The transitional fire attack is a relatively new tactic by name, but some of its practices have been around for many years. This tactic gained traction in the last two years as a result of the studies completed by the National Institute of Standards and Technology (NIST) and Underwriters’ Laboratories (UL) in New York and Chicago.
By Mark van
The studies were conducted to show the science behind modern-day fires and the need to adapt tactics.
Life safety or rescue is still the No. 1 priority. The transitional fire attack does not remove this fire-ground priority and actually allows for rescues to be made with intensive fire or heat showing in or nearby the location of the occupants.
Many people in the fire service who read the data and the report from the UL/NIST study come away with misunderstandings: the belief that a transitional fire attack is a replacement for the interior attack; and the assumption that incorporating the tactic requires a fire department to become a defensive operational unit only. In fact, the opposite is true. The transitional fire attack is a supplement to the interior attack and by incorporating the tactic, a fire department can be both defensive and offensive.
Why use the transitional fire attack? Is it because fires are hotter than they were 20 years ago? The answer is no – fires are not hotter today than they were 20 years ago. A fire’s heat-release rate is what has changed. Fires today release energy and reach extreme temperatures much more quickly than before due to the petro-chemicals used to produce everyday products and furnishings. These chemicals burn with higher and faster heat release rates (HRR).
When determining litres per minute or gallons per minute of water needed at the scene, firefighters should be looking at HRR and not British Thermal Units (BTUs). BTU is a measurement of temperature and not the release of heat. To fight fires, crews require enough water to overcome the HRR that is present rather than the temperature within that compartment. A transitional fire attack is one of the ways firefighters can overcome the quick and high buildup of the HRR.
The transitional fire attack works best when crews observe a self-venting fire from a window, and have the report of occupants still inside or instructions to conduct a primary search as well as suppress the fire. The key factor for this tactic to work is the size-up or 360-degree walk around. It is imperative that the first-arriving officer with the first-arriving unit complete a walk around to size-up the fire and the building.
During the size-up, the officer must determine if the fire vent is limited (contained to the interior) or self-venting. In photo 2, the fire is self-venting – it is not contained to the interior. This situation would allow for a transitional fire attack.
Once the decision is made, the attack line is pulled off, flaked out, charged and then readied for water application from the outside. A firefighter aims the nozzle – on a straight-stream pattern or with a smooth-bore nozzle – to create a stream of water directly up to the ceiling of the room so as to create a sprinkler-head discharge within that room (see photo 1).
Aim the stream of water at the ceiling directly above the fire, and maintain a static motion for about 10 seconds. The stream of water should not move in a circular fashion or up and down as firefighters naturally want to do – it has to stay static, similar to a sprinkler head. Creating a narrow, static stream avoids blocking the vent opening of the window to allow the steam and hot gases to flow out. The attack maintains the bi-directional flow path already established at that window so that it works for the firefighters and not against them.
Once water is applied for about 10 seconds, firefighters then make their way into the building to aggressively suppress the fire from inside and perform any necessary rescues.
The UL/NIST studies show that the temperature reductions gained by the transitional attack are significant – so much so that occupants near the fire room, in the hallway, in other rooms, or on another floor are going to experience a temperature drop of about 50 per cent or more than they would had a traditional attack method been used. Temperature reductions increase the odds of occupant survival and also ease the path for firefighters to enter with the attack line to suppress the remaining fire.
There are two ways to approach this tactic – use the same hoseline for the exterior water application and interior attack, or use two separate hoselines, one for the exterior water application and the other for the interior attack. Depending on the size of the building and the location of the fire, using two lines may cut down the time it takes to move the line from the outside to the inside.
The transitional-attack tactic works only when it has been practised on the training ground; it is not to be used for the first time during a real call.
Mark van der Feyst has been in the fire service since 1999 and is a full-time firefighter in Ontario. Mark teaches in Canada, the United States and India. He is also the lead author of Residential Fire Rescue. Email Mark at Mark@FireStarTraining.com