By Michael S. Terwilliger
Wildfires have been with us since the beginning of time, but we have been involved in the formal process of dealing with them only recently, perhaps for the last 100 years give or take. The fires have not really changed much, and neither have we with a few exceptions. One thing has not changed is firefighters deciding when it is time to disengage. When I joined the fire service in 1972, we did not have a fancy terms like disengagement. Back then, disengagement was more a learned behavior sometimes called “get on old paint and ride where you ain’t.” Either way, we were doing something then and it is worth looking at in a formal manner now.
1972 was a simpler time so to speak. The Forest Fire Fighting Fundamentals was a small booklet that taught us about wildfire and safety using rhymes. It worked–I still remember some. For example: “check your exit well and often, you’re too young to fill a coffin” is still with me to this day. This rhyme was telling us to make sure we always had an escape route. Years ago an incident commander may have said, “lets get out of here,” while today’s IC, might say, “it is time to disengage.” Both are saying the same thing but the decision tree is a little more formalized. The response from the firefighters then and now has either been, “how come,” or “it is about time.” Those responses are why disengagement must be the result of established criteria.
Preplan
When firefighters are preparing to go out on the line, they need to know what the disengagement criteria is going to be and that disengagement is an acceptable procedure. Some conditions that may require some type of disengagement include: lowering relative humidity, increasing air temperature, changing winds, topographical influences, increased time/distance to safety zones, loss of support, fatigue, loss of lookouts, loss of communication, and mission failure. Though not complete, this list suggests criteria of which all crewmembers should be aware when fighting fire. If disengagement criteria are discussed prior to the incident, you will achieve two important things:
- All crew members will be empowered to watch out for the entire crew.
- When it is time to disengage the entire crew will know why.
An example of using weather benchmarks for disengagement criteria occurred in the Rocky Mountains in 1988. Every afternoon when the humidity reached 12 percent, the wind reached 15 MPH, and the air temperature was above 80 degrees, the fire would get into the crowns of the Lodgepole Pine and make sustained crown runs. Firefighting tactics employed here were no longer effective and it was not safe to stand around and watch. Firefighters used the numbers listed above as disengagement criteria until the condition of the fuels changed drastically with seasonal influences.
Disengagement Types
When a benchmark is established for disengagement, you also have to determine what type of disengagement you will employ if conditions reach the benchmark. When you reach your predetermined disengagement benchmarks, use the following to determine what action will be taken:
- Hold in Place: Stay where you are located because it is safe. You might do so until more or different resources arrive that can deal with the new intensities. Perhaps a water-dropping helicopter can cool the fire ahead of you allowing the continuation of line construction.
- Change Tactics: You might have been involved in direct attack at the fire edge. The new intensities preclude being so close so you back off some and use indirect tactics such as line construction and burning out.
- Pull Back: Take your personnel to an agreed upon location until the fire is safe to deal with. The intent is to minimize the time and distance to safety zones. This would be done with the anticipation that something will be changing in your favor so some form of attack will continue when appropriate.
- Retreat: stop all operations and move to a safety zone with the understanding that the strategy and ensuing tactics will not be applicable for the remainder of the operational period and staying in the area will compromise your escape route or safety.
Of the four types of disengagement listed above, three consider continuance of operations in some form. In these cases, establish the criteria used to determine when it is okay to return to work. This should be an organized sequence of events, and described within the four types of disengagement. Of equal importance is an understanding that all parts of a wildfire strategy and tactics are linked in some fashion. We are NEVER compartmentalized while on the line, and all of our actions need to be shared with all partners on the fire or at best those adjacent to us. Therefore, the final component is communication of the plan, communication of the implementation of the plan, what type of implementation, and finally what the final result will be. An example of disengagement might sound like this:
“Operations, Division A.”“Go ahead Division A.”
“Operations, the personnel on Division A are going to disengage and pull back to the Smith Creek safety zone. The fire is making a sustained run on the division and we need to rethink the tactics being deployed. I would like to have a face to face with you at that location in 20 minutes.”
“Division A, Operations that is affirmative, please advise me when all of your assets are at the safety zone.”
Remember that disengagement is a fancy word describing what we have always done at some time at a fire. Don’t get caught up with terms or new ways of describing situations. If you prefer to call it “getting on old paint and riding where you ain’t,” that’s fine. Just make this promise to your firefighters now: when fighting a fire as I have described above make sure your crew knows in advance when it will be time to get on old paint, where old paint will be located, and if they miss the ride, where old paint is headed. Choosing to have no plan is a plan in itself–it’s just that it’s a bad one. Be safe.
Michael S. Terwilliger is chief of the Truckee (CA) Fire Protection District. He began his career in 1972 with the California Department of Forestry, where he served for 24 years in the following assignments: division chief of operations (South) in the Nevada-Yuba-Placer Ranger Unit and as operation section chief and planning section chief on a Type I team from 1988 to 1996. He is a certified fire behavior analyst. Terwilliger is incident commander for Sierra Front Wildfire Cooperators Team, which operates along the eastern California/Nevada border. He also instructs operations section chiefs, division group supervisors, and strike team leaders.
