An underestimated element in the scope of Crans-Montana tragedythe Swiss town where a restaurant caught fire on New Year’s Eve, killing 47 people and injuring 115, is the fact that the flames spread not on the ground, but on the ceiling. At first glance, it might seem that if the ceiling catches fire, people would be safer and have more time to evacuate the room, but in reality fires that hit a ceiling can be even more dangerous: at least in the context of the basement bar room The Constellationsthe presence of flames above people’s heads worsened an already dramatic situation.
According to initial reconstructions, the one that burned first was the soundproofing panel applied to the ceiling of the room. While in a “normal” fire (where something on the floor or in any case in the lower part of the room catches fire) the heat and combustion products spread mainly upwards given their low density, if the ceiling catches fire the tendency of the flames to rise leads them to expand horizontallyespecially if the material that is on fire is highly flammable like the foam of a soundproofing panel. So here we have a fire with a important horizontal development and temperatures around 1000°C.
While on the one hand this helps contain the extreme heat in the upper part of the room, on the other hand for those inside it it essentially meant having a “wall of fire” above their heads. Wall of fire that emits a large amount of thermal radiation downwards (i.e. towards the people themselves) and which causes the detachment and fall of glowing foamwith temperatures that burn the skin and carry the fire even to the floor of the room.
To this must be added the fact that the flames, in their tendency to rise, have found how natural route of propagation is the staircase which led to the upper floor and which for the occupants of the room represented theonly escape route. At this point we had dozens of completely panicked people crowded into a narrow, uphill corridor, engulfed in flames and filled with toxic fumes. This contributed to the fact that so few of those in the basement of the venue managed to escape the tragedy.
