A320 cargo smoke / fire (alternative verification means)
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A320 cargo smoke / fire (alternative verification means)
With respect to a smoke indication and fire suppression procedures for the cargo hold of the Airbus , has anyone ever suggested ( be it Engineer or instructor or a credible book source ) to use the cargo temperature indication (if installed ) as alternative means for ongoing verification of the “status” of the cargo hold after the agent is used?
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Interesting point there C.M.
May I assume that you've probably suffered the consequences of one of these ? They're not unusual , especially if you've got a hold full of perishable goods.
I guess it's all down to co. SOP's though isn't it . And if your ECAM msg specifies certain actions , then it's a brave man who decides to rely on his knowledge , experience and common-sense in the event of a smoke warning , especially when the 20/20 hindsight club start to pick the bones out of it later.
The main consolation in all this is that most cargo hold smoke detections are spurious , but that's easy for me to say from a nice warm room.
I had a similar occurrence in Lagos a few years back : Crew got off and I was just perusing the T/L when,,ding-ding-ding-ding,,,,accompanied by ECAM msg . "Smoke Fwd Hold , Discharge Agent". When I peered out of the DV window , even in the the dark you could see the air was thick with diesel fumes from the loaders tug. Once they'd finished , the msg went .
Easy on the ground to deal with , but I think that in the air , one just has to assume a 'worst case scenario'.
Frustrating as it is...
May I assume that you've probably suffered the consequences of one of these ? They're not unusual , especially if you've got a hold full of perishable goods.
I guess it's all down to co. SOP's though isn't it . And if your ECAM msg specifies certain actions , then it's a brave man who decides to rely on his knowledge , experience and common-sense in the event of a smoke warning , especially when the 20/20 hindsight club start to pick the bones out of it later.
The main consolation in all this is that most cargo hold smoke detections are spurious , but that's easy for me to say from a nice warm room.
I had a similar occurrence in Lagos a few years back : Crew got off and I was just perusing the T/L when,,ding-ding-ding-ding,,,,accompanied by ECAM msg . "Smoke Fwd Hold , Discharge Agent". When I peered out of the DV window , even in the the dark you could see the air was thick with diesel fumes from the loaders tug. Once they'd finished , the msg went .
Easy on the ground to deal with , but I think that in the air , one just has to assume a 'worst case scenario'.
Frustrating as it is...
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Interesting point there C.M.
May I assume that you've probably suffered the consequences of one of these ? They're not unusual , especially if you've got a hold full of perishable goods.
May I assume that you've probably suffered the consequences of one of these ? They're not unusual , especially if you've got a hold full of perishable goods.
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the time a smoldering fire takes until a temperature rise is seen could be very long.
if until then you assume it's not a fire you are in for a cozy surprise.
because the fire has had time to spread and if it suddenly gets air it burned through some of the outer hull of its packaging you might be not long for this world.
the smolder could have been slowed significantly by the halon discharge but may now be too big for the halon to be effective.
So i'm quite sure because of this scenario no one could ever suggest this.
Especially with the heat loss through the hull being different depending on outside air temperature you don't know if there is fire and it's very cold out or there is no fire and it's (relatively) hot outside.
Also you would need to know how the heating system behaves: it will heat more if it it's cool and much less if there is a temperature rise but the resulting temperature might be the same or roughly the same. Thus you would need to check the heat output of the air conditioning combined with the temperature where the air leaves the compartment.
Now with modern software and a few sensors it might well be possible to calculate if there is an exothermic reaction going on in the hold but still you need to monitor a trend because freshly loaded cargo may be cot or hold so it's quite involved.
if until then you assume it's not a fire you are in for a cozy surprise.
because the fire has had time to spread and if it suddenly gets air it burned through some of the outer hull of its packaging you might be not long for this world.
the smolder could have been slowed significantly by the halon discharge but may now be too big for the halon to be effective.
So i'm quite sure because of this scenario no one could ever suggest this.
Especially with the heat loss through the hull being different depending on outside air temperature you don't know if there is fire and it's very cold out or there is no fire and it's (relatively) hot outside.
Also you would need to know how the heating system behaves: it will heat more if it it's cool and much less if there is a temperature rise but the resulting temperature might be the same or roughly the same. Thus you would need to check the heat output of the air conditioning combined with the temperature where the air leaves the compartment.
Now with modern software and a few sensors it might well be possible to calculate if there is an exothermic reaction going on in the hold but still you need to monitor a trend because freshly loaded cargo may be cot or hold so it's quite involved.
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All fire/smoke warnings are to be treated as genuine and diversion should be initiated. A fire that was noticed has become uncontrollable in eight minutes and after smoke was seen aircraft has crashed in twenty minutes. After Swiss Air111 this was the general guideline given by manufacturers.
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Ok here is the deal with the original question but before that here the concept of the cargo fire suppression
Once a fire smoke is detected inlet and outlet isolation valves close (so no air gets in and out) . With the discharging of the agent ( halon ) oxygen is “inactive” so to speak . But the assumption could be that the fire started from materials producing thermal runaway , so at some point fire could start propagating again .
I was in simulator sessions in which the suggestion was to have a cabin crew member place his/her hand on the floor at several intervals over the affected area to see if it feels warmer thus indicating deterioration after the initial discharge . Initially I didn’t think this through much , I just used it in subsequent sims . Then upon landing , if we did not have indications that fire is active , we would proceed to the parking stand escorted by the fire department , instead of emergency evacuation .
Now since there was the thought of utilizing a crew member touching the floor to establish whether or not it feels warmer ( as a basis for consider among else emergency evacuation ) , would it have been more objective to use the temperature indication as alternative means of determining fire propagation? A hand placed over a carpet which in turn is over a few layers of metal , if it feels warmer than usual it probably means that fire is really spreading around . The better indicator to this is seeing i.e an intitial 20 degree indication at some point being +40 and rising in a sealed cargo hold .
There are a different operators out there that do use the hand logic . I just hope we didn’t trap our selves into a singular technique as opposed to a better (yet not much thought of ) alternative .
Once a fire smoke is detected inlet and outlet isolation valves close (so no air gets in and out) . With the discharging of the agent ( halon ) oxygen is “inactive” so to speak . But the assumption could be that the fire started from materials producing thermal runaway , so at some point fire could start propagating again .
I was in simulator sessions in which the suggestion was to have a cabin crew member place his/her hand on the floor at several intervals over the affected area to see if it feels warmer thus indicating deterioration after the initial discharge . Initially I didn’t think this through much , I just used it in subsequent sims . Then upon landing , if we did not have indications that fire is active , we would proceed to the parking stand escorted by the fire department , instead of emergency evacuation .
Now since there was the thought of utilizing a crew member touching the floor to establish whether or not it feels warmer ( as a basis for consider among else emergency evacuation ) , would it have been more objective to use the temperature indication as alternative means of determining fire propagation? A hand placed over a carpet which in turn is over a few layers of metal , if it feels warmer than usual it probably means that fire is really spreading around . The better indicator to this is seeing i.e an intitial 20 degree indication at some point being +40 and rising in a sealed cargo hold .
There are a different operators out there that do use the hand logic . I just hope we didn’t trap our selves into a singular technique as opposed to a better (yet not much thought of ) alternative .
