Single Pack Ops A320
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Single Pack Ops A320
A320/321
Problem:
Dispatch with One Pack u/s - Some sections of the MEL specify limit of FL325 and some sections DO NOT specify an Altitude limit.
Why and what is the logic behind this?
ANOTHER un-related problem:
Dispatch with ALL systems on plane working:
flying along in cruise at FL380 and one pack fault, and cannot be recovered, pressurisation is holding, any regulation, limitation that neccesitates a decent to a lower level?
thanks
Problem:
Dispatch with One Pack u/s - Some sections of the MEL specify limit of FL325 and some sections DO NOT specify an Altitude limit.
Why and what is the logic behind this?
ANOTHER un-related problem:
Dispatch with ALL systems on plane working:
flying along in cruise at FL380 and one pack fault, and cannot be recovered, pressurisation is holding, any regulation, limitation that neccesitates a decent to a lower level?
thanks
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hi
The only consideration that i am aware of is for flight spoilers...if they are operative and pressurization is holding, then it should be ok
If on the other hand the aircraft is dispatched with them inop..the aircraft in our manuals is limited to F315..tht is the level you can desend from without flight spoilers to F100 within the time frame for oxygen available in the event where you loose the other pack and aircraft pressurization is completely lost
The only consideration that i am aware of is for flight spoilers...if they are operative and pressurization is holding, then it should be ok
If on the other hand the aircraft is dispatched with them inop..the aircraft in our manuals is limited to F315..tht is the level you can desend from without flight spoilers to F100 within the time frame for oxygen available in the event where you loose the other pack and aircraft pressurization is completely lost
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A colleague of mine asked the same question to Airbus
When an aircraft is dispatched with one pack inoperative, Airbus takes into account a failure in flight of the remaining pack and a descent to FL100.
The FL limitation provided in the MMEL ensures that:
The cabin altitude will never be above 15,000 ft during the descent, and
The oxygen masks will not drop during the descent.
Hence the FL limit.
Hope this helps
When an aircraft is dispatched with one pack inoperative, Airbus takes into account a failure in flight of the remaining pack and a descent to FL100.
The FL limitation provided in the MMEL ensures that:
The cabin altitude will never be above 15,000 ft during the descent, and
The oxygen masks will not drop during the descent.
Hence the FL limit.
Hope this helps
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Yes, FL315, I stand corrected. Thanks!
What about losing a pack while cruising at FL390, pressurisation is holding normal, any documentation from airbus that warrants a decend to FL315 and below?
Many thanks to fellow bus drivers around the globe
What about losing a pack while cruising at FL390, pressurisation is holding normal, any documentation from airbus that warrants a decend to FL315 and below?
Many thanks to fellow bus drivers around the globe
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Surely not. If the pack fails in flight, run the ECAM procedure; the MEL limitations discussed above do not apply since the aircraft is already in flight.
Cheers
mcdhu
Cheers
mcdhu
Moderator
Important to keep in mind what the MEL is all about .. and that is to permit the intentional despatch with bits and pieces U/S.
It is the intentional aspect that drives the philosophy. With intent it is appropriate to address the basic certification requirements .. eg, for packs, why did we have two for the original certification ? If we launch with one U/S, then what do we need to do in the way of restriction to achieve a similar risk environment to normal operations ? and the M(M)EL words follow on from the answer to that question.
the MEL limitations discussed above do not apply since the aircraft is already in flight.
That's fine .. but it is a wise pilot who reviews the MEL after the situation has settled down .. the words provide a few more bits of the puzzle for his/her flight conduct decision processes.
It is the intentional aspect that drives the philosophy. With intent it is appropriate to address the basic certification requirements .. eg, for packs, why did we have two for the original certification ? If we launch with one U/S, then what do we need to do in the way of restriction to achieve a similar risk environment to normal operations ? and the M(M)EL words follow on from the answer to that question.
the MEL limitations discussed above do not apply since the aircraft is already in flight.
That's fine .. but it is a wise pilot who reviews the MEL after the situation has settled down .. the words provide a few more bits of the puzzle for his/her flight conduct decision processes.
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So what you are saying is that it is Prudent and Good airmanship/common sense to CONSIDER a descend to a lower level after one pack fault in cruise at lets say FL390 even if the pressurasation is holding.
It is not a requirement nor a limit as airplane is already inflight, correct?
It is not a requirement nor a limit as airplane is already inflight, correct?
Moderator
That's the way I would look at it ... do I have adequate fuel to tolerate continuing at a lower level ? If so, I would weigh up the fuel cost against the (probably low) risk of having a serious depressurisation at normal cruise level in the event that the other pack lets go ...
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You guys are not making much sense!
If you have and explosive decompression, no matter how many packs you have operating; you can get down from 390 within the oxygen generator time, whatever the option of minutes your airline chose.
The MEL limitation is ONLY for dispatch, it does NOT apply in flight. The reason it is limited by MEL is the ability to pressurize the A/C in climb and just a preventive measure at that. If you are at FL390 and turn off a pack, nothing happens; if you turn off both pack you would get a cabin altitude rate of climb of about 650 to 800 FPM; I have seen it even on 10 and 12 year old A320's. If at that time you make a good decision and a timely EMERG DESCENT, most likely you will get to 14,000 (or 16,000 with HIGH ALT PB) before even the masks drop.
DTG: Your colleague is either making it up or asked the wrong department at Airbus, and BTW masks drop normally at 14,000 not 15,000 unless you have selected the optional HIGH ALT PB then they drop at 16,000. If he is with an Airbus operator in management, tell him to pm me and I'll give him the Dept where he should send this questions.
G
If you have and explosive decompression, no matter how many packs you have operating; you can get down from 390 within the oxygen generator time, whatever the option of minutes your airline chose.
The MEL limitation is ONLY for dispatch, it does NOT apply in flight. The reason it is limited by MEL is the ability to pressurize the A/C in climb and just a preventive measure at that. If you are at FL390 and turn off a pack, nothing happens; if you turn off both pack you would get a cabin altitude rate of climb of about 650 to 800 FPM; I have seen it even on 10 and 12 year old A320's. If at that time you make a good decision and a timely EMERG DESCENT, most likely you will get to 14,000 (or 16,000 with HIGH ALT PB) before even the masks drop.
DTG: Your colleague is either making it up or asked the wrong department at Airbus, and BTW masks drop normally at 14,000 not 15,000 unless you have selected the optional HIGH ALT PB then they drop at 16,000. If he is with an Airbus operator in management, tell him to pm me and I'll give him the Dept where he should send this questions.
G
Last edited by guiones; 15th Mar 2009 at 04:41.
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I would have thought that JT's post no 10 above makes absolute sense.
The final part of any decision making model GRADE, DODAR etc is to continuously review/evaluate the outcome which includes asking the question ''what if the next one fails?''.
True, an (emergency) descent from FL390 should sort it out but it will probably be ugly; an emergency descent from FL 310 will be less so.
But there are many more factors to consider - but at least we should consider them.
Must go flying
Cheers all,
mcdhu
The final part of any decision making model GRADE, DODAR etc is to continuously review/evaluate the outcome which includes asking the question ''what if the next one fails?''.
True, an (emergency) descent from FL390 should sort it out but it will probably be ugly; an emergency descent from FL 310 will be less so.
But there are many more factors to consider - but at least we should consider them.
Must go flying
Cheers all,
mcdhu
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YankeeGolf
With regard to your question about whether you should descend from FL390 with a pack that's failed while you were up there.
My answer would be no. AS LONG AS pressurisation holds.
Think of a aircraft like a leaky balloon. It takes a lot of puffing to inflate it, but once the balloon is filled it takes a lot less puffing to keep it inflated.
With regard to your question about whether you should descend from FL390 with a pack that's failed while you were up there.
My answer would be no. AS LONG AS pressurisation holds.
Think of a aircraft like a leaky balloon. It takes a lot of puffing to inflate it, but once the balloon is filled it takes a lot less puffing to keep it inflated.
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YG:
If you have a Technical Management position for an Airbus Operator, you should have access to the Airbus World site; thats the best way to go. There are also adresses directly to the technical deptarments in Toulouse for every system, this is also only for Airlines that operate Airbus; certainly not for curious people on a forum. If you have any questions, feel free to pm me.
mcdhu:
An EMERG DESC from 390 and 310 should be exacly the same, the ONLY difference should be about 2 minutes to get to the desired altitude, noting ugly. Worst case scenario is that the the mask will drop, nothing else.
G
If you have a Technical Management position for an Airbus Operator, you should have access to the Airbus World site; thats the best way to go. There are also adresses directly to the technical deptarments in Toulouse for every system, this is also only for Airlines that operate Airbus; certainly not for curious people on a forum. If you have any questions, feel free to pm me.
mcdhu:
An EMERG DESC from 390 and 310 should be exacly the same, the ONLY difference should be about 2 minutes to get to the desired altitude, noting ugly. Worst case scenario is that the the mask will drop, nothing else.
G
Moderator
Worst case scenario is that the the mask will drop, nothing else.
I would also suggest consideration of what-ifs and how high the cabin might peak during any descent .. considering that we are looking at typical populations in the cabin and all the potential medical complications which might attend a cabin pressure excursion ?
If you don't have a reasonable option and need to stay high .. fine. If you have options, then consider what your responses might be during court time when you are called to account for your decision making processes by counsel for a passenger who suffers injury and then sues ...
I would also suggest consideration of what-ifs and how high the cabin might peak during any descent .. considering that we are looking at typical populations in the cabin and all the potential medical complications which might attend a cabin pressure excursion ?
If you don't have a reasonable option and need to stay high .. fine. If you have options, then consider what your responses might be during court time when you are called to account for your decision making processes by counsel for a passenger who suffers injury and then sues ...
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JT:
We are talking Airbus procedures not lawyers. If every time you fly you are worried about lawyers, stay home.
The chance of a dual pack failure is rare, and Airbus sees it that way.
Would be intresting what other procedures or recomendations from the manufacturer you do not follow to please lawyers.
My answer is: I followed manufacturer procedure and recomendations.
If the passengers can't handle a dual pack failure, imagine what an explosive decompression would do to them. If you read my previous post, the A320 series with both paks off get a cabin rate of climb of about 650 to 800 FPM, hardly dramatic.
G
We are talking Airbus procedures not lawyers. If every time you fly you are worried about lawyers, stay home.
The chance of a dual pack failure is rare, and Airbus sees it that way.
Would be intresting what other procedures or recomendations from the manufacturer you do not follow to please lawyers.
My answer is: I followed manufacturer procedure and recomendations.
If the passengers can't handle a dual pack failure, imagine what an explosive decompression would do to them. If you read my previous post, the A320 series with both paks off get a cabin rate of climb of about 650 to 800 FPM, hardly dramatic.
G
Last edited by guiones; 16th Mar 2009 at 05:27.
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Normally I would not respond but the liability topic is relevant and very important .. not to mention very poorly considered and understood by the average professional going about his business ...
We are talking Airbus procedure not lawyers.
At the enquiry, we ARE talking lawyers. Every time you make a decision, give advice, etc., as a competent professional .. your call can be brought to account in court.
If every time you fly you are worried about lawyers, stay home.
Not only every time I might fly .. but every time I put my engineering or management hat on as well. This is the reality of the modern world, liability, and responsibility. Not so much a case of being worried as being aware and prudent.
The chance of a dual pack failure is rare, and Airbus sees it that way.
Of course a dual failure is not an everyday event - I think we all accept that .... but your view is that the Commander ought not consider the circumstances of the particular flight and merely follow the QRH or equivalent in the nature of an automaton ?
My answer is: I followed manufacturer procedure and recomendations.
.. and that will provide you with some protection. However, I think that you need to read some court/BOI/etc. transcripts .. might cause you to raise your eyebrows a little, I suspect. Your view is idealistic but, in practice, not the way the real world works after the event ..
We are talking Airbus procedure not lawyers.
At the enquiry, we ARE talking lawyers. Every time you make a decision, give advice, etc., as a competent professional .. your call can be brought to account in court.
If every time you fly you are worried about lawyers, stay home.
Not only every time I might fly .. but every time I put my engineering or management hat on as well. This is the reality of the modern world, liability, and responsibility. Not so much a case of being worried as being aware and prudent.
The chance of a dual pack failure is rare, and Airbus sees it that way.
Of course a dual failure is not an everyday event - I think we all accept that .... but your view is that the Commander ought not consider the circumstances of the particular flight and merely follow the QRH or equivalent in the nature of an automaton ?
My answer is: I followed manufacturer procedure and recomendations.
.. and that will provide you with some protection. However, I think that you need to read some court/BOI/etc. transcripts .. might cause you to raise your eyebrows a little, I suspect. Your view is idealistic but, in practice, not the way the real world works after the event ..
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JT
I do not let lawyers or enquirys dictate the way I operate an airplane; I do that better than them.
I follow procedures and recomendations developed by the manufacturer after extensive testing and with the knowlege of the people that developed the systems. If there is a procedure I do not agree with, I ask Airbus.
You are putting words in my mouth by saying "but your view is that the Commander ought not consider the circumstances of the particular flight and merely follow the QRH or equivalent in the nature of an automaton?"
The PIC has the ultimate authority of decision making; never sugested to take that away; but procedures were developed with more knowlege than you, I or any single person might have, I follow them. The A320 series is complex enough to start second guessing the way it is recomended by Airbus that we fly it.
Where do you stop with your thinking, what other recomendations do you change, what other areas and what parameters do you allow yourself to protect yourself from liability? The lawyers will always find a way to find you at fault; example: "why did you descent when the experts at the manufacturer and you documents onboard say you do not need to, maybe if you stayed at 390 like Airbus recomended you would have stayed out of the clear air turbulence that hurt your typical 90 year old great grandma that was walking with her cane to the restroom? Do you think you know better than the experts at Airbus?"
We can not let aviation ignorant lawyers dictate the way we operate the A/C; that is what make us different.
And BTW, I don't need to read about lawyers and accidents or incidents; I have testified about procedures at several and have been involved in many accident investigations(currently involved in one). One of the big reasons I take what Airbus writes very seriously.
Happy landings.
G
I do not let lawyers or enquirys dictate the way I operate an airplane; I do that better than them.
I follow procedures and recomendations developed by the manufacturer after extensive testing and with the knowlege of the people that developed the systems. If there is a procedure I do not agree with, I ask Airbus.
You are putting words in my mouth by saying "but your view is that the Commander ought not consider the circumstances of the particular flight and merely follow the QRH or equivalent in the nature of an automaton?"
The PIC has the ultimate authority of decision making; never sugested to take that away; but procedures were developed with more knowlege than you, I or any single person might have, I follow them. The A320 series is complex enough to start second guessing the way it is recomended by Airbus that we fly it.
Where do you stop with your thinking, what other recomendations do you change, what other areas and what parameters do you allow yourself to protect yourself from liability? The lawyers will always find a way to find you at fault; example: "why did you descent when the experts at the manufacturer and you documents onboard say you do not need to, maybe if you stayed at 390 like Airbus recomended you would have stayed out of the clear air turbulence that hurt your typical 90 year old great grandma that was walking with her cane to the restroom? Do you think you know better than the experts at Airbus?"
We can not let aviation ignorant lawyers dictate the way we operate the A/C; that is what make us different.
And BTW, I don't need to read about lawyers and accidents or incidents; I have testified about procedures at several and have been involved in many accident investigations(currently involved in one). One of the big reasons I take what Airbus writes very seriously.
Happy landings.
G
