Appendix 1 - Response/Intervention Time

Comprehensive Fire Safety Effectiveness Model

Appendix 1: Response/Intervention Time

All fire ground operations are time critical. The ability of a fire department to respond to every incident prior to it becoming a major conflagration is virtually impossible due to factors beyond its control. There are too many variables to accurately predict the exact response time to every incident.

It is possible, however, to project with reasonable accuracy, certain elements of the total response time equation. The following illustration depicts the variables that exist between the time a fire begins and the actual time of intervention, i.e., first application of water on the fire. Each reduction in time associated with a particular function (such as the period from dispatch until the first vehicle leaves the station) results in intervention at a lower level of the time/fire curve.

Illustration showing the relationship between property destruction/fire temperature, and the amount of time between detection and response.

Proper management of the various time elements is important, particularly during the set-up stage. It has been said that five minutes of well timed and well planned activity at this stage can avoid five hours of catch-up later.

Another time element that must be analyzed, particularly for volunteer and composite fire departments, is the time required to assemble at a fire scene. Subsequently the time taken by the crew to complete each evolution required to initiate interior fire suppression will have a significant impact on the capacity of the department to extinguish the fire effectively.

Fire departments have used two different methods of calculating response time. Many departments have adopted the OFM method which, for the purposes of statistical reporting, is defined as follows: "The elapsed time between receipt of the call by the department and the arrival of the first unit at the occurrence location." Other departments have adopted "response travel time" which is considered to be the time from when the vehicles leave the station until arrival at the occurrence location. Therefore those departments which have adopted the OFM definition will have greater average response time results than those adopting response travel time.

Regardless of which definition is adopted, fire department response time is a function of various factors including, but not limited to:

  • the distance between the fire department and response location
  • the layout of the community
  • impediments such as weather, construction, traffic jams, lack of roads
  • notification time
  • assembly time