worse, putting everyone in more danger.

But it’s not without challenges.

Transitional fire attack works well only if done right. Poor timing, lack of training, or bad communication can make things worse putting firefighters and civilians at risk. It’s crucial for incident commanders and crews to know the plan and coordinate closely.

One big risk is confusion on the fireground if the interior team doesn’t realize water will be applied from outside or thinks it means the whole operation has turned defensive.

Ventilation also has to be coordinated carefully. Opening doors or windows before water is applied can feed the fire more oxygen, making it grow faster and raising the risk of flashover. Bad timing here can undo all the benefits.

This tactic isn’t just about spraying water through a window. Firefighters need to use a straight or solid stream aimed carefully at the ceiling or upper part of the room. That cools down the hot gases and cuts thermal energy. Using the wrong nozzle or taking too long outside can delay the interior team and rescue efforts.

If there are victims in or near the fire room, spraying water from outside could slow rescue or even cause injuries from steam and heat moving around. That’s why a good size-up and careful assessment of where victims might be is key before using a transitional attack.

José Musse, Director of Fire Training Center of Peru New York City

DESASTRES.org