Having flown SLF for some time I am not used to the idea of cargo compartments without fire suppression.
I see this topic very simplistically.
Fire, once started and if not controlled or contained will develop with a mind of its own and exponentially grow consuming all that is around it.
Survival:
1) Escape from the fire, via fire exits... (Not viable in flight on civil aircraft)
2) Extinguish the fire... (Definately my preference!)
I have heard arguments that suggest some fires are inextinguishable!
I have two points to make;
Firstly, inextinguishable fires are usually as a result of not being detected and controlled early enough. This is always the case with aircraft that have managed to land after detecting fire but not suppressing it.
Otherwise, we could have materials onboard that do not respond to the suppressant installed. In reality this is mainly class D fires (metals). A top contender being lithium batteries, because nearly all other metal sources would need to be heated externally first. Now while our Halon 1301 will not stop the heat rising within lithium batteries it will interfere with the chemical process that allows flame to persist and more imortantly spread!
This is why we call it suppressant and not extinguisher!
Suppress the fire = time
Time is my friend when my arse is on fire and I want to find somewhere to land.
I would definately like to see more time invested in finding suitable ways of installing suppressant in main deck cargo holds. Frankly, any company operating the average aircraft without suppressant in the lower holds, is just asking for trouble. These areas are easily classified as Class C compartments, because of the ability to regulate the airflow to them. Boeing have kits for all their variants, which add minimal weight and take up zero space within these holds!
boeing fire suppression upgrades
For a typical ETOPS (ie 180mins of suppression) kit you would lose only 65kg of useable payload!
I understand that if the refit is included within a C check it is as good as cost neutral!