Airbus 380 loses engine, goes 5000 miles
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Just SLF and trust the right decision was made in this situation
One thing I note is that in the discussions above that some do not understand conditional statistics. I suggest some posters read up on it.
Next, derived from this, a question: Is a 747 / 380 on two engines after a random initial failure and no diversion followed by a second random failure just as flyable, stable and 'safe' as a 777 on one engine (assuming for both no more engine failures) ? If not, then a drop from 3 to 2 on a 747 / 380 is more 'seious' than a drop from 2 to 1 on a 777.
Yet another question: To what extent is it possible to know fully and completely the cause of an engine failure before a mechanic opens up the engine?
If it is 100% possible in some situations, then in those situations the chance of a second failure is equal to the chance of the initial random failure.
If it is not possible to know 100%, then there must be assumed a greater risk of a second or further failure.
I know stats, but not piloting, so I do not have the full answers to these questions, but they are central to situations such as this.
One thing I note is that in the discussions above that some do not understand conditional statistics. I suggest some posters read up on it.
Next, derived from this, a question: Is a 747 / 380 on two engines after a random initial failure and no diversion followed by a second random failure just as flyable, stable and 'safe' as a 777 on one engine (assuming for both no more engine failures) ? If not, then a drop from 3 to 2 on a 747 / 380 is more 'seious' than a drop from 2 to 1 on a 777.
Yet another question: To what extent is it possible to know fully and completely the cause of an engine failure before a mechanic opens up the engine?
If it is 100% possible in some situations, then in those situations the chance of a second failure is equal to the chance of the initial random failure.
If it is not possible to know 100%, then there must be assumed a greater risk of a second or further failure.
I know stats, but not piloting, so I do not have the full answers to these questions, but they are central to situations such as this.
Do a Hover - it avoids G
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Some may think this relevant to this thread, others may not.
Jet engines typically need a pump for them to run in a high altitude cruise.
Providing there is gravity feed (fuel tank above engine) the engine will run at low level without a pump.
The max altitude for running without a pump is type dependant.
So unless you want to land at a very high level please be assured you can relight a donk as you saunter into land if that donk has flamed out at height because it has no pump.
Jet engines typically need a pump for them to run in a high altitude cruise.
Providing there is gravity feed (fuel tank above engine) the engine will run at low level without a pump.
The max altitude for running without a pump is type dependant.
So unless you want to land at a very high level please be assured you can relight a donk as you saunter into land if that donk has flamed out at height because it has no pump.
Teachme
Ref. the above - is it valid to discuss/compare an aircraft which has had TWO separate failures with an aircraft that's just had ONE ? Should we not discuss the 747 / 380 with two engine failures compared to a 777 with two engine failures ..... using your criteria of "random failure" - Apples to apples and all that !
..... I guess we can talk about the probability of a 747 losing two and the probability of a 777 losing two (I'm told it's the same) but moving to the real world .... what is the effect ? Bearing in mind we have been unable to think of an incident/accident where a four engine jet aircraft "continuing" on three after a "random failure" has had a problem - it's been going on since the mid fifties !
Next, derived from this, a question: Is a 747 / 380 on two engines after a random initial failure and no diversion followed by a second random failure just as flyable, stable and 'safe' as a 777 on one engine (assuming for both no more engine failures)
..... I guess we can talk about the probability of a 747 losing two and the probability of a 777 losing two (I'm told it's the same) but moving to the real world .... what is the effect ? Bearing in mind we have been unable to think of an incident/accident where a four engine jet aircraft "continuing" on three after a "random failure" has had a problem - it's been going on since the mid fifties !
Last edited by Good Business Sense; 16th Nov 2013 at 17:00.
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Possibly germane to this discussion: National Airlines Flight 27 - Wikipedia, the free encyclopedia
(DC-10) When #3 fan disintegrated, one fan blade was thrown into the accessory gearbox of #1 engine, stopping its fuel pump so it immediately flamed out. #2 also received FOD but continued to run. The aircraft landed successfully at ABQ.
(DC-10) When #3 fan disintegrated, one fan blade was thrown into the accessory gearbox of #1 engine, stopping its fuel pump so it immediately flamed out. #2 also received FOD but continued to run. The aircraft landed successfully at ABQ.
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This is what I was told when I was in school
Lets say engine reliability = 0.99
2 engine: 0.99^2 = 0.9801
4 engine: 0.99^4 = 0.9605
i.e. 4 engine is less reliable in engine terms than a 2 engine. Thats how it has been since forever. What changed over time is engine reliability, thus what failure mode is more important (engine failure itself or outcome of engine failure)
An engine failure can be anything. Fuel pump or turbine disk failure (uncontained)
A fuel pump failure is unlikely to create further problems. A turbine disk failure may create more problems. But both are engine failures. See recent A380 or old times DC-10 ( the one that burst the hydraulic lines).
Back in the days that engines were less reliable, more engines were a short of 'redundancy' because they were unreliable (compared to nowadays).
Now that engine reliability is higher, probability of losing engine is low, thus you don't need many engines cause even if you lose one (extremely unlikely event), its extremely unlikely that you loose one again (due to engine reliability).
Problem arises by the likelihood of damage to other systems due to engine failure (for example turbine disk failure). In that respect a 4 engine plane is more likely to get damaged due to one of its engines failing, because it has more engines. Furthermore engine failure of any short is distracting to the crew, ATC etc etc, i.e. other things can go wrong and line up the holes.
So nowdays with extremely reliable engines, there is less benefit from engine redundancy (3-4 instead of 2) because adding more engines reduces the reliability of the overall system (plane). That doesn't mean that its not safe to have more engines, it means that there is a trade off between 'how many engines' and 'what do I have to gain'. Back in the days you gained redundancy, nowadays you gain other things. The only sure thing is that engines are more reliable and that makes aviation safer and planes better.
If the fuel is contaminated, or if the same person installed all fuel pumps wrong in all engines is a different story and there are other safeguards against that. If the same person installs and checks all the fuel pumps on a 2 or a 4 or a 256 engine plane, then all engine reliability figures fly off the window because chance of engine failure is not based on independent probabilities anymore.
btw, I'm not saying that the number of engines during design depends only on the above. The above are the reasons that ETOPS became possible.
2 engine: 0.99^2 = 0.9801
4 engine: 0.99^4 = 0.9605
i.e. 4 engine is less reliable in engine terms than a 2 engine. Thats how it has been since forever. What changed over time is engine reliability, thus what failure mode is more important (engine failure itself or outcome of engine failure)
An engine failure can be anything. Fuel pump or turbine disk failure (uncontained)
A fuel pump failure is unlikely to create further problems. A turbine disk failure may create more problems. But both are engine failures. See recent A380 or old times DC-10 ( the one that burst the hydraulic lines).
Back in the days that engines were less reliable, more engines were a short of 'redundancy' because they were unreliable (compared to nowadays).
Now that engine reliability is higher, probability of losing engine is low, thus you don't need many engines cause even if you lose one (extremely unlikely event), its extremely unlikely that you loose one again (due to engine reliability).
Problem arises by the likelihood of damage to other systems due to engine failure (for example turbine disk failure). In that respect a 4 engine plane is more likely to get damaged due to one of its engines failing, because it has more engines. Furthermore engine failure of any short is distracting to the crew, ATC etc etc, i.e. other things can go wrong and line up the holes.
So nowdays with extremely reliable engines, there is less benefit from engine redundancy (3-4 instead of 2) because adding more engines reduces the reliability of the overall system (plane). That doesn't mean that its not safe to have more engines, it means that there is a trade off between 'how many engines' and 'what do I have to gain'. Back in the days you gained redundancy, nowadays you gain other things. The only sure thing is that engines are more reliable and that makes aviation safer and planes better.
If the fuel is contaminated, or if the same person installed all fuel pumps wrong in all engines is a different story and there are other safeguards against that. If the same person installs and checks all the fuel pumps on a 2 or a 4 or a 256 engine plane, then all engine reliability figures fly off the window because chance of engine failure is not based on independent probabilities anymore.
btw, I'm not saying that the number of engines during design depends only on the above. The above are the reasons that ETOPS became possible.
Possibly germane to this discussion
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Statistics Eh?
Mr Sober Lark
With regards to my statment about the Next engine failing after the first,within 5 min to 5 hrs,in one of 5000 cases ,I forgot about the Dc 10 and the Fokker 70 ( klm Torino to) sas dc9 etc.
My middel name is M for Murphy, ic the Devils advocaat, to many students has said, Noway!?.....You are full of it,
They are right , I am , full of old stories that will repeat themself.
Historic fact, :if one engine fails ,the next Statisticaly will fail inside 5 hrs.the next 5000 hrs . Not in 10 million hrs.
With regards to the case and BA they monitored the rest of the engines and the maint. Records and could provide the Commander with confirmation that he was safer then a Etops twin to go to destination.
With regards to my statment about the Next engine failing after the first,within 5 min to 5 hrs,in one of 5000 cases ,I forgot about the Dc 10 and the Fokker 70 ( klm Torino to) sas dc9 etc.
My middel name is M for Murphy, ic the Devils advocaat, to many students has said, Noway!?.....You are full of it,
They are right , I am , full of old stories that will repeat themself.
Historic fact, :if one engine fails ,the next Statisticaly will fail inside 5 hrs.the next 5000 hrs . Not in 10 million hrs.
With regards to the case and BA they monitored the rest of the engines and the maint. Records and could provide the Commander with confirmation that he was safer then a Etops twin to go to destination.
barit1
Was the National incident the one where the F/E was suspected of inducing a failure of the engine speed controls? Not a "normal" failure, if so.
Was the National incident the one where the F/E was suspected of inducing a failure of the engine speed controls? Not a "normal" failure, if so.
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DaveReidUK - Correct. This was sequential common cause failures.
galaxy flyer - Yes, I think the entire crew was curious about a possible failure mode; and were party to the N1 indicator failure scenario, which they simulated by pulling a c/b.
What is not really known is why the #3 fan accelerated to a destructive (resonance) speed. GE was never able to replicate that.
galaxy flyer - Yes, I think the entire crew was curious about a possible failure mode; and were party to the N1 indicator failure scenario, which they simulated by pulling a c/b.
What is not really known is why the #3 fan accelerated to a destructive (resonance) speed. GE was never able to replicate that.
Airbus 380 loses engine, goes 5000 miles
I think the real question is what would the proclaimers have done?
The don
The don
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don
I would have probably carried on just the same way, because it must have made sense. Not without constantly having in the back of my mind what Tech Me has nicely put though, and that is what I tried to bring up for discussion and not dissection.
It worries me that this is brushed aside so quickly and fervently, not to say condescendingly.
Sometimes it reminds me of the ominous “ … four legs good, two legs bad …”, only to see the same proclaimers later trying to stand up on two legs themselves ……..
I would have probably carried on just the same way, because it must have made sense. Not without constantly having in the back of my mind what Tech Me has nicely put though, and that is what I tried to bring up for discussion and not dissection.
It worries me that this is brushed aside so quickly and fervently, not to say condescendingly.
Sometimes it reminds me of the ominous “ … four legs good, two legs bad …”, only to see the same proclaimers later trying to stand up on two legs themselves ……..
Sorry Glofish,
I was thinking more of the spectacle wearing Scot brothers. I know they would walk 500 miles, am just wondering if they would try for the 5000 as stated in the title. It was posted early in the morning ok, don't judge me!!!
I can guarantee that the dudes in the 380 didn't just continue on regardless. Lots of thought, consideration, calculations and consultation would have taken place while decision making.
As an aside the continuation policy and its relevant considerations are taught when doing 340 or 380 courses. So the flight deck members have a very good handle of what's required.
I was thinking more of the spectacle wearing Scot brothers. I know they would walk 500 miles, am just wondering if they would try for the 5000 as stated in the title. It was posted early in the morning ok, don't judge me!!!
I can guarantee that the dudes in the 380 didn't just continue on regardless. Lots of thought, consideration, calculations and consultation would have taken place while decision making.
As an aside the continuation policy and its relevant considerations are taught when doing 340 or 380 courses. So the flight deck members have a very good handle of what's required.
don
Don't worry, some of us got the joke..
Sounds reasonable to me.
Don't worry, some of us got the joke..
I can guarantee that the dudes in the 380 didn't just continue on regardless. Lots of thought, consideration, calculations and consultation would have taken place while decision making.
To have one engine remaining on any multi engine jet transport is a serious situation, the big twins are certified to operate on one and land as soon as possible.
This is why ETOPS was invented, to cater and allow for an unthinkable possibility in the age of three and four engine jets.
Those earlier aircraft had built in redundancy allowing you to continue with the loss of one powerplant.
Nothing has changed except the 'twin minded' assume every engine failure is an emergency regardless of how many you have remaining.
This is why ETOPS was invented, to cater and allow for an unthinkable possibility in the age of three and four engine jets.
Those earlier aircraft had built in redundancy allowing you to continue with the loss of one powerplant.
Nothing has changed except the 'twin minded' assume every engine failure is an emergency regardless of how many you have remaining.
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In the last 6 years I can think of 3 accidents in twin engined aircraft caused by total engine failure in flight, a 777, An Airbus A320 and a Boeing 737.
Since 4 engine commercial jet airliners started flying in the 1960s I cannot think of one accident on a 4 engined jet airliner due to multiple engine failure resulting in insufficient thrust to remain airborne. I am not counting fuel exhaustion as those were not mechanical failures of the engine.
Engines were not so reliable back in those days and 707's and the early 747's did sometimes lose one or two engines. There is a big difference between an uncontained engine failure with adjacent damage which is the scenario some people seem to be thinking about on this forum and an engine that has been shut down by the flight crew due to low oil pressure, high vibration, high temperature etc.
In the past before the days of the internet a lot of 4 engined aircraft would have carried on to destination after an engine failure with their passengers blissfully ignorant and the general public unaware. The pilots would have used their skill and judgement to decide whether to continue or not and unqualified people on forums who have never flown jet airliners would not be thinking they knew better than the pilots.
Since 4 engine commercial jet airliners started flying in the 1960s I cannot think of one accident on a 4 engined jet airliner due to multiple engine failure resulting in insufficient thrust to remain airborne. I am not counting fuel exhaustion as those were not mechanical failures of the engine.
Engines were not so reliable back in those days and 707's and the early 747's did sometimes lose one or two engines. There is a big difference between an uncontained engine failure with adjacent damage which is the scenario some people seem to be thinking about on this forum and an engine that has been shut down by the flight crew due to low oil pressure, high vibration, high temperature etc.
In the past before the days of the internet a lot of 4 engined aircraft would have carried on to destination after an engine failure with their passengers blissfully ignorant and the general public unaware. The pilots would have used their skill and judgement to decide whether to continue or not and unqualified people on forums who have never flown jet airliners would not be thinking they knew better than the pilots.
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In the last 6 years I can think of 3 accidents in twin engined aircraft caused by total engine failure in flight, a 777, An Airbus A320 and a Boeing 737.
Since 4 engine commercial jet airliners started flying in the 1960s I cannot think of one accident on a 4 engined jet airliner due to multiple engine failure resulting in insufficient thrust to remain airborne. I am not counting fuel exhaustion as those were not mechanical failures of the engine.
Engines were not so reliable back in those days and 707's and the early 747's did sometimes lose one or two engines. There is a big difference between an uncontained engine failure with adjacent damage which is the scenario some people seem to be thinking about on this forum and an engine that has been shut down by the flight crew due to low oil pressure, high vibration, high temperature etc.
In the past before the days of the internet a lot of 4 engined aircraft would have carried on to destination after an engine failure with their passengers blissfully ignorant and the general public unaware. The pilots would have used their skill and judgement to decide whether to continue or not and unqualified people on forums who have never flown jet airliners would not be thinking they knew better than the pilots.
Since 4 engine commercial jet airliners started flying in the 1960s I cannot think of one accident on a 4 engined jet airliner due to multiple engine failure resulting in insufficient thrust to remain airborne. I am not counting fuel exhaustion as those were not mechanical failures of the engine.
Engines were not so reliable back in those days and 707's and the early 747's did sometimes lose one or two engines. There is a big difference between an uncontained engine failure with adjacent damage which is the scenario some people seem to be thinking about on this forum and an engine that has been shut down by the flight crew due to low oil pressure, high vibration, high temperature etc.
In the past before the days of the internet a lot of 4 engined aircraft would have carried on to destination after an engine failure with their passengers blissfully ignorant and the general public unaware. The pilots would have used their skill and judgement to decide whether to continue or not and unqualified people on forums who have never flown jet airliners would not be thinking they knew better than the pilots.
"Incident: Airbridge Cargo B748 near Hong Kong on Jul 31st 2013, both left hand engines surged at same time, one right hand engine damaged too"
Incident: Airbridge Cargo B748 near Hong Kong on Jul 31st 2013, both left hand engines surged at same time, one right hand engine damaged too
This poorly handled icing software glitch could have occurred in the ITCZ over mid-Atlantic then the story may have had a different outcome.
This is called a common mode failure. ALL aircraft with software controls that have been built on prior assumptions - even if the software is dual designed for resilience - can suffer these failures. Yes they are rare but when a software failure like this occurs ALL your software controlled super reliable engines are likely to go. Are even your engineers on telemetry to your engines aware of the wrong assumptions made by the analysts, software designers, programmers and verification testers?
And yes this affects aircraft with all numbers of engines - but in this case having more engines does not necessarily save you. You could be flying aircraft with 4 glass jawed engines and be totally unaware until the 'wrong' sequence of events hit them and the software makes the wrong decision.
As I said earlier Fault tolerance, resilience and reliability are interesting fields and basic frequentist statistics bear NO relation to probabilities of failure in complex fault trees.
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I'd have been pretty comfortable with it, too, I think.
To be fair to the crew none of us were there - THEY make the decisions dependent upon the information that THEY had available to them from a multitude of sources.
Whether it be DODAR, FORDEC, GRADE, DECIDE or some other process, they will have had a decision making process to follow that will have weighed up the risk and benefits of the situation. It is, after all, why they are on board in the first place.
To be fair to the crew none of us were there - THEY make the decisions dependent upon the information that THEY had available to them from a multitude of sources.
Whether it be DODAR, FORDEC, GRADE, DECIDE or some other process, they will have had a decision making process to follow that will have weighed up the risk and benefits of the situation. It is, after all, why they are on board in the first place.
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I can't see anything in the linked page which explicitly specifies a software "glitch". Do you have information confirming that?