Fires in underground or other hard to reach compartments often require firefighters to work against flowpaths and with limited ventilation. In these situations an interior attack may be both slow and potentially dangerous.
Cooling the fire from the exterior, either through a wall, ceiling or floor, will reduce the risk of smoke igniting. After the fuel surfaces and smoke has been cooled, ventilation may be performed if it is practical. If it is not possible to ventilate, the interior attack may be performed in a cooler and less dangerous environment.