Airbus 380 loses engine, goes 5000 miles
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Although I think the incident was handled well and according regulations and procedures, let’s not forget:
4 engines have double the probability of an engine failure than 2 engines.
3 engines still have a higher probability of one failing than a twin.
Engines working on higher cruise thrust have a higher probability of failure again.
A 4-holer flying with only 2 has less performance than a twin on one hole, per design.
A 4-holer is not ETOPS certified, thus when losing the second hole, is in uncharted territory and on a full blown emergency.
That leads me to conclude that if you lose an engine on a 4-holer, you can continue, but you would be best advised to get into a 60min circle of a suitable airport within a reasonable time. This is not regulation, but looking at the situation from the above side, continuing over extended waters or high terrain on 3 holes might be legal and economic, but certainly not the safest solution.
(I remember faintly that on 3-holers we had en exemption for 120min until we had to be within 60min of a suitable airport, that makes some sense)
4 engines have double the probability of an engine failure than 2 engines.
3 engines still have a higher probability of one failing than a twin.
Engines working on higher cruise thrust have a higher probability of failure again.
A 4-holer flying with only 2 has less performance than a twin on one hole, per design.
A 4-holer is not ETOPS certified, thus when losing the second hole, is in uncharted territory and on a full blown emergency.
That leads me to conclude that if you lose an engine on a 4-holer, you can continue, but you would be best advised to get into a 60min circle of a suitable airport within a reasonable time. This is not regulation, but looking at the situation from the above side, continuing over extended waters or high terrain on 3 holes might be legal and economic, but certainly not the safest solution.
(I remember faintly that on 3-holers we had en exemption for 120min until we had to be within 60min of a suitable airport, that makes some sense)
Glofish
Glofish, your conclusions are not applicable - you're now into another universe with probability stats if you start to look at two engine failures on a four engine aircraft on the same flight.
You probably have a far higher chance of being hit by a meteorite.
As an industry we generally don't do, if, if, if and if and that's what is being done in this thread - there is no evidence that there is a problem here nor that engine out flight has been dealt with other than with successful outcomes.
The statistical probability calculations argue that we've more chance of an engine failure in a 3 or 4 engine aircraft etc - well, that's good, the 747 gets "safer" after it's engine failure.
Don't forget that the engine failure stats/data on which ETOPS was founded did not include many failures such as the engine stopping due to a gearbox malfunction etc - the engine had stopped and it was not possible to start it again but as it wasn't a "core engine" problem it didn't count
PS there are regs to be complied with if you lose another engine including drift down on two ..... at high weights on two engines most aircraft like the 747, A340 etc need a drift down altitude of circa 10-15,000 feet - there is still a safety net.
You probably have a far higher chance of being hit by a meteorite.
As an industry we generally don't do, if, if, if and if and that's what is being done in this thread - there is no evidence that there is a problem here nor that engine out flight has been dealt with other than with successful outcomes.
The statistical probability calculations argue that we've more chance of an engine failure in a 3 or 4 engine aircraft etc - well, that's good, the 747 gets "safer" after it's engine failure.
Don't forget that the engine failure stats/data on which ETOPS was founded did not include many failures such as the engine stopping due to a gearbox malfunction etc - the engine had stopped and it was not possible to start it again but as it wasn't a "core engine" problem it didn't count
PS there are regs to be complied with if you lose another engine including drift down on two ..... at high weights on two engines most aircraft like the 747, A340 etc need a drift down altitude of circa 10-15,000 feet - there is still a safety net.
Last edited by Good Business Sense; 14th Nov 2013 at 08:14.
My only personal experience of prolonged flight with an engine inop was on a DC10 trans-atlantic. We soon noted a very significant increase in oil consumption, due due breakdown of the labyrinth seals for the windmilling engine. However, we soon established the oil loss to be at at a constant and predictable rate and on this basis continued to destination while closely monitoring oil contents.
No sweat, no drama.
No sweat, no drama.
Glofish, your conclusions are not applicable - you're now into another universe with probability stats if you start to look at two engine failures on a four engine aircraft on the same flight.
You probably have a far higher chance of being hit by a meteorite.
You probably have a far higher chance of being hit by a meteorite.
Yes, of course the a priori probability of two successive, unrelated engine failures in the same flight is extremely low (in effect it's a very small number multiplied by an almost as small number).
But we're talking instead about the conditional probability of a second failure given that one engine has already failed. Since the probability of something that has already happened is 100%, we are now talking about one small number, not two small numbers multiplied together.
Good introduction to Conditional Probability here:
https://en.wikipedia.org/wiki/Conditional_probability
DaveReidUK
Need to read what I wrote;
I was debating his conclusions !
Didn't say he was wrong on those statements (indeed I agreed with them) in the first part of the post re : engine failure on a "four engine aircraft", engine failure on a "three engined aircraft" and engine failure on a "two engined aircraft" (had all three happen)
but, the argument moved on to apply some interesting conclusions to another completely different scenario and the getting inside a 60 minute circle (why 60) from an airport because you're down to three engines !!
Having spent considerable time on one engine after an engine failure on a twin (more than once) and also on three engines after engine failure on a quad (more than once) I know where I'd rather be. Remember, this thread is about continuing with three engines on a four engine aircraft in a world that allows almost unlimited flight on one engine with circa 350 people down the back.
I've asked twice already but I'll try again, have there been problems with continuing on three engines - any examples ? I know someone mentioned a constellation a couple of pages back but.....
I was debating his conclusions !
Didn't say he was wrong on those statements (indeed I agreed with them) in the first part of the post re : engine failure on a "four engine aircraft", engine failure on a "three engined aircraft" and engine failure on a "two engined aircraft" (had all three happen)
but, the argument moved on to apply some interesting conclusions to another completely different scenario and the getting inside a 60 minute circle (why 60) from an airport because you're down to three engines !!
Having spent considerable time on one engine after an engine failure on a twin (more than once) and also on three engines after engine failure on a quad (more than once) I know where I'd rather be. Remember, this thread is about continuing with three engines on a four engine aircraft in a world that allows almost unlimited flight on one engine with circa 350 people down the back.
I've asked twice already but I'll try again, have there been problems with continuing on three engines - any examples ? I know someone mentioned a constellation a couple of pages back but.....
Last edited by Good Business Sense; 14th Nov 2013 at 10:23.
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GBS
Your last question is a rhetoric one. I could just as much ask stupidly if continuing with only one on a twin was that much of a problem .... examples EY and a Kenian a few years back and nothing happened either.
I was debating the risk present when deciding to legally continue on three with a 4-holer.
1. I did not read or hear anyone considering the increased risk of failure on the remaining engines due to higher rpm and egt. Why would we derate on T/O if not to increase lifetime and cruising for 12 hours on higher rpm and egt certainly reduces lifetime and increases risk of something turning sour.
2. i pointed at the fact that when you lose the second engine on a 4-holer you are in a less comfortable situation than with a twin losing its first, simply because the latter's power ratio is better on one and its systems are more specifically designed to handle such a situation (ETOPS).
This puts you on a higher risk situation than on a twin for two reasons, therefore my conclusion that continuing over extended waters or terrain might not be the best solution. As simple as that.
I think that it is certainly possible to continue, but some 4-hole jockeys seem a little too enthusiastic about this capability. Just some points to maybe consider a little bit closer.
Your last question is a rhetoric one. I could just as much ask stupidly if continuing with only one on a twin was that much of a problem .... examples EY and a Kenian a few years back and nothing happened either.
I was debating the risk present when deciding to legally continue on three with a 4-holer.
1. I did not read or hear anyone considering the increased risk of failure on the remaining engines due to higher rpm and egt. Why would we derate on T/O if not to increase lifetime and cruising for 12 hours on higher rpm and egt certainly reduces lifetime and increases risk of something turning sour.
2. i pointed at the fact that when you lose the second engine on a 4-holer you are in a less comfortable situation than with a twin losing its first, simply because the latter's power ratio is better on one and its systems are more specifically designed to handle such a situation (ETOPS).
This puts you on a higher risk situation than on a twin for two reasons, therefore my conclusion that continuing over extended waters or terrain might not be the best solution. As simple as that.
I think that it is certainly possible to continue, but some 4-hole jockeys seem a little too enthusiastic about this capability. Just some points to maybe consider a little bit closer.
1. I did not read or hear anyone considering the increased risk of failure on the remaining engines due to higher rpm and egt
2. i pointed at the fact that when you lose the second engine on a 4-holer you are in a less comfortable situation than with a twin losing its first, simply because the latter's power ratio is better on one and its systems are more specifically designed to handle such a situation (ETOPS).
This puts you on a higher risk situation for two reasons than on a twin,
2. i pointed at the fact that when you lose the second engine on a 4-holer you are in a less comfortable situation than with a twin losing its first, simply because the latter's power ratio is better on one and its systems are more specifically designed to handle such a situation (ETOPS).
This puts you on a higher risk situation for two reasons than on a twin,
Having had an engine failure with a depres at the same time on a twin due air system redundancy problems I'll have to disagree with your comments on ETOPS redundancy - won't even get into ETOPS "dispatch" criteria
Give me lots of hydraulic, electric and air systems any day - this is where the argument goes wrong ...... i.e. viewing the failure of the "power" plant in isolation - n.b. the development of the ETOPS statistical debate was made by ignoring engine failures caused by anything that wasn't a "core" engine fault.
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Bottom line is they kept diversion and delay compensation costs to a min and arrived at destination only 5 hours late. Apparently the economic engine is much more important than engine #4.
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GSD
If you want to compare with a Twin, your choice, but then again a Twin with a failure lands asap!! So comparison falls short.
I am saying that just because a 4-holer has more redundancy and is not legally bound to land, considering what i mentioned above, it is not automatically a good choice to continue over ........ but i realise i am talking against a 4-hole wall.
If you want to compare with a Twin, your choice, but then again a Twin with a failure lands asap!! So comparison falls short.
I am saying that just because a 4-holer has more redundancy and is not legally bound to land, considering what i mentioned above, it is not automatically a good choice to continue over ........ but i realise i am talking against a 4-hole wall.
Glofish,
- I think we'll have to differ on that one. Can't get my head around three is riskier than one ... after you've lost one.
LAND ASAP is almost academic over the Pacific, Poles etc when the nearest usable is 1500+ miles away - 1500+ on one is a long way.... no, if I had the "choice" I'd rather have three.
Like you (I'm guessing) I've got quite a few thousand hours on wide body twins doing ETOPS (which I enjoyed and have no problems with) - but you can't beat starting with four
This puts you on a higher risk situation than on a twin
LAND ASAP is almost academic over the Pacific, Poles etc when the nearest usable is 1500+ miles away - 1500+ on one is a long way.... no, if I had the "choice" I'd rather have three.
Like you (I'm guessing) I've got quite a few thousand hours on wide body twins doing ETOPS (which I enjoyed and have no problems with) - but you can't beat starting with four
Isn't probability of losing 2 engines the same on quad or twin?
I mean.. probably the engines and plane don't know how many are fitted.
Except that doing that on a twin wins you a headline title, on a quad only a pprune topic.
I mean.. probably the engines and plane don't know how many are fitted.
Except that doing that on a twin wins you a headline title, on a quad only a pprune topic.
I think we'll have to differ on that one. Can't get my head around three is riskier than one
It's perfectly legitimate to agree to differ on the degree of weighting that you attach to each of these factors.
Clearly you are correct in that the consequences of losing your one remaining engine on a twin are considerably more serious than the consequences of losing a second engine on a 4-engined aircraft.
Equally, Glofish is correct in saying that the likelihood of losing a second engine is higher (albeit still extremely remote) when there are 3 potential candidates than when there is only one.
DaveReidUK
Been doing risk assessments for years - It's not the definitions, it's the application of logic.... but I now understand where they come from - I could be wrong but I think Glofish may fly a wide body twin on ETOPS so it's a bit rich and quite incredible he makes the comments below ... no cred I'm afraid
Glofish said:
Been doing risk assessments for years - It's not the definitions, it's the application of logic.... but I now understand where they come from - I could be wrong but I think Glofish may fly a wide body twin on ETOPS so it's a bit rich and quite incredible he makes the comments below ... no cred I'm afraid
Glofish said:
That leads me to conclude that if you lose an engine on a 4-holer, you can continue, but you would be best advised to get into a 60min circle of a suitable airport within a reasonable time. This is not regulation, but looking at the situation from the above side, continuing over extended waters or high terrain on 3 holes might be legal and economic, but certainly not the safest solution.
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Let me raise a different issue. The plane eventually had to divert to Kuwait -- presumably because it could not manage the additional 530 miles to Dubai. Unless Baghdad is an acceptable diversion destination for an EK A380, this means that for the roughly 1000 miles prior to reaching Kuwait, this bird had no good diversion airports available. Does anyone think this might represent sketchy decisionmaking?
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Sir: If I read your short answer correctly, the availability of diversion airports along the flight path plays no role in decisionmaking as to whether to continue a 3 out of 4 flight?
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They didn't make "an emergency landing due to desperate fuel shortage"
they made a planned landing within the duration of their SAFE fuel reserves......saved their pax a huge amount of delay and inconvenience...saved the operator a fortune and probably gave time for logistics to organise the last 450-mile shuttle "home"
as a mere industry outsider, I can only see positives in this decision.....had they been in a two-engined machine, I would have looked at it somewhat differently.
they weren't...I didn't.
they made a planned landing within the duration of their SAFE fuel reserves......saved their pax a huge amount of delay and inconvenience...saved the operator a fortune and probably gave time for logistics to organise the last 450-mile shuttle "home"
as a mere industry outsider, I can only see positives in this decision.....had they been in a two-engined machine, I would have looked at it somewhat differently.
they weren't...I didn't.