Firefighting - Reconnaissance and Reading The Fire

Reconnaissance and Reading The Fire

The first step of a firefighting operation is a reconnaissance to search for the origin of the fire (which may not be obvious for an indoor fire, especially when there are no witnesses), and identification of the specific risks and any possible casualties. Any fire occurring outside may not require reconnaissance; on the other hand, a fire in a cellar or an underground car park with only a few centimeters of visibility may require a long reconnaissance to identify the seat of the fire.

The "reading" of the fire is the analysis by the firefighters of the forewarnings of a thermal accident (flashover, backdraft, smoke explosion), which is performed during the reconnaissance and the fire suppression maneuvers. The main signs are:

• Hot zones, which can be detected with a gloved hand, especially by touching a door before opening it;
• Soot on windows, which usually means that combustion is incomplete and thus there is a lack of air;
• Smoke going in and out around a door frame, as if the fire breathes, which usually means a lack of air to support combustion;
• Spraying water on the ceiling with a short pulse of a diffused spray (e.g., cone with an opening angle of 60°) to test the heat of the smoke:
  • When the temperature is moderate, the water falls down in drops with a sound of rain,
  • When the temperature is high, it vaporizes with a hiss — this can be the sign of an extremely dangerous impending flashover

Ideally, part of reconnaissance is to consult an existing preplan for the building. This provides knowledge of existing structures, firefighter hazards, and can include strategies and tactics.