Reading the Fire:
Air Track Indicators

In Reading the Fire: How to Improve Your Skills, I discussed building a concept map fire of behavior indicators as a method to increase competence in reading the fire. Construction of a concept map increases awareness of key indicators and understanding their interrelationships. I am working through this process along with you, with the latest revision to my concept map. Thus far, I have examined Building Factors and Smoke Indicators; the first two categories in the B-SAHF (Building, Smoke, Air Track, Heat, and Flame) organizing scheme. For review of the discussion of building factors and smoke indicators see the following Reading the Fire posts:

Focus Question

Developing a concept map starts with a focus question that specifies the problem or issue that the map is intended to help resolve. Developing or refining a concept map identifying fire behavior indicators (FBI) and their interrelationships starts with the following focus question:

What building, smoke, air track, heat, and flame indicators
provide clues to current and potential fire behavior?

As you work through this process it is likely that you will uncover additional concepts that may be added to the Building Factors or Smoke Indicators concept maps. You may also identify interrelationships that you may not have thought of previously. Don’t forget to go back and capture these thoughts as you work on the air track map.

Air Track

In Reading the Fire: Smoke Indicators, I defined the difference between Smoke and Air Track indicators. However, it may be useful to revisit the difference between these two categories before engaging in a detailed look at Air Track indicators.

Smoke: What does the smoke look like and where is it coming from? This indicator can be extremely useful in determining the location and extent of the fire. Smoke indicators may be visible on the exterior as well as inside the building. Don’t forget that size-up and dynamic risk assessment must continue after you have made entry!

Air Track: Related to smoke, air track is the movement of both smoke (generally out from the fire area) and air (generally in towards the fire area). Observation of air track starts from the exterior but becomes more critical when making entry. What does the air track look like at the door? Air track continues to be significant when you are working on the interior.

While these two sets of indicators are interrelated, they are considered separately as air track relates to movement of both smoke and air.

Getting Started

When reading the fire it is important not to focus on a single indicator or category of indicators. However, Air Track indicators often provide critical information about stages of fire development, burning regime, differences in conditions throughout the building, and direction of fire spread.

As always in developing a concept map it is important to move from general concepts to those that are more specific. Air Track must be considered at openings and inside the building. Basic indicators include direction, velocity & flow, and wind (as a major influence or modifying factor) as illustrated in Figure 1. However, you may choose to approach this somewhat differently.

Figure 1. Basic Air Track Indicators


Developing the Detail

Expanding the map requires identification of additional detail for each of the fundamental concepts. If an idea appears to be obviously related to one of the concepts already on the map, go ahead and add it. If you are unsure of where it might go, but it seems important, list it off to the side in a staging area for possible additions. Download a printer friendly version of Air Track Indicators to use as a starting point for this process.

Next Steps

Remember that the process of contracting your own map is likely as important as the (never quite) finished product. The following steps may help you expand and refine the Air Track indicators segment of the map:

  • Look at each of the subcategories individually and brainstorm additional detail. This works best if you collaborate with others.
  • Have a look at the following video clip using your partially completed map and notes as a guide to identifying important Air Track indicators. Think about what the Air Track indicators mean and visualize developing fire conditions inside the building.

The following video has some excellent Air Track indicators that may aid in developing and refining your Smoke Indicators concept map.

It may also be useful to go back and look at the video from Reading the Fire: Building Factors Part 2 or Reading the Fire: Smoke Indicators and focus in on Air Track Indicators.

Step Back and Look at the Entire Picture

Take this opportunity to engage with the rest of the B-SAHF indicators. Download and print the B-SAHF Worksheet. Consider the information provided in each of the short video clips and complete the worksheet for each. First, describe what you observe in terms of the Building, Smoke, Air Track, Heat, and Flame Indicators and then answer the following five standard questions?

  1. What additional information would you like to have? How could you obtain it?
  2. What stage(s) of development is the fire likely to be in (incipient, growth, fully developed, or decay)?
  3. What burning regime is the fire in (fuel controlled or ventilation controlled)?
  4. What conditions would you expect to find inside this building?
  5. How would you expect the fire to develop over the next two to three minutes?


While I believe that Twitter has tremendous potential for quickly sharing information and building a community of practice, the plug-in that I have been using to integrate Twitter with the CFBT-US Blog has resulted in posts being cluttered with a tremendous amount of spam. I have disabled the plug-in, but will continue to provide updates on breaking news and information via Twitter. Follow edhartin on Twitter!

Ed Hartin, MS, EFO, MIFireE, CFO

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4 Responses to “Reading the Fire:
Air Track Indicators”

  1. Stefan S Says:

    That’s a beautiful clip! My guess would be some slow burning plastic (polystyrene?), low temperature, not very dangerous at this point apart from the smoke being very thick and very black. It almost looks like an experiment. Polystyrene forms very large molecules with carbon when it burns and it requires very high temperatures to ignite. Depending on storage configuration it generally burns very slow and it could be anywhere from fuel controlled to ventilation controlled. But most likely fuel controlled at this point. I wouldn’t expect much to happen for several minutes (unless the fire service do something…).

  2. Blog Archive » Reading the FireAir Track Indicators Part 2 | Compartment Fire Behavior Says:

    […] prior post, Reading the Fire: Air Track Indicators began the process of developing or refining an existing concept map of air track indicators. It is […]

  3. Blog Archive » Reading the Fire: Flame Indicators | Compartment Fire Behavior Says:

    […] Air Track Indicators […]

  4. Blog Archive » Reading the Fire 14 | Compartment Fire Behavior Says:

    […] Reading the Fire: Air Track […]

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