Qantas Twin Dangers~Ben Sandilands
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So if there are question marks over safely operating a four engined jet across the pacific with outsourced maintenance, wouldn't operating a twin engined jet across the pacific with outsourced maintenance be really really dangerous? Maybe I missed it but I don't recall the column from Ben criticising V Australia for doing this and just searched for his comments on the April 15th incident when V had an engine failure at LA, seems it never even warranted a column from Ben. Leaves me wondering if Ben is truly objective.
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For a start QAN S/H, the VA aircraft in LA suffered an engine surge, not an engine failure.
2ndly, a 2 engine aircraft has a bit less than half the chance of suffering an engine failure when compared to a 4-engine aeroplane. Added to this is the requierment for a route/distance limitation, higher standards of inspection and airwothiness for EDTO, additional systems redundancies...
The result is that a new 2-engine aeroplane operating under EDTO is just as safe, if not safer, than a 4 engine on a similar route.
Your lack of knowledge of this sort of thing is a little bit disturbing if you are in airline management, as I and many others suspect you to be.
2ndly, a 2 engine aircraft has a bit less than half the chance of suffering an engine failure when compared to a 4-engine aeroplane. Added to this is the requierment for a route/distance limitation, higher standards of inspection and airwothiness for EDTO, additional systems redundancies...
The result is that a new 2-engine aeroplane operating under EDTO is just as safe, if not safer, than a 4 engine on a similar route.
Your lack of knowledge of this sort of thing is a little bit disturbing if you are in airline management, as I and many others suspect you to be.
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Anthill,
Ok, happy to stand corrected on the engine failure. But, whether a twin engine is just as safe as a 4 engine jet is not the point. Under normal operating circumstances I entirely agree with you. But the issue here is whether outsourced engine maintenance results in a far higher risk of failure, as Ben's column implies, and if it did then a twin engine jet would be far riskier than a 4 engine jet. And if you were genuinely worried about the dangers of outsourced engine maintenance, as Ben seems to be, then you should surely be most concerned about those using it on twin engine jets.
Ok, happy to stand corrected on the engine failure. But, whether a twin engine is just as safe as a 4 engine jet is not the point. Under normal operating circumstances I entirely agree with you. But the issue here is whether outsourced engine maintenance results in a far higher risk of failure, as Ben's column implies, and if it did then a twin engine jet would be far riskier than a 4 engine jet. And if you were genuinely worried about the dangers of outsourced engine maintenance, as Ben seems to be, then you should surely be most concerned about those using it on twin engine jets.
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Dealt with Tubby Ward when he was CEO of QF , a Gentleman in every sense of the word , around the same time I met Peter Harbinson , I found him to be an objecive reporter and a down to earth man . At this time I also met Mr Sandilands , a very pompous self opiniated reporter . Nuff said really!
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really
Ant I think you would have a hard time convincing most that
a 2 eng plane is safer than a 4 eng plane over the pond ???
The result is that a new 2-engine aeroplane operating under EDTO is just as safe, if not safer, than a 4 engine on a similar route.
a 2 eng plane is safer than a 4 eng plane over the pond ???
The result is that a new 2-engine aeroplane operating under EDTO is just as safe, if not safer, than a 4 engine on a similar route.
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QAN, I don't follow you. With 4 engines, there is slighly more than twice the probability of an engine failure than on a 2 engined aeroplane. As the 2 engine aeroplane operating under 180 mins EDTO rules has comparable remaining redundancy (electrical/hydraulic/pressurisation) on a single engine as does a 4 engine aeroplane operating with one inoperative.
If what you mean is that a 2nd engine failure on a 2 engine aeroplane will be catastrophic, then I see where you are going with your train of thought. Without getting too far off topic, new engines, such as the GE90, are extremely reliable. An old engine on a 4 engine aircraft that has been badly maintained will probably not develop full Max Continuous Thrust. Further, operation at MCT may overload the engine to the point where a second (or 3rd and 4th!) engine failure occurs. Assuming terrain clearance is ok, it may be prudent to operate the functioning engines at less than MCT during a diversion or continuation senario.
At high weights, a double engine failure on a 4 engine aeroplane will result in a book figure driftdown to a shockingly low altitude (below 10,000'). Add issues such as increased drag from an old airframe...well, it could get pretty ugly. Due to the reduced performance of 4 engine aircraft compared to twins( see CAO 20.1.7B), a 2 engine approach in a 4 engine aircraft is far more hazardous than a single engine appraoch in a twin. Remember that aircraft performance is based on a book figure derived from testing a brand new aeroplane (even more reason why a quality maintenance provider should always be used). For these reasons, a twin is at least as safe as a 4 engine aeroplane. Probably safer - especially if the Twin is new.
If what you mean is that a 2nd engine failure on a 2 engine aeroplane will be catastrophic, then I see where you are going with your train of thought. Without getting too far off topic, new engines, such as the GE90, are extremely reliable. An old engine on a 4 engine aircraft that has been badly maintained will probably not develop full Max Continuous Thrust. Further, operation at MCT may overload the engine to the point where a second (or 3rd and 4th!) engine failure occurs. Assuming terrain clearance is ok, it may be prudent to operate the functioning engines at less than MCT during a diversion or continuation senario.
At high weights, a double engine failure on a 4 engine aeroplane will result in a book figure driftdown to a shockingly low altitude (below 10,000'). Add issues such as increased drag from an old airframe...well, it could get pretty ugly. Due to the reduced performance of 4 engine aircraft compared to twins( see CAO 20.1.7B), a 2 engine approach in a 4 engine aircraft is far more hazardous than a single engine appraoch in a twin. Remember that aircraft performance is based on a book figure derived from testing a brand new aeroplane (even more reason why a quality maintenance provider should always be used). For these reasons, a twin is at least as safe as a 4 engine aeroplane. Probably safer - especially if the Twin is new.
Careful Ben S...
I'm glad you're out there asking & saying what others won't, but you too must get your facts straight if seeking to remain credible.
The statement referring to QF1 in BKK "with three engines shut down, and one spooling up" as they ran off the runway is, I believe, patently wrong. It is my understanding that the aircraft captain selected idle thrust on three engines having accidentally missed grabbing one of the thrust levers. That situation was resolved shortly after when the F/O retarded the remaining engine to idle. The rest is history. The final conclusions have been analysed ad nauseum; there were definite procedural lapses, errors and many contributing factors with the most robust criticisms levelled at management.
I trust you will keep chipping at the deceptive veneer and evasive misrepresentation perpetuated by the spin-kings; just keep your cred as you do it please.
The statement referring to QF1 in BKK "with three engines shut down, and one spooling up" as they ran off the runway is, I believe, patently wrong. It is my understanding that the aircraft captain selected idle thrust on three engines having accidentally missed grabbing one of the thrust levers. That situation was resolved shortly after when the F/O retarded the remaining engine to idle. The rest is history. The final conclusions have been analysed ad nauseum; there were definite procedural lapses, errors and many contributing factors with the most robust criticisms levelled at management.
I trust you will keep chipping at the deceptive veneer and evasive misrepresentation perpetuated by the spin-kings; just keep your cred as you do it please.
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OK:
To calculate the probability of engine failure on a 4 eng. aircraft compared to a twin:
A twin can suffer an engine failure senario in the following ways: Eng 1 can fail, Eng 2 can fail or Eng 1 & 2 can fail. For a 4 engine aircraft, the possible combinations becomes Eng 1, 2, 3, or 4. However, account needs to be taken of 2 engines failing (12 possible combinations), 3 engines failing (4 possible combinations) & all 4 engines failing.
This is why a 4 engine aeroplane has more that twice the chance of engine failure than a twin - assuming that each engine has the same probability of failure..
To calculate the probability of engine failure on a 4 eng. aircraft compared to a twin:
A twin can suffer an engine failure senario in the following ways: Eng 1 can fail, Eng 2 can fail or Eng 1 & 2 can fail. For a 4 engine aircraft, the possible combinations becomes Eng 1, 2, 3, or 4. However, account needs to be taken of 2 engines failing (12 possible combinations), 3 engines failing (4 possible combinations) & all 4 engines failing.
This is why a 4 engine aeroplane has more that twice the chance of engine failure than a twin - assuming that each engine has the same probability of failure..
Posted by: QAN_Shareholder
But the issue here is whether outsourced engine maintenance results in a far higher risk of failure
But the issue here is whether outsourced engine maintenance results in a far higher risk of failure
QF management refuse to admit that they've made a mistake, so they are about to introduce a range of procedural changes to pilot operations to make the engines "last", including use of idle reverse thrust on landing (once they convince James Strong, QF Board member & CEO at the time of the QF1 accident). The engines are being treated with "kid gloves" just so management can save face.
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Saving Face Over Safety
How dare these repugnant swine even contemplate saving face when their actions could lead to a smoking crater with a red and white tail protrudung from it.
The day that happens there will be no safe place on this planet for them to hide.
Cost/Risk analysis gone mad.They are willing to trade lives for their bon uses.No business should survive where lives are at stake due to arrogance and stupidity
The day that happens there will be no safe place on this planet for them to hide.
Cost/Risk analysis gone mad.They are willing to trade lives for their bon uses.No business should survive where lives are at stake due to arrogance and stupidity
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Anthill,
The failure of both engines is the scenario I was thinking of with the equivalent disaster scenario being the failure of 3 engines on a 4 engine jet. I know the following is very much simplified and exaggerated but if you assume your outsourced maintenance provider starts giving you dud engines periodically such that on average they fail one in every thousand flights. With twin engines one flight in a millions ends in catastrophe whereas for a four engine jet I think it would be one flight in every 250 million.
The failure of both engines is the scenario I was thinking of with the equivalent disaster scenario being the failure of 3 engines on a 4 engine jet. I know the following is very much simplified and exaggerated but if you assume your outsourced maintenance provider starts giving you dud engines periodically such that on average they fail one in every thousand flights. With twin engines one flight in a millions ends in catastrophe whereas for a four engine jet I think it would be one flight in every 250 million.
With twin engines one flight in a millions ends in catastrophe whereas for a four engine jet I think it would be one flight in every 250 million.
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Without wishing to enter the twin vs triple/four engine debate,the change from ETOPS to EDTO is a reflection of the change of emphasis from engine reliability to cargo fire suppression.
EDTO removes twin engine from the equation due modern engine design.
sorry,can't remember the relevant ICAO paper.
EDTO removes twin engine from the equation due modern engine design.
sorry,can't remember the relevant ICAO paper.
I don't see VOz engines disintergrate on a regular basis. I have no proof but the number of RB211s disintergrating suggests that there is a problem with the maintenance or the oversight of the maintenance. Anecdotal evidence seems to be sufficient to prove the point. Jet engines are supposed to be reliable not explode on the wing. The common link to all these failures seems to be the intials RR.