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Whats Your Opinion On Etops?  
User currently offlineN821NW From , joined Dec 1969, posts, RR:
Posted (1 year 7 months 1 week 3 days 11 hours ago) and read 11863 times:

I was wondering what was everybody at A.net opinion on the ETOPS program.

I personally love the ETOPS program and would fly a ETOPS jet over a four engine one any day because in my opinion since they are ETOPS certified they are (maybe) better maintained then a quad-jet, and for a bonus they are better for the environment.

However somebody (Richard Wyeroski) thinks that ETOPS is SUPER dangerous and that it is only a matter of time before a ETOPS jet crashes into the ocean killing everybody on-board...supposedly he has proof that ETOPS is a "ticking time bomb" (I think that all his "proof" is rubbish but that is just my opinion), he hates ETOPS so much he even created a ranting forum about it, please read it and tell me what think about it.
http://airnation.net/hangar/threads/...-engines-are-better-than-two.1343/

@Moderators: If I did ANYTHING wrong please delete this thread.

102 replies: All unread, showing first 25:
 
User currently offlinelightsaber From United States of America, joined Jan 2005, 13552 posts, RR: 100
Reply 1, posted (1 year 7 months 1 week 3 days 11 hours ago) and read 11795 times:
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Why are we still debating ETOPS? Its *proven* safe. The added maintenance requirements that ETOPS imposed have found there way into 4 engine operations. The next stage will be more narrowbody ETOPS. The only people who have an issue with ETOPS tend to be those with an economic incentive to favor established airframes or airlines vs. new competition.

There is no turning back the clock. As much as the A310/767/A330/777 opened up the globe... the 787 and A350 will do far more.

I refuse to read a rant. ETOPS is based on statistics that have proven themselves out. The majority of TATL traffic has been ETOPS for a long time.

I'm unlikely to post further on this thread.

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently offlineb2319 From China, joined Jan 2013, 150 posts, RR: 0
Reply 2, posted (1 year 7 months 1 week 3 days 10 hours ago) and read 11685 times:

Quoting lightsaber (Reply 1):
Why are we still debating ETOPS? Its *proven* safe.

Possibly the airline industry's equivalent of the MMR (measles, mumps, rubella) vaccine?

I'm not going to look by, either.

Move along, folks, nothing to see here.....

B-2319


User currently offlinetonystan From Ireland, joined Jan 2006, 1448 posts, RR: 2
Reply 3, posted (1 year 7 months 1 week 3 days 9 hours ago) and read 11555 times:

ETOPS has been around over 20 years. Does it seriously need validating at this stage?


My views are my own and do not reflect any other person or organisation.
User currently offlineFlighty From United States of America, joined Apr 2007, 8776 posts, RR: 3
Reply 4, posted (1 year 7 months 1 week 3 days 8 hours ago) and read 11447 times:

Quoting N821NW (Thread starter):
he has proof that ETOPS is a "ticking time bomb"

So are automobiles. Full of flammable liquids.

Also, the electricity inside computers can be very, very dangerous. Alternating current is very dangerous.

Hope that guy does not use automobiles or use electricity when he makes posts on the internet?


User currently offlineDeltal1011man From United States of America, joined Sep 2005, 9700 posts, RR: 15
Reply 5, posted (1 year 7 months 1 week 3 days 8 hours ago) and read 11445 times:

Quoting N821NW (Thread starter):
ETOPS jet over a four engine one any day because in my opinion since they are ETOPS certified they are (maybe) better maintained then a quad-jet,

not really. Most of the airlines maintain the (limited) quads pretty much the same way the ETOPS fleet is done.

Quoting N821NW (Thread starter):
and for a bonus they are better for the environment.

uh... bonus for some......who gives a crap for others.  
Quoting lightsaber (Reply 1):
The added maintenance requirements that ETOPS imposed have found there way into 4 engine operations.

this.

Quoting lightsaber (Reply 1):
Why are we still debating ETOPS? Its *proven* safe

and gets pulled from the airline and or airframe when it becomes unsafe. If it gets to the point of too many in flight shutdowns then the carrier can gets its ETOPS program pulled.



yep.
User currently offlineairbazar From United States of America, joined Sep 2003, 8665 posts, RR: 10
Reply 6, posted (1 year 7 months 1 week 3 days 8 hours ago) and read 11378 times:

Quoting N821NW (Thread starter):
I was wondering what was everybody at A.net opinion on the ETOPS program.

I have no issue with ETOPS. I just hope I never find myself in a position where I have to travel between deep S.America and Australia, or between S.Africa and Australia, in a twin 


User currently onlineStitch From United States of America, joined Jul 2005, 31442 posts, RR: 85
Reply 7, posted (1 year 7 months 1 week 3 days 8 hours ago) and read 11264 times:
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Anything that is likely to bring down a commercial airliner with two engines is probably just as likely to bring down a commercial airliner with three, four or more engines.

User currently offlinehivue From United States of America, joined Feb 2013, 1114 posts, RR: 0
Reply 8, posted (1 year 7 months 1 week 3 days 7 hours ago) and read 11208 times:

Quoting Stitch (Reply 7):
Anything that is likely to bring down a commercial airliner with two engines is probably just as likely to bring down a commercial airliner with three, four or more engines.

Except dual engine failure. 

Seriously, the only issue here is if you can't keep at least one engine on a twin producing adequate power. All other failure modes would result in either (1) safe completion of the flight or (2) a crash/serious incident no matter how many engines you have. And the statistics on engine failures in twins speak for themselves.


User currently offlineTomassjc From United States of America, joined Jan 2010, 911 posts, RR: 2
Reply 9, posted (1 year 7 months 1 week 3 days 7 hours ago) and read 11103 times:
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Quoting hivue (Reply 8):
Except dual engine failure.

Yes indeed, E ngines T urning O r P eople S wimming.....

Tomas SJC



When once you have tasted flight, you will forever walk the Earth with your eyes turned skyward -Leonardo DaVinci
User currently offlinewarden145 From United States of America, joined Aug 2010, 545 posts, RR: 0
Reply 10, posted (1 year 7 months 1 week 3 days 6 hours ago) and read 10978 times:

Quoting hivue (Reply 8):
Except dual engine failure.

  

Quoting Tomassjc (Reply 9):
Yes indeed, E ngines T urning O r P eople S wimming.....

  

My "signature" says it all regarding my opinion of ETOPS. My strongly-held belief is that nothing man-made is perfect, and no matter how much we try to perfect anything, we will never truly reach that point no matter what people are led to believe. Couple that with a strong preference for redundancies, and you result in an almost violent opposition to the concept of oceanic operations in twin-engine aircraft.

I know that some say that you have a greater chance of losing an engine on a four-engine aircraft than a twin. However, that's counterbalanced by the fact that you have a very small chance of losing three engines on a four-engine aircraft, which would put you in an emergency situation similar to losing one engine on a twin. Yes, air travel has gotten safer in recent years, but I don't find that justification for eliminating the redundancy factor. I also know that an independent dual-engine failure hasn't happened yet...but, as far as I'm concerned, the operative word is yet and I don't particularly want to take the chance of being on the flight when it does happen.

I know that others here will ridicule me for this post, but opinions were sought and that's my very strongly held opinion on the subject. For the record, I have gone out of my way and spent hundreds of dollars extra to take an intercontinental flight on a four-engine aircraft because I didn't want to take a chance. Fortunately, courtesy of LH's A380, there's going to be at least one four-engine flight from SFO to Europe for the foreseeable future...



ETOPS = Engine Turns Off, Passengers Swim
User currently offlineairbazar From United States of America, joined Sep 2003, 8665 posts, RR: 10
Reply 11, posted (1 year 7 months 1 week 3 days 6 hours ago) and read 10929 times:

Quoting Stitch (Reply 7):
Anything that is likely to bring down a commercial airliner with two engines is probably just as likely to bring down a commercial airliner with three, four or more engines.

That's true but it wouldn't keep me from soiling my pants if I lost an engine half way between JNB and SYD. Those would be the longest 4 hours of my life 
Quoting hivue (Reply 8):
Except dual engine failure.

  
And when you lose an engine in a twin, typical procedure is to land at the nearest airport (or quad for that matter). So there really is no operational data to show the probability of a dual engine failure in a twin. On top of that the typical TPAC or TATL flight is barely ever above ETOPS 120, which I'm perfectly confortable with.


User currently offlinehivue From United States of America, joined Feb 2013, 1114 posts, RR: 0
Reply 12, posted (1 year 7 months 1 week 3 days 6 hours ago) and read 10894 times:

Quoting airbazar (Reply 11):
So there really is no operational data to show the probability of a dual engine failure in a twin.

No "operational" data maybe, but I believe that part of the process for certifying an aircraft type for ETOPS is the manufacturer droning around the sky for hours on end on a single engine. Also, assessing the probabilities for completely unrelated dual engine failure boils down to assessing the probabilities for single engine failure.


User currently offlineXFSUgimpLB41X From United States of America, joined Aug 2000, 4229 posts, RR: 37
Reply 13, posted (1 year 7 months 1 week 3 days 5 hours ago) and read 10811 times:

Dual engine flameouts have only occurred in situations that would have taken out all of however many engines were installed on the aircraft.

That guy that started the thread on the other forum has an emotional premise where he is looking for any evidence at all to support his emotions.

Take a look at the what he posted for 777 engine out vs. the 744. He's 100% incorrect as when a 747 loses an engine they are doing exactly the same thing as the 777- and typically going to divert as close as possible.



Chicks dig winglets.
User currently offlineBoeingGuy From United States of America, joined Dec 2010, 3258 posts, RR: 7
Reply 14, posted (1 year 7 months 1 week 3 days 5 hours ago) and read 10794 times:

Quoting Tomassjc (Reply 9):
Quoting hivue (Reply 8):
Except dual engine failure.

Yes indeed, E ngines T urning O r P eople S wimming.....

Eating Time of Pacific Sharks


Seriously, this is another sensationalist "The Sky is Falling" debate. There has NEVER been a fatal accident caused by having a twin flying an ETOPS mission. Life is a risk and this is a pretty safe one. I'll bet that same guy drives down the freeway at 70 mph talking on his cell phone.


User currently onlineStitch From United States of America, joined Jul 2005, 31442 posts, RR: 85
Reply 15, posted (1 year 7 months 1 week 3 days 5 hours ago) and read 10785 times:
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Quoting XFSUgimpLB41X (Reply 13):
Take a look at the what he posted for 777 engine out vs. the 744. He's 100% incorrect as when a 747 loses an engine they are doing exactly the same thing as the 777- and typically going to divert as close as possible.

Unless you are British Airways.  

British Airways 747 Flies Again On Three Engines
(by Jacobin777 Mar 4 2005 in Civil Aviation)


User currently offlineskipness1E From United Kingdom, joined Aug 2007, 3322 posts, RR: 1
Reply 16, posted (1 year 7 months 1 week 3 days 5 hours ago) and read 10776 times:

Quoting warden145 (Reply 10):

I know that others here will ridicule me for this post, but opinions were sought and that's my very strongly held opinion on the subject. For the record, I have gone out of my way and spent hundreds of dollars extra to take an intercontinental flight on a four-engine aircraft because I didn't want to take a chance.

Actually the issue is you have not understood the chance you are taking. The ETOPS modern twin is no more of a risk than the remaining ageing B747s or the odd A340. It's actually absurd that with so much flight experience some people still cling to an irrational believe that four engines are safer. The accident that brought down G-YMMM at LHR would have brought down an MD11 or a Quad given the same circumstances.

You need to look closely at the numbers involved. Number of hull losses of B747 vs B777 might be a good bet.


User currently offlineXT6Wagon From United States of America, joined Feb 2007, 3432 posts, RR: 4
Reply 17, posted (1 year 7 months 1 week 3 days 5 hours ago) and read 10741 times:

I think it needs to be applied to ALL commercial jets regardless of engine count. It goes a long way to removing potential sources of single point failure.

User currently offlineXFSUgimpLB41X From United States of America, joined Aug 2000, 4229 posts, RR: 37
Reply 18, posted (1 year 7 months 1 week 3 days 4 hours ago) and read 10728 times:

Quoting Stitch (Reply 15):
Unless you are British Airways.  

British Airways 747 Flies Again On Three Engines (by Jacobin777 Mar 4 2005 in Civil Aviation)

That's why I said "typically."  



Chicks dig winglets.
User currently offlineAeroWesty From United States of America, joined Oct 2004, 20822 posts, RR: 62
Reply 19, posted (1 year 7 months 1 week 3 days 4 hours ago) and read 10670 times:

I didn't have a problem flying the first ETOPS flights in the 1980s, and don't have a problem now.

What I'm not so sure about is if there should be any concern regarding the ever-increasing size of the big twins, considering single-engine performance on take-off and avoiding en route terrain should an engine go out. That simply stems from not having read enough about it, except peripherally reading a few concerns about it here and there which indicate that there are already routing restrictions are in place over some areas. Nothing specific comes to mind, so please don't grill me on where restrictions currently may be, but if there are no such restrictions, I'd be happy to be updated/corrected on that point.



International Homo of Mystery
User currently onlineStitch From United States of America, joined Jul 2005, 31442 posts, RR: 85
Reply 20, posted (1 year 7 months 1 week 3 days 4 hours ago) and read 10670 times:
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Quoting XT6Wagon (Reply 17):
I think it needs to be applied to ALL commercial jets regardless of engine count. It goes a long way to removing potential sources of single point failure.

It has.  

The FAA now classifies ETOPS as ExTended OPerationS and now also applies it to three and four engine commercial airliners with the publication of Advisory Circular 120-42B.

And per an Airbus presentation to the ICAO in October 2011, EASA has LROPS (Long Range OPerations) for three and four engine commercial aircraft and the ICAO has EDTO - Extended Diversion Time Operations for commercial aircraft with two, three or four engines.


User currently offlineXT6Wagon From United States of America, joined Feb 2007, 3432 posts, RR: 4
Reply 21, posted (1 year 7 months 1 week 3 days 4 hours ago) and read 10626 times:

Quoting Stitch (Reply 20):

It has.  

The FAA now classifies ETOPS as ExTended OPerationS and now also applies it to three and four engine commercial airliners with the publication of Advisory Circular 120-42B.

Doesn't require the special procedures for engine MX from my understanding. So one mistake by a mechanic can still leave a 4 engine plane... engineless. Also I'm uncertain if they require immediate diversion now.


User currently offlineSCL767 From Chile, joined Feb 2006, 8862 posts, RR: 5
Reply 22, posted (1 year 7 months 1 week 3 days 3 hours ago) and read 10594 times:

Quoting airbazar (Reply 6):
I just hope I never find myself in a position where I have to travel between deep S.America and Australia, or between S.Africa and Australia, in a twin

Personally, I'm looking forward to crossing the South Pacific in a twin, (B77W and/or B787-9). LATAM will be operating twins between South America and AKL/SYD relatively soon as the company has decided to phase out the last two A343s in the fleet during 2014 instead of during 2015...


User currently offlineXFSUgimpLB41X From United States of America, joined Aug 2000, 4229 posts, RR: 37
Reply 23, posted (1 year 7 months 1 week 3 days 2 hours ago) and read 10458 times:

Quoting AeroWesty (Reply 19):

I didn't have a problem flying the first ETOPS flights in the 1980s, and don't have a problem now.

What I'm not so sure about is if there should be any concern regarding the ever-increasing size of the big twins, considering single-engine performance on take-off and avoiding en route terrain should an engine go out. That simply stems from not having read enough about it, except peripherally reading a few concerns about it here and there which indicate that there are already routing restrictions are in place over some areas. Nothing specific comes to mind, so please don't grill me on where restrictions currently may be, but if there are no such restrictions, I'd be happy to be updated/corrected on that point.

Calculating takeoff performance assumes losing an engine at the worst possible time and assures terrain clearance with that failure.

Flight planning also assures drift down terrain clearance in the event of an engine failure.



Chicks dig winglets.
User currently offlinecsavel From United States of America, joined Jan 2001, 1377 posts, RR: 4
Reply 24, posted (1 year 7 months 1 week 3 days 2 hours ago) and read 10394 times:

Quoting warden145 (Reply 10):
that's counterbalanced by the fact that you have a very small chance of losing three engines on a four-engine aircraft, which would put you in an emergency situation similar to losing one engine on a twin

That just doesn't seem right. If you lose 3 engines on a quad, you've lost 75% of your engine power. If you lose one engine on a twin, you've lost only 50% of your power. Yes, I know that in both situations there is only one engine left, but I'd much rather have that remaining one engine represent half of my engine power as opposed to only 1/4 of my engine power.

One can worry about a lot of things, but this seem very very low on the list.



I may be ugly. I may be an American. But don't call me an ugly American.
User currently offlineXFSUgimpLB41X From United States of America, joined Aug 2000, 4229 posts, RR: 37
Reply 25, posted (1 year 7 months 1 week 3 days 2 hours ago) and read 10877 times:

Quoting csavel (Reply 24):
That just doesn't seem right. If you lose 3 engines on a quad, you've lost 75% of your engine power. If you lose one engine on a twin, you've lost only 50% of your power. Yes, I know that in both situations there is only one engine left, but I'd much rather have that remaining one engine represent half of my engine power as opposed to only 1/4 of my engine power.

One can worry about a lot of things, but this seem very very low on the list.

On top of this, think about the things that would cause more than one engine to fail... If you lose more than one engine, it's highly likely whatever knocked those out is going to take out all of the engines regardless of how many are installed on the aircraft.



Chicks dig winglets.
User currently offlineWesternDC6B From United States of America, joined Mar 2013, 148 posts, RR: 0
Reply 26, posted (1 year 7 months 1 week 2 days 22 hours ago) and read 10064 times:
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Quoting Flighty (Reply 4):
Hope that guy does not use automobiles or use electricity when he makes posts on the internet?

I think using a computer to post on the internet far more practical than an automobile.   

As for ETOPS travel, I hardly give it a second thought. I have not traveled as much as some of you on here, but have still been over the Pacific several times, and over the Atlantic and Med on a few occasions. My main concern is with comfort (I'm a big man), and the track record of the airline. One with a history of using a forklift to take engines on and off of their DC10s - when the manual specifically said not to - is less likely to get my business than one with a superior safety record. As for the number of engines, it is only of interest to me from a technical standpoint, not of safety.

Now, a question: how many multiple engine failures have there been when on transoceanic flights? By this I mean a DC10/MD11 losing two out of three, or a 707/DC8/A340/880/990/VC10/IL62 losing 3 out of 4 engines? I am not considering the one involving, I think, an Airbus 300 where a fuel line fractured and the flight deck crew dis-believed their instruments.

In closing, if one wants engine redundancy on a transoceanic flight, nothing can beat a Dornier X.

[Edited 2013-05-22 19:29:22]


Be kind to animals - Take a grizzly to lunch today.
User currently offlineDeltal1011man From United States of America, joined Sep 2005, 9700 posts, RR: 15
Reply 27, posted (1 year 7 months 1 week 2 days 21 hours ago) and read 10091 times:

Quoting warden145 (Reply 10):
For the record, I have gone out of my way and spent hundreds of dollars extra to take an intercontinental flight on a four-engine aircraft because I didn't want to take a chance.

If this is true I hope you never get in a car or really step outside your house.

Your life is in so much more danger driving to and from the airport than getting on a 767,777,787,330 etc flying to Europe.

There are hundreds if not thousands of ETOPS flights and I can't recall a single time in 20+ years a twin on ETOPS flights has lost both engines when a quad wouldn't have also lost all power.

And in this day in age air travel is so amazingly safe I can't honestly believe someone would go out of their way and spend a ton of extra cash to fly a quad over a twin.
But the good thing is, that is well within your rights. I use to be the same way but all the data points that twin flying is just sa safe.   



yep.
User currently offlineHBGDS From , joined Dec 1969, posts, RR:
Reply 28, posted (1 year 7 months 1 week 2 days 21 hours ago) and read 9851 times:

It all depends what ETOPS you're talking about. It used to be 120. Now it's 180, and a goal of 240 is probably in the works. The accidents that have happened to twins flying ETOPS have all been traced to issues other than the engines themselves.

Personally, I'd like a quad better, but for the past ten years, my ATL runs for biz or fun have been mostly twins, with quads the rare exception. In other words, that is not going to change.


User currently onlineStitch From United States of America, joined Jul 2005, 31442 posts, RR: 85
Reply 29, posted (1 year 7 months 1 week 2 days 20 hours ago) and read 9751 times:
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Quoting HBGDS (Reply 28):
Now it's 180, and a goal of 240 is probably in the works.

ETOPS-240 and ETOPS-330 are already in place with the A330 and 777. NZ, for example, flies their 777s via ETOPS-240 on Los Angeles - Auckland.

http://boeing.mediaroom.com/index.php?s=43&item=2070

http://www.airbus.com/presscentre/pr...fied-for-etops-beyond-180-minutes/

[Edited 2013-05-22 20:43:32]

User currently offlinelightsaber From United States of America, joined Jan 2005, 13552 posts, RR: 100
Reply 30, posted (1 year 7 months 1 week 2 days 20 hours ago) and read 9649 times:
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More than 3.3 million ETOPS twinjets flights have been logged since 1985. Approximately, 125 airline operators perform some 1100 ETOPS flights per day ? over 30,000 flights per month. Performed worldwide, it ranks among the very safest and most reliable of all flight operations.>

And that quote is from 2003!
http://www.boeing.com/news/releases/2003/q4/nr_031015gq&a.html

In millions of flights, where is the issue? The quad safety rate was one crash every million flights. That set the minimum bar for ETOPs. ETOPs has done far better.

A quad adds about 12 tons of weight over a twin. Unless the aircraft is huge, there is no economic payoff.

Quoting warden145 (Reply 10):
My "signature" says it all regarding my opinion of ETOPS.

   As noted most people will not give ETOPs a second thought. You do realize most airlines are phasing out quads? So obviously your preference is rare. e.g., ANA and JAL. BA will replace most 747s with a twin (77W or other large twin) and not a quad.

The most dangerous point of your whole journey is crossing a street on the way to/from the airport.

If you want to fly quads, go for it. I'll fly the most convenient routing. You're very rare if you will pay a premium for most quads. Ok, the A380 is generating interest and I expect that to last for a bit... But partially it is the rarity of the airplane.

For quads in 2013, IIRC there will be 24 delivered A380s and 12 748s. That is it for quads (36 total airframes)
There will be 80 777s
There will be 60 787s
There will be 120 A330s
And some small number of pax 767s (delivered mostly due to 787 delays).

Or just over 7 long haul twins per quad. The 777s alone will have more seats than the quads delivered this year. Next year A330 production increases and we'll see EIS of the A350.

Have your own opinion. But look at the order backlogs

A330 (in April) at 280 per http://www.airbus.com/newsevents/new...-meet-strong-global-market-demand/

787 backlog (per all things 787): 838
A350 backlog (per wikipedia): 670
A380 backlog: 161 (per wiki)
748 backlog: 59
767 backlog; 62
777 backlog: 347 (with 1,096 delivered)

Or 8.7 twins in the backlog per quad.

And I didn't even mention narrowbody ETOPs...

Quoting AeroWesty (Reply 19):

I didn't have a problem flying the first ETOPS flights in the 1980s,

I met test engineers who flew the proving flights.   

Quoting Deltal1011man (Reply 27):
There are hundreds if not thousands of ETOPS flights and I can't recall a single time in 20+ years a twin on ETOPS flights has lost both engines when a quad wouldn't have also lost all power.

Exactly.

Quoting Deltal1011man (Reply 27):
And in this day in age air travel is so amazingly safe I can't honestly believe someone would go out of their way and spend a ton of extra cash to fly a quad over a twin.

   I've flown quads every time over the Atlantic, but that is because on those days the 747 had the cheapest fares... I wanted the 777, but I wasn't willing to pay a premium.

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently offlineDexSwart From Australia, joined Aug 2012, 594 posts, RR: 0
Reply 31, posted (1 year 7 months 1 week 2 days 15 hours ago) and read 8013 times:

Quoting airbazar (Reply 6):
I just hope I never find myself in a position where I have to travel between deep S.America and Australia, or between S.Africa and Australia, in a twin!

Well, firstly, let me say, that I'm a die hard 747 fan. It's sad that I was only born on the later end of the Queen of the Sky's life. Luckily, I can still fly them regularly on QF between SYD and JNB and vice versa. I don't normally mind, but having done MEL - JNB on VA, I must say, it took so much longer to complete that flight due to ETOPS.

I've been subjected to 15 hours 40 minutes on a 747 flying the shortest route safely possible between SYD and JNB. I shudder to think what that would have been had that flight been on a 77W!



Durban. Melbourne. Denver. Hong Kong.
User currently offlineRara From Germany, joined Jan 2007, 2170 posts, RR: 2
Reply 32, posted (1 year 7 months 1 week 2 days 14 hours ago) and read 7861 times:

Safety is always relative. Yes, one day a twin will plunge into the ocean that could have been saved by two additional engines.

Is that reason enough to disallow ETOPS? By the time of a serious accident, how many million tons of fuel will have been saved, how many million Euros saved, how many additional passengers have flown because of lower ticket prices, how many additional routes opened - all due to ETOPS?

In aviation there are always tradeoffs. Of course you could equip every passenger with a parachute. During the next 20 years, it may even save a life or two. The result is not worth the effort! ETOPS is essentially the same. Requiring three or four engines for oceanic flights may mean a marginal safety gain, but the cost in terms of missed business opportunities is much too high to justify it.

All that said, I'd hate to be a passenger on that first ETOPS flight that dips it.  



Samson was a biblical tough guy, but his dad Samsonite was even more of a hard case.
User currently offline3rdGen From Bahrain, joined Jul 2011, 245 posts, RR: 0
Reply 33, posted (1 year 7 months 1 week 2 days 14 hours ago) and read 7621 times:

Can someone please give us an example in the history of twin engine jet aircraft operations in which both engines were lost due to something other than fuel starvation or ingestion of foreign debris?

User currently offlineSmittyOne From , joined Dec 1969, posts, RR:
Reply 34, posted (1 year 7 months 1 week 2 days 12 hours ago) and read 7012 times:

Quoting warden145 (Reply 10):
Couple that with a strong preference for redundancies, and you result in an almost violent opposition to the concept of oceanic operations in twin-engine aircraft.

If it happens over the middle of the Pacific ocean, all that those two remaining engines may do is give you more time to write your goodbye note as you head to the fuel-exhaustion crash site.

Quoting warden145 (Reply 10):
you have a very small chance of losing three engines on a four-engine aircraft, which would put you in an emergency situation similar to losing one engine on a twin.

Not true. Losing TWO engines on a quad is already much worse than losing one engine on a twin. Both would be at "50% of original power", but twins have a substantial reserve of excess power to begin with because they have to be able to takeoff, climb and fly with one engine out. AFAIK, quads are not required to be able to do all that with two engines out (somebody correct me if I'm wrong).

So in general I don't disagree with the concept of 'redundancy', but suggest that you're just not getting as much of it as you think with four engines vs. two.

Here's some more food for thought...

Would the QANTAS A380 that had the uncontained engine failure have made it home with TWO of her engines failing that catastrophically? The answer to that is debatable, but the question tells me that the issue of safety of oceanic flight vs. number of engines is a bit more complex than more = better.


User currently offlinelightsaber From United States of America, joined Jan 2005, 13552 posts, RR: 100
Reply 35, posted (1 year 7 months 1 week 2 days 10 hours ago) and read 6746 times:
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Quoting b2319 (Reply 2):
Possibly the airline industry's equivalent of the MMR (measles, mumps, rubella) vaccine?

Don't get me started on vaccines. If you have a child coming, the pediatricians force the father (too late for mommy) and grandparents to go out and get re-vaccinated as that is the only way to stop MMR and Pertussis. Then again, I live in LA where all but mumps is endemic because so many people are un-vaccinated. (Let's not forget we vaccinate Rubella for what it does to unborn children... Its otherwise a minor illness.)

Quoting Rara (Reply 32):
All that said, I'd hate to be a passenger on that first ETOPS flight that dips it.

But what case would happen that wouldn't have put a quad down? That is the point the pro-quad crowd is ignoring! The *only* case I think of we can argue is there was a mechanic who decided to replace all the oil filters on an A330 at once (forbidden by procedure) and he didn't seat the filters correctly. Such an incident would have happened on a quad too!

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently offlineclydenairways From Ireland, joined Jan 2007, 1296 posts, RR: 0
Reply 36, posted (1 year 7 months 1 week 2 days 10 hours ago) and read 6690 times:

A bit of a strange thread to be starting in 2013, about 30years too late. It's a bit like starting a thread about:
What's your opinion on the Jet Engine?
What's your opinion on only a two man crew?


User currently offlineaaron747 From Japan, joined Aug 2003, 8299 posts, RR: 26
Reply 37, posted (1 year 7 months 1 week 2 days 10 hours ago) and read 6610 times:

Quoting AeroWesty (Reply 19):
What I'm not so sure about is if there should be any concern regarding the ever-increasing size of the big twins, considering single-engine performance on take-off and avoiding en route terrain should an engine go out. That simply stems from not having read enough about it, except peripherally reading a few concerns about it here and there which indicate that there are already routing restrictions are in place over some areas. Nothing specific comes to mind, so please don't grill me on where restrictions currently may be, but if there are no such restrictions, I'd be happy to be updated/corrected on that point.

Are you referring to having sufficient rudder authority on an aircraft like the 77W when losing one engine at the worst possible time? The manufacturers have this covered with warnings to crew in the FOM and established training procedures for dealing with that specific scenario.



If you need someone to blame / throw a rock in the air / you'll hit someone guilty
User currently offline747luvr From United States of America, joined Jul 2005, 394 posts, RR: 0
Reply 38, posted (1 year 7 months 1 week 2 days 10 hours ago) and read 6596 times:

Can a 747 remain in cruise with 3 engines out, to divert to the nearest alternate or would it stall and fall?

User currently offlineN821NW From , joined Dec 1969, posts, RR:
Reply 39, posted (1 year 7 months 1 week 2 days 9 hours ago) and read 6577 times:

Quoting 747luvr (Reply 38):
Can a 747 remain in cruise with 3 engines out, to divert to the nearest alternate or would it stall and fall?

Well I'm no expert but I don't think a B747 would be able to stay at cruising altitude (even a twin when it looses a engine can't) but it would not "stall and fall" it would just slowly drop in altitude, remember that even if a airplane lost ALL its engines it won't stall but glide down.


User currently onlineStitch From United States of America, joined Jul 2005, 31442 posts, RR: 85
Reply 40, posted (1 year 7 months 1 week 2 days 9 hours ago) and read 6598 times:
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Quoting 747luvr (Reply 38):
Can a 747 remain in cruise with 3 engines out, to divert to the nearest alternate or would it stall and fall?

The 747 (and A340 and A380) is (are) perfectly capable of continuing to their original destination with a single engine out and they are not required to divert to an alternate in such a situation (though the flight crew may choose to do so).


User currently offlineB777LRF From Luxembourg, joined Nov 2008, 1475 posts, RR: 3
Reply 41, posted (1 year 7 months 1 week 2 days 9 hours ago) and read 6529 times:

Indeed, but they won't be able to maintain altitude and thus will burn more fuel on 3 than they did on 4, as BA found to their embarrasment, incurring the unwarrented wrath of the FAA at the same time.

I don't particularly have anything against ETOPS, but if an airline offers me a choice of aircraft on which to cross an ocean, I'll take the one with the most engines. Quads flies faster than twins too, generally speaking, making the preference even more clear.



From receips and radials over straight pipes to big fans - been there, done that, got the hearing defects to prove
User currently offliner2rho From Germany, joined Feb 2007, 2776 posts, RR: 1
Reply 42, posted (1 year 7 months 1 week 2 days 8 hours ago) and read 6437 times:

I have no problem with twins and I realize ETOPS is well proven and safe. And as has been said, ETOPS/LROPS standards are no longer exclusive to twins - they have been extended to many quads as well, due precisely to this fact.

But having said that... I don't like the idea of ETOPS 240/330. Regardless of being on a twin or quad, or a Dornier X, and regardless of safety statistics. An engine is not "supposed" to fail, not even a single one. And when it does, it is seldom an isolated event and tends to affect other aircraft systems as well. And in such a situation, I don't like being 240+min away from the next diversion airport (itself likely in a remote area to which help will take long to arrive), no matter how many engines are on the plane.


User currently offlineBoeingGuy From United States of America, joined Dec 2010, 3258 posts, RR: 7
Reply 43, posted (1 year 7 months 1 week 2 days 8 hours ago) and read 6375 times:

Quoting 3rdGen (Reply 33):
Can someone please give us an example in the history of twin engine jet aircraft operations in which both engines were lost due to something other than fuel starvation or ingestion of foreign debris?

TACA and Garuda 737s; Southern DC-9. Those were weather related flameouts with hail, ice and rain. Perhaps that is what you meant by "foreign debris".


User currently offlineAeroWesty From United States of America, joined Oct 2004, 20822 posts, RR: 62
Reply 44, posted (1 year 7 months 1 week 2 days 7 hours ago) and read 6323 times:

Quoting lightsaber (Reply 30):
Quoting AeroWesty (Reply 19):

I didn't have a problem flying the first ETOPS flights in the 1980s,

I met test engineers who flew the proving flights.   

Show-off.   

Quoting aaron747 (Reply 37):
Are you referring to having sufficient rudder authority on an aircraft like the 77W when losing one engine at the worst possible time?

Hmm, more like the ability to clear terrain over the Himalayas and the Rockies, etc. I recall discussions regarding keeping altitude and oxygen issues. I peripherally understand the laws of physics, but also understand the law of diminishing returns.



International Homo of Mystery
User currently offline3rdGen From Bahrain, joined Jul 2011, 245 posts, RR: 0
Reply 45, posted (1 year 7 months 1 week 2 days 7 hours ago) and read 6258 times:

Quoting BoeingGuy (Reply 43):
Quoting 3rdGen (Reply 33):
Can someone please give us an example in the history of twin engine jet aircraft operations in which both engines were lost due to something other than fuel starvation or ingestion of foreign debris?

TACA and Garuda 737s; Southern DC-9. Those were weather related flameouts with hail, ice and rain. Perhaps that is what you meant by "foreign debris".

Sure, I am trying to get the point across that there has never been a twin engine jet that has lost both engines due to a mechanical failure. At least I was not aware of an event, that's why I asked.

The point is that aircraft are built fail safe, and questioning ETOPS is just stupid, even with the most accident prone airlines/operators and in the most accident prone regions I have not heard of a dual engine failure due to a mechanical fault.

Quoting r2rho (Reply 42):
But having said that... I don't like the idea of ETOPS 240/330.

Ultimately costs rule and with the introduction of ETOPS330 I don't think that there's anywhere left on the planet that a twin cannot fly (If I'm not mistaken with 330 there might be a black spot in the Southern Pacific? or is that gone as well?) . In anycase, ETOPS180 pretty much covers most of the routes that the majority of Airlines fly and ETOPS240 and 330 are for a select few routes, mainly in the Pacific. And as I said ultimately costs rules, manufacturers are not going to build new more efficient 4 engine jets just to satisfy a tiny market in which ETOPS180 is not sufficient, and so regulators have to introduce ETOPS 240/330 in order to ensure those routes are flown. And of course these same routes cannot justify a 380/747. The A340 is the only "small" widebody that could carry the same pax as a 777 but its already obsolete.


User currently offlinerobsaw From Canada, joined Dec 2008, 243 posts, RR: 0
Reply 46, posted (1 year 7 months 1 week 2 days 7 hours ago) and read 6238 times:

I guess when all except a few of the very largest, longest-range, 4-engine airliners are out of service the ETOPS-phobic will stop flying?

The psychology of fear coupled with the lack of a rational understanding of probability and risk is an amazing thing.


User currently offlineXFSUgimpLB41X From United States of America, joined Aug 2000, 4229 posts, RR: 37
Reply 47, posted (1 year 7 months 1 week 2 days 7 hours ago) and read 6160 times:

Quoting AeroWesty (Reply 44):
Hmm, more like the ability to clear terrain over the Himalayas and the Rockies, etc. I recall discussions regarding keeping altitude and oxygen issues. I peripherally understand the laws of physics, but also understand the law of diminishing returns.

I addressed that in my response to you. En route planning takes into consideration for engine out driftdown regardless of how many engines are installed.

Quoting Stitch (Reply 40):

The 747 (and A340 and A380) is (are) perfectly capable of continuing to their original destination with a single engine out and they are not required to divert to an alternate in such a situation (though the flight crew may choose to do so).

Losing an engine is an emergency situation no matter how many are installed on the aircraft. The BA 744 out of LAX a few years ago was a rare case of attempting to continue on. They had to stop short due to the significant altitude and fuel burn penalties involved with an engine out.



Chicks dig winglets.
User currently offlineRara From Germany, joined Jan 2007, 2170 posts, RR: 2
Reply 48, posted (1 year 7 months 1 week 2 days 4 hours ago) and read 6009 times:

Quoting lightsaber (Reply 35):
But what case would happen that wouldn't have put a quad down?

Well, speculatively I could think of an incident where all engines are harmed by some sort of force - perhaps fuel contamination, volcanic ashes or something we can't yet think of. One engine surges and has be switched off. In such a situation, an ETOPS 330 twin would have to continue on maximum continuous thrust for more than five hours, putting enormous stress on an already damaged engine, whereas a quad could carry on relatively easy-going. If another engine fails, the twin goes down and the quad... well, doesn't go down quite as fast.  

Think of QF32. After their uncontained engine failure, they had a boatload of issues with the aircraft, including the remaining engines. I think they were bloody glad they still had three left, not just one. Now, if that had happened over the ocean somewhere..

Quoting Stitch (Reply 40):
The 747 (and A340 and A380) is (are) perfectly capable of continuing to their original destination with a single engine out and they are not required to divert to an alternate in such a situation (though the flight crew may choose to do so).

I think his question was whether a quad can continue with three engines OUT, not three engines turning. While I don't know the answer, my intuition says it would probably stay afloat for a while. A missed approach would be its end though.



Samson was a biblical tough guy, but his dad Samsonite was even more of a hard case.
User currently offlinegoosebayguy From United Kingdom, joined Sep 2009, 417 posts, RR: 0
Reply 49, posted (1 year 7 months 1 week 2 days 4 hours ago) and read 5998 times:

No doubt one plane will finally lose both engines but how many thousands of flights have made it without incident? The economic benefits are so great that even if one went down nothing would change.

User currently offlinetwiga From Canada, joined Mar 2013, 96 posts, RR: 0
Reply 50, posted (1 year 7 months 1 week 2 days 3 hours ago) and read 5910 times:

Quoting lightsaber (Reply 30):
More than 3.3 million ETOPS twinjets flights have been logged since 1985. Approximately, 125 airline operators perform some 1100 ETOPS flights per day ? over 30,000 flights per month. Performed worldwide, it ranks among the very safest and most reliable of all flight operations.>

Another perspective - prorating to today there would be about 6 million ETOPS twin jet flights and assuming average flight of 5 hours (guess) thats 30 million hours accident free (twin engine failure). If 1,000 people spent an average of 1 hour/ day driving back and forth to work for 40 years that would accumulate 1,000 x 250 days x 40 x 1 = 10 million hours - whats the chances of these being accident free hours? And I believe the safety standard for twin engine failure which is classified as Catastophic is 1:10^9 hrs (1:1 billion) which is 33 times more than the 30 million hrs accumulated to date.


User currently offlinelightsaber From United States of America, joined Jan 2005, 13552 posts, RR: 100
Reply 51, posted (1 year 7 months 1 week 2 days 3 hours ago) and read 5904 times:
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Quoting Rara (Reply 48):
volcanic ashes

I know of quads losing all 4 engines in volcanic ash. Again, it has to be something that would hurt a twin, but not all 4 of a quad.

Quoting twiga (Reply 50):
prorating to today there would be about 6 million ETOPS twin jet flights and assuming average flight of 5 hours (guess) thats 30 million hours accident free (twin engine failure).

The requirement is not 10^9. Its 10^7 for the whole jet to crash, so we're 3X past that!

10^9 has no statistical meaning in flight... 10^8 in aerospace is considered infinite for calculation purposes...

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently offlineXFSUgimpLB41X From United States of America, joined Aug 2000, 4229 posts, RR: 37
Reply 52, posted (1 year 7 months 1 week 2 days 1 hour ago) and read 5709 times:

Quoting Rara (Reply 48):
Well, speculatively I could think of an incident where all engines are harmed by some sort of force - perhaps fuel contamination, volcanic ashes or something we can't yet think of. One engine surges and has be switched off. In such a situation, an ETOPS 330 twin would have to continue on maximum continuous thrust for more than five hours, putting enormous stress on an already damaged engine, whereas a quad could carry on relatively easy-going. If another engine fails, the twin goes down and the quad... well, doesn't go down quite as fast.

In all those cases, no matter how many motors you have, they are all going to be affected. With engine out on a 2,3,4 or however many engine aircraft, you're going to be running at MCT for engine out drift down for however many hours.

Quoting Rara (Reply 48):

I think his question was whether a quad can continue with three engines OUT, not three engines turning. While I don't know the answer, my intuition says it would probably stay afloat for a while. A missed approach would be its end though.

3 engines out on a quad will fly you to the crash site.



Chicks dig winglets.
User currently offlineJHwk From United States of America, joined Jan 2013, 247 posts, RR: 0
Reply 53, posted (1 year 7 months 1 week 2 days 1 hour ago) and read 5656 times:

Quoting lightsaber (Reply 51):
I know of quads losing all 4 engines in volcanic ash. Again, it has to be something that would hurt a twin, but not all 4 of a quad.

I'd look at it from the opposite direction; what can happen to two engines of a quad at the same time (within ETOPS rating anyway), with the airframe still able to continue flying? Seems like a much higher risk.

So, if QF-32 lost engine #1 due to shrapnel from #2, could it have continued flying 3 hours to a diversion airport?


User currently offlinecmf From , joined Dec 1969, posts, RR:
Reply 54, posted (1 year 7 months 1 week 2 days ago) and read 5645 times:

Quoting XFSUgimpLB41X (Reply 13):
when a 747 loses an engine they are doing exactly the same thing as the 777- and typically going to divert as close as possible.

My understanding is that most airlines will continue with one of 4 engines out. As long as they have satisfied that the failure is isolated to that engine.

Quoting Stitch (Reply 20):
The FAA now classifies ETOPS as ExTended OPerationS and now also applies it to three and four engine commercial airliners with the publication of Advisory Circular 120-42B.

Yes, but that is for things such as fire fighting. The engine part is still as before.

Quoting Deltal1011man (Reply 27):
Your life is in so much more danger driving to and from the airport than getting on a 767,777,787,330 etc flying to Europe.

No it isn't.

Quoting lightsaber (Reply 30):
The most dangerous point of your whole journey is crossing a street on the way to/from the airport.

No it isn't.

It is all about how you use (abuse) statistics. Per trip aviation is one of the worst. Per mile aviation is doing very well.

Quoting XFSUgimpLB41X (Reply 47):
They had to stop short due to the significant altitude and fuel burn penalties involved with an engine out.

Nope. Read the report. They landed because they miscalculated the remaining fuel.


User currently onlineKlaus From Germany, joined Jul 2001, 21524 posts, RR: 53
Reply 55, posted (1 year 7 months 1 week 1 day 23 hours ago) and read 5543 times:

Quoting lightsaber (Reply 1):
Why are we still debating ETOPS? Its *proven* safe.

 
Absolutely not!

This is an outright dangerous misrepresentation of safety statistics!

I certainly defer to your superior knowledge of engine technology, but this conclusion is simply and blatantly wrong.

The random happenstance (and that is what it is) of no twin having been brought down by dual ETOPS-relevant engine failures is in no way "proof" of anything and cannot be – statistics simply doesn't work like that.

The only thing the empirical data can do is increasing confidence in the hypothesis that ETOPS was "safe" relative to an assumed accident probability.

Habitual drunks have been known to justify their repeated driving in an inebriated state by the so-far absence of fatal accidents – but is that empirical data in fact "proof" that they're safe to drive in that state? I don't think anyone would agree to that.

Sure, ETOPS makes a gamble on a much higher level – but a gamble it remains, particularly since twins have by now lost most of the advantages ETOPS had introduced but have retained their inferior redundancy relative to modern and well-maintained quads.

Quoting lightsaber (Reply 1):
There is no turning back the clock.

Let's talk again after the first (and eventually likely) ditching of an ETOPS twin. The entire discussion is completely ignoring the psychological impact of passengers looking at the twin they're supposed to board for their transpacific flight and being aware of an ETOPS-related disaster that may already have happened by then. This will be a real situation at some point, unfortunately, and the fallout across the aviation industry could be massive when (unfortunately not if) it hits eventually.

And I must say the thought of having to limp along for hours in a single-engine airliner, knowing my life to depend solely on that single remaining engine not developing a fault gives me the creeps even today.

No offense to the dedication and professionalism of yourself and your colleagues – but you can only provide certain (usually very low) probabilities of engine failures. And probabilities (apart from 0 or 1) unfortunately are not certainties, so please be careful about overselling your point beyond the understandable impulse to counter excessive fear of flying.

Quoting Stitch (Reply 7):
Anything that is likely to bring down a commercial airliner with two engines is probably just as likely to bring down a commercial airliner with three, four or more engines.

 
Probably being the operative point.

When we're talking about independent inflight shutdowns, each additional engine adds several orders of magnitude in distance between myself and a ditching in the ocean. And even with dependent inflight shutdowns, additional redundancy present will still generally dominate the equation.

Quoting airbazar (Reply 11):
And when you lose an engine in a twin, typical procedure is to land at the nearest airport (or quad for that matter).

As far as I'm aware, you're much more flexible in a quad when losing one engine, since you still have multiple propulsion redundancy and just somewhat degraded range which needs to be accounted for. You're not necessarily forced to go for that barely suitable emergency airfield but you can still select a more amenable airport with proper facilities or even proceed to to your regular destination. Given the operational implications and costs connected with diversions of any larger airliners, I'd expect that to figure into the total cost of ownership in the long run as well.

Quoting skipness1E (Reply 16):
Actually the issue is you have not understood the chance you are taking. The ETOPS modern twin is no more of a risk than the remaining ageing B747s or the odd A340. It's actually absurd that with so much flight experience some people still cling to an irrational believe that four engines are safer.

I think this thread represents a significant emotional overshoot in the opposite direction.

Yes, ETOPS has spurred a major improvement of overall aviation security which has likely saved many lives since its introduction.

But even though it has been introduced in order to edge out ever more risk-taking routes for twins, it has also almost equally increased the safety of quads by now – basically nullifying any safety advantage ETOPS twins might have had over lower-standard quads in previous times (or even now at shoddier airlines) and leaving the quads well ahead.

Even if we haven't seen the difference exemplified in an ETOPS-related twin going down so far, the difference still exists. And I know which kind of plane I'd prefer given mostly equal conditions otherwise when embarking on a more remote route.

Quoting csavel (Reply 24):
That just doesn't seem right. If you lose 3 engines on a quad, you've lost 75% of your engine power. If you lose one engine on a twin, you've lost only 50% of your power. Yes, I know that in both situations there is only one engine left, but I'd much rather have that remaining one engine represent half of my engine power as opposed to only 1/4 of my engine power.

In one case your redundancy goes down from 1 to 0 with a known range degradation which is already figured into flight planning.

In the other your redundancy goes down from 3 to 2 with again a known range degradation which is already figured into flight planning.

You would not see me preferring the former situation over the latter.

Quoting SmittyOne (Reply 34):
Would the QANTAS A380 that had the uncontained engine failure have made it home with TWO of her engines failing that catastrophically? The answer to that is debatable, but the question tells me that the issue of safety of oceanic flight vs. number of engines is a bit more complex than more = better.

Of course. There is also a probability of dependent damage which increases with engine count. The additional redundancy will just more than compensate in total given plausible values for the respective probabilities and a still "low" number of engines such as 4.

Quoting goosebayguy (Reply 49):
No doubt one plane will finally lose both engines but how many thousands of flights have made it without incident? The economic benefits are so great that even if one went down nothing would change.

I doubt that the impact of knowing a twin flight actually having lost first one, then hours later also the last engine leading to a crash would leave every last passenger completely unaffected in their future selection of airlines and the gear those use.

Such an impact may be small and/or temporary. But then again, it might not.

And as far as I'm aware, a decently filled A380 still isn't economically (or environmentally) matched by any twin.

I'm not saying ETOPS was a bad idea by itself – it has done a lot of good without a doubt. But redundancy still works and probabilities remain probabilities. And when it's about life or death, I prefer mine healthily stacked in my favour, not hollowed out to the maximum degree just to eke out a few Euro "saved" on the ticket.

Quoting XFSUgimpLB41X (Reply 52):
3 engines out on a quad will fly you to the crash site.

Nonsense, when put like that. Pilots have even landed several aircraft with no engines running at all. Do you want to take a guess what they would have given for one still operational? Or the ones who didn't make it for lack of thrust?

As far as I'm aware all current quads can stay aloft and controllable on a single engine, if not as high and not for as long as on all four. That is still very far removed from a certain crash.

Quoting JHwk (Reply 53):
I'd look at it from the opposite direction; what can happen to two engines of a quad at the same time (within ETOPS rating anyway), with the airframe still able to continue flying? Seems like a much higher risk.

Than having lost all engines on a twin? It sounds like utterly bizarre logic to me that a quad with two engines still running was somehow supposed to be even worse off than a twin definitely having to go down in the ocean or in a desert. I certainly know which one I'd pick.

Inflight shutdowns happen at certain probabilities, and this means that on a twin they can also coincide at the square of the individual probabilities (in not-exactly-arithmetical addition to related causes). The combined probability is very low, but it exists, unfortunately (is >0). Whether this may matter to anyone in particular is debatable, of course.

Quoting JHwk (Reply 53):
So, if QF-32 lost engine #1 due to shrapnel from #2, could it have continued flying 3 hours to a diversion airport?

It would probably have been a major challenge due to the secondary damage beyond just the engines, but there would have been a chance even so – a twin would definitely have had to ditch in the ocean, most likely killing everyone aboard.

I'm increasingly bewildered by the strange and often illogical conclusions derived from ETOPS' popularity. It's certainly a good thing, but its benefits are sometimes wildly overestimated.

Yes, flying has some residual risk.
Also Yes, this residual risk has become rather small, not least due to the increased demands of ETOPS.
But part of this progress on safety has been "spent" on cheaper ticket prices by flying twins even on remote routes instead of actually exploiting it for the safety gains which are actually possible when used with quads. There is still a choice involved here, where we want to set our priorities. Having been lucky so far is not a guarantee for anything, unfortunately.

[Edited 2013-05-23 18:24:21]

User currently offlineaaron747 From Japan, joined Aug 2003, 8299 posts, RR: 26
Reply 56, posted (1 year 7 months 1 week 1 day 23 hours ago) and read 5488 times:

Quoting Klaus (Reply 55):
And I must say the thought of having to limp along for hours in a single-engine airliner, knowing my life to depend solely on that single remaining engine not developing a fault gives me the creeps even today.

Isn't this the same as admitting that the logic filter through which you are viewing this issue is inherently colored by emotion?

Quoting Klaus (Reply 55):
Sure, ETOPS makes a gamble on a much higher level – but a gamble it remains, particularly since twins have by now lost most of the advantages ETOPS had introduced but have retained their inferior redundancy relative to modern and well-maintained quads.

Since when are gambles predicated on known outcomes? As you may recall there was a NW 744 with a serious rudder issue affecting flight control a few years back on a transpacific flight - and had things not gone their way that day, who can say? The logically valid argument presented thus far here, is that all engine reliability figures being equal, potential events threatening flight safety apply to both quads and twins.

Quoting Klaus (Reply 55):
No offense to the dedication and professionalism of yourself and your colleagues – but you can only provide certain (usually very low) probabilities of engine failures.

The insurers seem satisfied enough.

Quoting Klaus (Reply 55):
And probabilities (apart from 0 or 1) unfortunately are not certainties, so please be careful about overselling your point beyond the understandable impulse to counter excessive fear of flying.

I would say its rather the impulse to sell more powerplants, but I could be mistaken  



If you need someone to blame / throw a rock in the air / you'll hit someone guilty
User currently onlineKlaus From Germany, joined Jul 2001, 21524 posts, RR: 53
Reply 57, posted (1 year 7 months 1 week 1 day 22 hours ago) and read 5438 times:

Quoting aaron747 (Reply 56):
Isn't this the same as admitting that the logic filter through which you are viewing this issue is inherently colored by emotion?

No, this particular statement was just personal.

Quoting aaron747 (Reply 56):
Since when are gambles predicated on known outcomes?

They aren't, beyond their operational hypotheses being supported or weakened by such known outcomes.

That it is entirely possible to never get a 6 with your first twenty throws of a proper die still doesn't negate the fact that its probability remains at 1/6th, however. Drawing conclusions from such a low-likelihood but still possible sequence is where one needs to be careful, and that same caveat would also apply to an "ETOPS is absolutely safe because nothing has happened yet!" mis-conclusion.

Quoting aaron747 (Reply 56):
As you may recall there was a NW 744 with a serious rudder issue affecting flight control a few years back on a transpacific flight - and had things not gone their way that day, who can say? The logically valid argument presented thus far here, is that all engine reliability figures being equal, potential events threatening flight safety apply to both quads and twins.

Of course other issues exist as well and many are also important – but they do still coexist with issues related to engine reliability.

If engine issues were already negligible, we wouldn't have to talk about this, but they aren't.

Quoting aaron747 (Reply 56):
The insurers seem satisfied enough.

I wouldn't necessarily entrust my life to someone's judgment who's perceiving it primarily as just a calculatory variable. We all make gambles, but there are some I'd like to pick somewhat differently from the popular "the cheapest possible price is the main priority!" sentiment.

Quoting aaron747 (Reply 56):
I would say its rather the impulse to sell more powerplants, but I could be mistaken

I doubt he gets a commission on every engine sold. Not that I'd begrudge him that.

[Edited 2013-05-23 19:00:26]

[Edited 2013-05-23 19:01:34]

User currently offlineaklrno From United States of America, joined Dec 2010, 990 posts, RR: 0
Reply 58, posted (1 year 7 months 1 week 1 day 22 hours ago) and read 5383 times:

Quoting SmittyOne (Reply 34):
Would the QANTAS A380 that had the uncontained engine failure have made it home with TWO of her engines failing that catastrophically? The answer to that is debatable, but the question tells me that the issue of safety of oceanic flight vs. number of engines is a bit more complex than more = better.
Quoting Rara (Reply 48):
Think of QF32. After their uncontained engine failure, they had a boatload of issues with the aircraft, including the remaining engines. I think they were bloody glad they still had three left, not just one. Now, if that had happened over the ocean somewhere..

When I think of how engines fail, I worry about unconfined failures like on QF32. As stated above, the failure caused a boatload of other problems to the adjacent engine as well as to the wing, and IIRC the fuselage as well. On a twin, an uncontained failure can damage the fuselage, but not likely the other engine. A 4 engine aircraft has twice the likelihood of an uncontained failure, so in some ways is riskier.

I do remember there was a 3 engine aircraft where all 3 failed due to a maintenance error, but the rules (and those rules are reflected in ETOPS rules) were changed to prevent that.

The only time I really think about engine failure is in a Cessna Caravan over the Cook Straight. It's only a 20 minute flight, but all over water and mountains on one engine.


User currently offlineN62NA From United States of America, joined Aug 2003, 4595 posts, RR: 8
Reply 59, posted (1 year 7 months 1 week 1 day 22 hours ago) and read 5371 times:

I agree with most of what you've posted in this topic, but this was a bit puzzling to me:

Quoting lightsaber (Reply 1):
As much as the A310/767/A330/777 opened up the globe... the 787 and A350 will do far more.

As it relates to ETOPS, the first generation twins were the "revolutionary" leap. The 787 and A350 will be an "evolutionary" step and as such will do far less.


User currently offlineaaron747 From Japan, joined Aug 2003, 8299 posts, RR: 26
Reply 60, posted (1 year 7 months 1 week 1 day 22 hours ago) and read 5355 times:

Quoting N62NA (Reply 59):
As it relates to ETOPS, the first generation twins were the "revolutionary" leap. The 787 and A350 will be an "evolutionary" step and as such will do far less.

ETOPS was the revolutionary step operationally. These new generation airliners with incredible performance savings instead represent huge possibilities for marketing.



If you need someone to blame / throw a rock in the air / you'll hit someone guilty
User currently offlineAeroWesty From United States of America, joined Oct 2004, 20822 posts, RR: 62
Reply 61, posted (1 year 7 months 1 week 1 day 21 hours ago) and read 5285 times:

Quoting XFSUgimpLB41X (Reply 47):
I addressed that in my response to you.

Well yes, thanks, however I didn't know it was illegal to answer the man's question which he posed to me.  



International Homo of Mystery
User currently offlineAngMoh From Singapore, joined Nov 2011, 506 posts, RR: 0
Reply 62, posted (1 year 7 months 1 week 1 day 19 hours ago) and read 5187 times:

Quoting Klaus (Reply 55):
But part of this progress on safety has been "spent" on cheaper ticket prices by flying twins even on remote routes instead of actually exploiting it for the safety gains which are actually possible when used with quads. There is still a choice involved here, where we want to set our priorities. Having been lucky so far is not a guarantee for anything, unfortunately.

It is all a matter of risk vs cost. And on a whole, the 99.99% of the population would choose the additional risk of ETOPS over the additional cost more engineers - me being in that 99.99% group. For others, the risk is not worth the cost savings, because everyones perception of acceptable risk is different and subjective. I would fly on a Lockheed Constellation any time above a 777 across the south pole if I have to choose either of the 2, even though the overall risk of a Constellation flight more than a 1000x higher. The only way to reduce the risk to 0 is to eliminate it which is in this case not to travel and use video.

Quoting cmf (Reply 54):
Quoting Deltal1011man (Reply 27):
Your life is in so much more danger driving to and from the airport than getting on a 767,777,787,330 etc flying to Europe.

No it isn't.

Quoting lightsaber (Reply 30):
The most dangerous point of your whole journey is crossing a street on the way to/from the airport.

No it isn't.

It is all about how you use (abuse) statistics. Per trip aviation is one of the worst. Per mile aviation is doing very well.

In my personal opinion you are abusing the statistics here. I understand the point you are making that the two modes of transport can not be compared, but by stating "No it isn't" you imply airline safety is below that of road traffic. If as much effort and money went into car safety as into aviation, there would be a lot less than 32,000 deaths a road a year in the US. The reason it is not happing is that the current risk of travelling by car is perceived to be acceptable and consumers are not willing to spend more on it.


User currently offlinetwiga From Canada, joined Mar 2013, 96 posts, RR: 0
Reply 63, posted (1 year 7 months 1 week 1 day 19 hours ago) and read 5169 times:

Quoting lightsaber (Reply 51):
The requirement is not 10^9. Its 10^7 for the whole jet to crash, so we're 3X past that!

You may well be right, but just to let you know where I was coming from. Assuming the loss of two engines is considered as a Catastrophic failure - defined as extremly improbable, normally with hull loss and multiple fatalaties. According to AC25.1309-1A pg 15 and AC23.1309-1E fig 2, pg 23, Class 1V, a Catastrophic event has a probability of 1:10^9 or less. So 1:10^9 is the max. I could be wrong but that's how I presently see it.

www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2025.1309-1A.pdf
www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2023.1309-1E.pdf

[Edited 2013-05-23 22:03:50]

[Edited 2013-05-23 22:10:41]

User currently offlineaaron747 From Japan, joined Aug 2003, 8299 posts, RR: 26
Reply 64, posted (1 year 7 months 1 week 1 day 19 hours ago) and read 5127 times:

Quoting twiga (Reply 63):
Assuming the loss of two engines is considered as a Catastrophic failure - defined as extremly improbable, normally with hull loss and multiple fatalaties. According to AC25.1309-1A pg 15 and AC23.1309-1E fig 2, pg 23, Class 1V, a Catastrophic event has a probability of 1:10^9 or less. So 1:10^9 is the max. I could be wrong but that's how I presently see it.

I think that's a safe assumption.

Looking at multivariate probability, we can't isolate just multiple engine failures as catastrophic events. Given the totality of catastrophic event possibilities, engine failures are just one of the variable modes that must be assumed. There are individual probabilities for each distinct failure mode, but the important consideration is how catastrophic events factor as group.



If you need someone to blame / throw a rock in the air / you'll hit someone guilty
User currently offlineRara From Germany, joined Jan 2007, 2170 posts, RR: 2
Reply 65, posted (1 year 7 months 1 week 1 day 16 hours ago) and read 5015 times:

Quoting lightsaber (Reply 51):
I know of quads losing all 4 engines in volcanic ash. Again, it has to be something that would hurt a twin, but not all 4 of a quad.

But engines aren't either totally fine or totally gone. They can be damaged, and thus more likely to flame stop working at high power settings. When an engine develops problems on a three- or four-holer, the flightcrew will first reduce its power setting before shutting it down, and if necessary continue the flight with one engine set to, say, half performance.

Quoting XFSUgimpLB41X (Reply 52):
In all those cases, no matter how many motors you have, they are all going to be affected. With engine out on a 2,3,4 or however many engine aircraft, you're going to be running at MCT for engine out drift down for however many hours.

Really? That sounds a little too dramatic. We've various examples of quads continuing happily on three engines, above all the infamous BA flight over the Atlantic (but I'm sure there are many more). I can't imagine they drifted down on MCT for hours. At least the 747 seems to have power reserves enough to fly rather comfortably on three engines.

MCT is pretty demanding for an engine. After all, it's exactly the limit, going beyond which would mean damaging it over a longer period of time.

Quoting Klaus (Reply 55):
not hollowed out to the maximum degree just to eke out a few Euro "saved" on the ticket.

But it's more than that. Without ETOPS, many routes would not be viable. Many of the thinner routes over the Atlantic would not be doable if the airlines were forced to use three or four engine aircraft. Look at the MD-11 - a fine aircraft which can't compete as a passenger plane anymore. In other words, the question isn't whether you save a few Euros from, say, DUS to CUR, the question is whether you go at all.

Quoting aklrno (Reply 58):
When I think of how engines fail, I worry about unconfined failures like on QF32. As stated above, the failure caused a boatload of other problems to the adjacent engine as well as to the wing, and IIRC the fuselage as well. On a twin, an uncontained failure can damage the fuselage, but not likely the other engine. A 4 engine aircraft has twice the likelihood of an uncontained failure, so in some ways is riskier.

Wikipedia (I know) says in the QF32 article that after engine 2 failed, engine 1 and 4 went into "degraded mode" (whatever that is). So it seems the engine on the other side of the aircraft was affected as well.



Samson was a biblical tough guy, but his dad Samsonite was even more of a hard case.
User currently offlineflyingturtle From Switzerland, joined Oct 2011, 2583 posts, RR: 14
Reply 66, posted (1 year 7 months 1 week 1 day 15 hours ago) and read 4990 times:

My proposal:

Two-engined aircraft should be regularly flown on one engine only in order to get a real sense of the dangers involved. And the only true appropriate way of flying is, as everybody knows, with three- or four-holers.  

But I think that engines are run for hours and hours and hours at the testing facilities anyway, and stressed to limits unknown in aviation.


David



Keeping calm is terrorism against those who want to live in fear.
User currently offlinelightsaber From United States of America, joined Jan 2005, 13552 posts, RR: 100
Reply 67, posted (1 year 7 months 1 week 1 day 11 hours ago) and read 4875 times:
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Quoting cmf (Reply 54):
It is all about how you use (abuse) statistics. Per trip aviation is one of the worst. Per mile aviation is doing very well.
Fly the average number of hours and your odds of dying in a plane crash are more than 100 times lower than your odds of being run over by a vehicle, and more than 400 times lower than your odds of being killed riding in a vehicle. Even air warriors are 500% more likely to die in a motor vehicle and 25% more likely to be killed walking.
Per: http://voices.yahoo.com/aviation-safety-odds-1044893.html?cat=16

Flying Western Airlines in Western aircraft is extremely safe. If the risk of life is really that much of a concern, automobile safety is the #1 issue that could be corrected. Frequent fliers are more likely to die as a pedestrian. Ok, maybe not on the way to the airport as I stated, but still...

Flying is incredibly safe and with the electric airplanes getting safer.

Quoting Klaus (Reply 55):
Let's talk again after the first (and eventually likely) ditching of an ETOPS twin.

Ok lets talk. One crashes. We morn. But due to the extremely low number of twin crashes, we move on. The news notes it and then common sense points out how over a thousand other ETOPS flights made it.

And statistically, how much lower is the probability of a quad not making it? I'm simply unable to think of a near miss or crash of a widebody in the last 20 years that wouldn't have been equally bad in a quad, trijet, or twin.

If one thinks of the statistics of manufacturing (lives lost per billion dollars of produced goods), going to twins on that alone probably saved more lives.  
Quoting twiga (Reply 63):
ccording to AC25.1309-1A pg 15 and AC23.1309-1E fig 2, pg 23, Class 1V, a Catastrophic event has a probability of 1:10^9 or less.

Interest. I guess I worked the military side too long.  
Quoting Rara (Reply 65):
But engines aren't either totally fine or totally gone. They can be damaged, and thus more likely to flame stop working at high power settings.

In volcanic ash, they all get smothered. I'm not aware of a volcanic ash case where only one engine went out. But I am aware of several were all in a quad did so.

As to damaged engines, bird strikes/ice happen at low altitude. In a twin, if an engine is damaged, they turn around.

Quoting Rara (Reply 65):
At least the 747 seems to have power reserves enough to fly rather comfortably on three engines.

Once established in cruise, a 747 can divert safely on two engines. One is either close enough to the airport to make it or have burned enough fuel to continue on two very abused engines. A scenario so unlikely I hadn't bothered to discuss it before.

The most likely reasons to lose engine power:
1. ice in the fuel
2. contamination in the fuel

Defects in the engine usually express themselves by end of initial climb (highest stress point on the turbine is climb, not takeoff, and end of climb is the worst).

Quoting Rara (Reply 65):
and thus more likely to flame stop working at high power settings.

err... engines have trouble staying lit at *low* power settings. A quad is at such a low thrust level at late cruise there have been events where pressure waves (large vortices) put out an engine prior to FADACs.

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently offlinelightsaber From United States of America, joined Jan 2005, 13552 posts, RR: 100
Reply 68, posted (1 year 7 months 1 week 1 day 11 hours ago) and read 4862 times:
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Odds of dying:

http://www.nsc.org/news_resources/in...tics/Documents/Injury_Facts_43.pdf

You are almost twice as likely to die choking on food as on an airplane. And 'air and space transport' accidents are highly skewed due to carrier deck fatalities or other military accidents.

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently offlineAngMoh From Singapore, joined Nov 2011, 506 posts, RR: 0
Reply 69, posted (1 year 7 months 1 week 1 day 11 hours ago) and read 4841 times:

Quoting lightsaber (Reply 68):
You are almost twice as likely to die choking on food as on an airplane. And 'air and space transport' accidents are highly skewed due to carrier deck fatalities or other military accidents.

  
How many people die every year of a heart attack while travelling on planes? This is definitely not a rare event.


User currently offlineairbazar From United States of America, joined Sep 2003, 8665 posts, RR: 10
Reply 70, posted (1 year 7 months 1 week 1 day 9 hours ago) and read 4828 times:

Quoting clydenairways (Reply 36):
A bit of a strange thread to be starting in 2013, about 30years too late. It's a bit like starting a thread about:

It's not so much a question over ETOPS. In my case it's a question over the new extended ETOPS. I have no problem flying 99% of the ETOPS routes out there.

But ETOPS240 is relatively new and ETOPS330 is on the horizon. Most of today's ETOPS routes are barely ETOPS180. You can probably count in the palm of one hand, 2 at most, the number of ETOPS180 routes. I can tell you that I would not fly an ETOPS240/330 today if I have an alternative. But that's just me. The idea of waiting 4 hours for the nearest emergency airport due to an engine fire or any other shutdown cause, is not something I ever want to experience.


User currently offlineRara From Germany, joined Jan 2007, 2170 posts, RR: 2
Reply 71, posted (1 year 7 months 1 week 1 day 9 hours ago) and read 4815 times:

Quoting lightsaber (Reply 67):
Flying Western Airlines in Western aircraft is extremely safe. If the risk of life is really that much of a concern, automobile safety is the #1 issue that could be corrected.

Yes, but that's only because people drive far more often than they fly. If people took as many plane trips as they take car trips, aviation would be a significant cause of death. I suppose most people personally know someone who was killed in a car crash. If everybody flew several times a day, you'd know someone who was killed in a plane crash.

Quoting lightsaber (Reply 68):
You are almost twice as likely to die choking on food as on an airplane.

That's because people eat more than they fly.  
Quoting AngMoh (Reply 69):
How many people die every year of a heart attack while travelling on planes?

Again, everybody has a heart. Few people have a plane.

This might make it clear:

http://en.wikipedia.org/wiki/Aviation_safety#Statistics

So if you walk to the airport to catch your plane (I used to be able to do that, living in walking distance from Berlin Tempelhof), you're more likely to die on the plane than on your walk to the airport.



Samson was a biblical tough guy, but his dad Samsonite was even more of a hard case.
User currently offlineRara From Germany, joined Jan 2007, 2170 posts, RR: 2
Reply 72, posted (1 year 7 months 1 week 1 day 8 hours ago) and read 4800 times:

Quoting lightsaber (Reply 67):
In volcanic ash, they all get smothered. I'm not aware of a volcanic ash case where only one engine went out. But I am aware of several were all in a quad did so.

Wikipedia has this, on the article on the British Airways ash cloud flight:

"Although the airspace around Mount Galunggung was closed temporarily after the incident, it was reopened days later. It was only after a Singapore Airlines 747 was forced to shut down three of its engines while flying through the same area nineteen days later (13 July) that Indonesian authorities closed the airspace permanently and rerouted airways to avoid the area; a watch was set up to monitor clouds of ash.[3] Flight 9 was not the first encounter with this eruption — a Garuda DC-9 had encountered ash on 5 April 1982.[8]"


I think our disagreement stems from the fact that argue with past events and I argue with future possibilities. I'm quite aware that in recent aviation history, there seem to have been no occurrences which would have brought a twin down but not a quad. That's why we have ETOPS in the first place.

Still, aviation accidents have a way of happening for the first time. Before BA9, nobody really knew of the danger ashclouds posed towards airliners. At some point, due to a factor we don't yet fully understand, this will affect a twin over the ocean.


This is an interesting read, by the way:


http://www.b737mrg.net/media/engine.pdf

Quoting lightsaber (Reply 67):
Flying Western Airlines in Western aircraft is extremely safe. If the risk of life is really that much of a concern, automobile safety is the #1 issue that could be corrected.

Yes, but that's only because people drive far more often than they fly. If people took as many plane trips as they take car trips, aviation would be a significant cause of death. I suppose most people personally know someone who was killed in a car crash. If everybody flew several times a day, you'd know someone who was killed in a plane crash.

Quoting lightsaber (Reply 68):
You are almost twice as likely to die choking on food as on an airplane.

That's because people eat more than they fly.  
Quoting AngMoh (Reply 69):
How many people die every year of a heart attack while travelling on planes?

Again, everybody has a heart. Few people have a plane.

This might make it clear:

http://en.wikipedia.org/wiki/Aviation_safety#Statistics

So if you walk to the airport to catch your plane (I used to be able to do that, living in walking distance from Berlin Tempelhof), you're more likely to die on the plane than on your walk to the airport.



Samson was a biblical tough guy, but his dad Samsonite was even more of a hard case.
User currently offlineJAAlbert From United States of America, joined Jan 2006, 1626 posts, RR: 1
Reply 73, posted (1 year 7 months 1 week 1 day 5 hours ago) and read 4726 times:

I have often looked out the window at the engine on a long haul flight and marveled at its reliability. They fly 4 and 5 thousand miles at extreme temperatures, sit on the ground for a few hours and then fly back (or onward) day after day. Without incident. It's really astonishing when you think about it. What other machines do we have in our society that perform to such a high standard? The jet engine is a marvel, and as others have stated on this thread, the declining rates of accidents since ETOPS came into fashion shows that the two vs. four debate is based on emotions, not fact. I love my flights on 2 engine planes.

That being said, I love those 4 engine airliners too (and the now rare 3 engine planes) and hope they stick around for many more years!


User currently offlinelightsaber From United States of America, joined Jan 2005, 13552 posts, RR: 100
Reply 74, posted (1 year 7 months 1 week 1 day 4 hours ago) and read 4679 times:
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I can only imagine the threads once the CS100 starts flying TATL...

Twin ETOPs will grow. In particular once the 738MAX or A321NEO goes TATL.    They'll do so by current ETOPs rules. And that will be a very good thing.   

Quoting Rara (Reply 71):
So if you walk to the airport to catch your plane (I used to be able to do that, living in walking distance from Berlin Tempelhof), you're more likely to die on the plane than on your walk to the airport.

I already conceded that.  


But as noted, even an 'air warrior' is much more likely to die driving than flying. Yes, they will spend more hours driving, but more miles flying... I simply do not see the concern.

That isn't to say flying won't get safer. It will! Every decade the chance of dying in a crash drops more than 50%.

I'm simply noting that statistically a twin is as safe as a quad until we get into some odd scenarios. But everything costs money, the best use of that money to save lives is tackling cargo hold fires and keeping ETOPs.

Quoting Rara (Reply 71):
I suppose most people personally know someone who was killed in a car crash. If everybody flew several times a day, you'd know someone who was killed in a plane crash.

I only know of military people who have died in aircraft related accidents and yet I worked flight test, the most dangerous part of flying, for a decade. I know of an F-22 pilot who died testing to see if the plane could open bomb bays while initiating a dive while inverted and didn't pull out of his dive bombing attack in time as well as a T-38 set of pilots who also were practicing diving ground attacks would didn't pull out in time.

But I know scores of multi-million mile frequent fliers and none of them know anyone who has died in an air crash.
I know people who chose to drive cross country and died. Multiple car crashes that were fatal in fact... I know fewer people that have driven cross country than have flown it yet more died driving cross country. Per mile, flying is safer. So look at the stats how you wish, if you are traveling trans-ocean, its almost to the point of flying ETOPs or the QE2.

Risk wise, looking at future events, I don't see a statistically significant advantage of a quad over a twin. Not over DECADES. The most likely way to have a crash is a cargo hold fire, pitot tube/control issue, or a pilot heart attack and that isn't engine dependent.

For the negligible difference in safety, we would do more banning pilots over age 55. Seriously. Heck, I know 40 somethings who have had heart attacks. But banning older pilots isn't worth doing.

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently onlineOpethfan From Canada, joined Dec 2012, 666 posts, RR: 0
Reply 75, posted (1 year 7 months 1 week 1 day 2 hours ago) and read 4572 times:

Quoting lightsaber (Reply 74):

I can only imagine the threads once the CS100 starts flying TATL...

I assume you're being facetious, or I'm just dumb.

The only TATL route I could think of in a CS100 is something like BA's LCY - JFK in the A318, are there any more?


User currently offlineStratofish From Germany, joined Sep 2001, 1055 posts, RR: 5
Reply 76, posted (1 year 7 months 1 week 1 day 2 hours ago) and read 4560 times:

Well, ETOPS IS less safe, it has NOT proven anything and it IS a ticking time bomb that WILL cost many lives in the future, period!

However, there are greater threats to aviation safety and in general flying has become safer and safer indeed.
And no matter if we like it or not (as in my case obviously), it is here to stay and since we are running out of options as seemingly no airline opts for quads anymore, we can just as well put up with it.



The Metro might be the Sub(optimal)way
User currently offlineaaron747 From Japan, joined Aug 2003, 8299 posts, RR: 26
Reply 77, posted (1 year 7 months 1 week 1 day 1 hour ago) and read 4510 times:

Quoting Rara (Reply 71):
So if you walk to the airport to catch your plane (I used to be able to do that, living in walking distance from Berlin Tempelhof), you're more likely to die on the plane than on your walk to the airport.

If you consume sausage, beef, margarine, or hydrogenated oils on a regular basis, or sleep fewer than 6 hours a night on average, you are far more likely to have heart problems. Does that mean people should completely change how they live and we should reduce the availability of such food products??? Seriously, this is the direction that kind of logic is going...

Quoting Stratofish (Reply 76):
Well, ETOPS IS less safe, it has NOT proven anything and it IS a ticking time bomb that WILL cost many lives in the future, period!

This really smacks of histrionics.



If you need someone to blame / throw a rock in the air / you'll hit someone guilty
User currently offlineRara From Germany, joined Jan 2007, 2170 posts, RR: 2
Reply 78, posted (1 year 7 months 1 week 1 day 1 hour ago) and read 4472 times:

Quoting aaron747 (Reply 77):
If you consume sausage, beef, margarine, or hydrogenated oils on a regular basis, or sleep fewer than 6 hours a night on average, you are far more likely to have heart problems. Does that mean people should completely change how they live and we should reduce the availability of such food products??? Seriously, this is the direction that kind of logic is going...

I don't see why? For all intents and purposes, people should keep flying, walking, driving and eating the occasional beefsteak. It's all relatively safe.

I just pointed out that the low accident rates in aviation are based on that fact that few people fly, and those that do typically fly not more than a couple of times per year. Contrary to popular belief, aviation is not a particularly safe form of transport; it just appears so because people rarely use it, and when they do, they usually cover huge distances per trip.



Samson was a biblical tough guy, but his dad Samsonite was even more of a hard case.
User currently offlineflyingturtle From Switzerland, joined Oct 2011, 2583 posts, RR: 14
Reply 79, posted (1 year 7 months 1 week 23 hours ago) and read 4408 times:

Quoting Stratofish (Reply 76):
Well, ETOPS IS less safe, it has NOT proven anything and it IS a ticking time bomb that WILL cost many lives in the future, period!

Actually, *every* regulation improves safety.

If there was a regulation that stipulates that any member of an aircrew be over 15 years old, it will improve safety as 12 year old children will have a much harder time understanding what "stall" means, for example.

ETOPS means that stricter maintenance rules be followed, which improves safety anyway – if the A/C is flying over water does not make a difference in itself. To make a fair comparison, you should compare the number of IFSD/engine failures/injuries/deaths/whatever on routes that are both served by ETOPS-certified and ETOPS-noncertified twins.



And by the way, we have experience with ETOPS-60 since 1953.


David

[Edited 2013-05-24 17:48:09]


Keeping calm is terrorism against those who want to live in fear.
User currently offlineAngMoh From Singapore, joined Nov 2011, 506 posts, RR: 0
Reply 80, posted (1 year 7 months 1 week 23 hours ago) and read 4372 times:

Quoting Rara (Reply 72):
Again, everybody has a heart. Few people have a plane.

I was specifically interested in the number of heart attaches WHILE flying...

Quoting Rara (Reply 72):
This might make it clear:

http://en.wikipedia.org/wiki/Aviation_safety#Statistics

So if you walk to the airport to catch your plane (I used to be able to do that, living in walking distance from Berlin Tempelhof), you're more likely to die on the plane than on your walk to the airport.

And these statistics justify ETOPS. Because the main risk is at takeoff and landing. Once in cruise, serious events are very rare. And even if they happen, I can not remember any in the last 25 years which was a purely technical failure. We have had bombs, crew confusion, suicidal pilots, volcanoes, but no accident of multiple failures by independent systems. Just look at some notable events during cruise:
- Gimli Glider: failure to fuel the plane correctly
- Air Transat Azores incident: fuel leak followed by incorrect response of crew
- BA 777: not during cruise. Failure of both engines was due to the same cause and failure mode
For quad planes:
- TWA 800: electrical sparks in central fuel tank leading to explosion
None of them were independent failures of multiple systems, but one single point of failure which affected the whole system. Safety is all about eliminating these single point failures.

We are discussing ETOPS here which is specifically the time away from the nearest airport - which implies it is applicable during cruise only. The real risk is takeoff and landing. The statistic imply that once you are at cruising altitude, flying is the safest mode of any transport even if it is on 2 engines only.


User currently offlineA346Dude From Canada, joined Nov 2004, 1299 posts, RR: 7
Reply 81, posted (1 year 7 months 1 week 20 hours ago) and read 4285 times:

I'm far more worried about cabin or cargo fire than engine failure when over water. So 2 or 4 engines, doesn't really matter to me.


You know the gear is up and locked when it takes full throttle to taxi to the terminal.
User currently offlinelightsaber From United States of America, joined Jan 2005, 13552 posts, RR: 100
Reply 82, posted (1 year 7 months 1 week 18 hours ago) and read 4219 times:
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Quoting flyingturtle (Reply 79):
And by the way, we have experience with ETOPS-60 since 1953.

  

Quoting Opethfan (Reply 75):
I assume you're being facetious, or I'm just dumb.

Neither on the C-series going TATL. These are all business class configurations possibly with extra fuel in the cargo hold.

Privatair will configure some in all business class for TATL. We had a thread on it:
PrivatAir Orders 5 CSeries + Options, All J-class Config (by shanxz Jan 19 2012 in Civil Aviation)

I was looking for Odyssey's order, but was unable to find confirmation of the order:
http://www.ibtimes.com/odyssey-airli...irways-transatlantic-routes-385506

But, there are a number of undisclosed CS100 orders. What matters is Bombardier is promising the range with amazing short field performance.

I also fully expect future (not at entry into service) high MTOW 738MAX and A321NEO versions capable on 'near-TATL.' (3900nm) It is when, not if. Demand is for point to point traffic with frequency (when possible). On 'trunk routes,' we'll still have gauge (quads) as that is the most economical way to transport individuals on popular routes.

I look forward to see what longer range narrowbodies will do with ETOPs from BOS, PHL, MAN, DUB, and other airports (but those are the ones I envision high ETOPs growth once smaller gauge planes have the range).

I see small narrowbodies with TATL range as excellent hub feeders. If the range permits, BA would be wise to transfer BMI slots to more profitable long haul as with AMS too. Which other hubs participate will all depend on equipment range.

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently offlinesweair From Sweden, joined Nov 2011, 1834 posts, RR: 0
Reply 83, posted (1 year 7 months 1 week 17 hours ago) and read 4172 times:

4 engines 4 long haul..   Most cheesy line ever. But hey I would rather fly in the 748i than in a 77W. LH puts even less people in the 748i than EK does in their 77Ws  

The 77W has on fat disadvantage, engine noise very tiresome for 14 hours, the 748i is whispering compared.


User currently offlineopethfan From Canada, joined Dec 2012, 666 posts, RR: 0
Reply 84, posted (1 year 7 months 1 week 16 hours ago) and read 4131 times:

Quoting lightsaber (Reply 82):

Thank you for an excellent and very informative response. It's greatly appreciated.

I must ask, though, does the CSeries have the range for LHR-JFK?

[Edited 2013-05-25 00:57:21]

User currently offlinelightsaber From United States of America, joined Jan 2005, 13552 posts, RR: 100
Reply 85, posted (1 year 7 months 6 days 7 hours ago) and read 3789 times:
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Quoting sweair (Reply 83):
I would rather fly in the 748i than in a 77W. LH puts even less people in the 748i than EK does in their 77Ws

Now that is a reason to fly 4 engines. Room! But its only a 2-class 77W that has more people than a 3-class 748i. Now, the 748 is a far more luxurious configuration (premium heavy). But only a few cities are suited for a high premium configuration of the 748i.

I do think the 748i has a place in EK's fleet. But obviously they don't as they keep buying 77Ws.

Quoting opethfan (Reply 84):
does the CSeries have the range for LHR-JFK?

Only the CS100 in a reduced payload configuration. While the CS300 was designed for 3100nm range, my rumor mill is quoting higher ranges which I'm skeptical about (3400nm). The CS100 was always quoted as having the same range as the CS300, but that makes no sense for a lighter aircraft with the same fuel volume... add to that further fuel (which I do not know where the volume is coming from, such as cargo hold tanks, so I can only speculate), and we have TATL range.

I see the CS100 *not* being competitive on LHR-LCY due to its costs per J class seat vs. a widebody. It will be regulated to LCY-JFK and a few other select TATL markets that wouldn't support a widebody (either by runway or market demand such as speculate HAM-IAD).

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently offlineCXB77L From Australia, joined Feb 2009, 2695 posts, RR: 5
Reply 86, posted (1 year 7 months 5 days 10 hours ago) and read 3581 times:
AIRLINERS.NET CREW
CHAT OPERATOR

For me, ETOPS is a non-issue. I've flown across the Pacific on the 777 and hadn't given that a second thought. In fact, I deliberately chose the 777 flight when the other available flight was operated by an A340, and I would make exactly the same decision again if I were faced with it now.

Quoting XFSUgimpLB41X (Reply 25):
If you lose more than one engine, it's highly likely whatever knocked those out is going to take out all of the engines regardless of how many are installed on the aircraft.

  

Agreed.

Quoting Klaus (Reply 55):
The random happenstance (and that is what it is) of no twin having been brought down by dual ETOPS-relevant engine failures is in no way "proof" of anything and cannot be – statistics simply doesn't work like that.

Agreed, but ...

Quoting Klaus (Reply 55):
Let's talk again after the first (and eventually likely) ditching of an ETOPS twin. The entire discussion is completely ignoring the psychological impact of passengers looking at the twin they're supposed to board for their transpacific flight and being aware of an ETOPS-related disaster that may already have happened by then. This will be a real situation at some point, unfortunately, and the fallout across the aviation industry could be massive when (unfortunately not if) it hits eventually.

The lack of an ETOPS twin crashing as a result of twin independent engine failures from the inception of ETOPS to the present day does not increase the probability of such an event occurring. Something that has a probability of 1 in 1,000,000 does not automatically mean that the probable event will occur on the recording of the 1,000,001st sample. Probability is not constant, it evolves and is dependent on the number of samples. As Lightsaber has posted elsewhere in this thread, there has been more than 3,300,000 ETOPS flights from 1985 to 2003 without incident, when the minimum targeted crash rate was 1 in 1,000,000 flights.

No, the question is not when it happens, but if, and the probability of such an event occurring is so low as to be negligible.

Yes, some might argue that the risk of it occurring at all is unacceptable, but to them I'd just like to point out that we all take risks every single day, with every decision that we make.

Quoting Klaus (Reply 55):
And even with dependent inflight shutdowns, additional redundancy present will still generally dominate the equation.

Please name an event in which dependent inflight shutdowns have brought down, or would have brought down a twin but not a quad.

Quoting Klaus (Reply 55):
It would probably have been a major challenge due to the secondary damage beyond just the engines, but there would have been a chance even so – a twin would definitely have had to ditch in the ocean, most likely killing everyone aboard.

That is a non-sequitur. It does not follow that damage incurred to secondary systems on QF32 would "definitely" have brought down a twin. The fact of QF32 being able to execute a controlled descent and landing was not as a result of it being operated by a four engined A380, but rather because of the multiple secondary system redundancies that have been built into the aircraft so that it was still controllable despite substantial damage. The damage was confined to the port side of the aircraft.

I have yet to see conclusive evidence that such damage, which did not bring down QF32, would have brought down a twin under the same circumstances. Under the same circumstances on a twin, I submit that the damage would have been confined to the number 1 engine and the port wing, and the associated secondary systems which are housed in the port wing. As on QF32 where flight control surfaces were still operative, a twin would also have been able to execute a controlled decent and land safely.

Quoting Klaus (Reply 57):
Drawing conclusions from such a low-likelihood but still possible sequence is where one needs to be careful, and that same caveat would also apply to an "ETOPS is absolutely safe because nothing has happened yet!" mis-conclusion.

The reverse is also true. Concluding that because nothing has happened yet, something will happen in due course, when in fact it is merely a possibility, is ill-conceived.

Quoting Stratofish (Reply 76):
it IS a ticking time bomb that WILL cost many lives in the future, period!

Please qualify this assertion with facts.



Boeing 777 fanboy
User currently offlinemuralir From United States of America, joined May 2013, 5 posts, RR: 0
Reply 87, posted (1 year 7 months 5 days 8 hours ago) and read 3491 times:

Statistically, ETOPS has certainly proved itself safe. However, I'm concerned about the push of manufacturers to have ETOPS certification at the time of introduction of a new airplane design. If I understand correctly, ETOPS certification was initially supposed to be granted only to a specific airplane model and operator combo (e.g. UA 777) only after a certain number of hours of actual flying after which the operator was able to document and prove the safety and maintenance requirements that were required.

Now Boeing and Airbus are pushing to get ETOPS-180 certification and beyond at the time of induction of a new design. Computer models and design testing are great, but IMHO, they are not a substitute for actual data from the world of practical, day-to-day flying.

Thus we have the fiasco of e.g. the 787 which went from ETOPS-180 to grounded after just a few months of actual flying. I realize ETOPS is strictly only about engine failure, but still, this is a great example of why I believe, regardless of what Boeing / Airbus or the airlines want to have, ETOPS ratings should only be granted after operational statistics from actual operations are collected, rather than purely from design and testing data.

But I wonder if the FAA will bow to the immense pressure being placed on it by manufacturers and airliners to weaken the ETOPS certification process. I guess we'll know depending on whether the 787 retains its ETOPS-180 rating when it starts flying again. Imagine that: an airplane that can instantly go from unsafe to fly anywhere to perfectly safe to fly 3 hours from any airport with no actual operational data to prove it!


User currently offlineb2319 From China, joined Jan 2013, 150 posts, RR: 0
Reply 88, posted (1 year 7 months 5 days 8 hours ago) and read 3490 times:

Quoting warden145 (Reply 10):
I know that others here will ridicule me for this post, but opinions were sought and that's my very strongly held opinion on the subject. For the record, I have gone out of my way and spent hundreds of dollars extra to take an intercontinental flight on a four-engine aircraft because I didn't want to take a chance. Fortunately, courtesy of LH's A380, there's going to be at least one four-engine flight from SFO to Europe for the foreseeable future...

It is with sadness and not ridicule that I greet this post. Part of my job is connected with risk assessment in the developing world. How sad that you take such a stance on something that is unlikely to substantially affect your life, ever.....

Regards

B-2319


User currently offlinelightsaber From United States of America, joined Jan 2005, 13552 posts, RR: 100
Reply 89, posted (1 year 7 months 5 days 4 hours ago) and read 3391 times:
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Quoting muralir (Reply 87):
I'm concerned about the push of manufacturers to have ETOPS certification at the time of introduction of a new airplane design. If I understand correctly, ETOPS certification was initially supposed to be granted only to a specific airplane model and operator combo (e.g. UA 777) only after a certain number of hours of actual flying after which the operator was able to document and prove the safety and maintenance requirements that were required.

But the airline still has to obtain ETOPS certification. The difference is that Boeing and Airbus are now doing thousands of hours of additional flight testing to gain that ETOPs cert at EIS. Thus there are processes and procedures developed with the launch airlines to ensure a safe transition to ETOPS.

For the longest ETOPs, there still must be time in service to gain each additional step.

By allowing ETOPs at EIS, a system that forces the airframes and vendors to better understand their products is now in place. My employer now routinely tests valves that go into aircraft over a hundred thousand cycles at temperature or cold, with contamination (a FAA approved sand and salt bath) with added thermal shock all so the parts meet ETOPS EIS requirements. One can tell the difference between ETOPs and non-ETOPs as there is about a factor of 3X difference in the testing requirements.

It is not just analysis. Is it perfect?    It is the testing. No one is going to pay for that level of testing non-ETOPs as it costs millions per valve extra! It just will not be done. We just found "improvements" in two products during the extended testing. Heck, before the 'defects' would have been ignored as they only effect fuel burn and not safety.    But ETOPS requires the testing, so its done and the first shipsets in customer service will have better valves. In this case, the prototype airframes shall fly with valves that do not meet ETOPs reliability, but so what? If it had been a quad, they would have just flown and problems would have been found in the field. Since the parts would have met their warranted life for non-ETOPs duty, it would just have been added revenue.   

Note: Their is ETOPs regulation and ETOPs applied. Gulfstream started a practice on their ETOPS business jets of requiring certain components to have THREE times the service life of the airframe.    While this increases the cost (and slightly the weight) of the parts, the in-service reliability has improved dramatically. Since Rolls Royce was working on the engines, they saw the benefit and started applying to their engine lines. Pratt picked up on this for PurePower and GE for the LEAP-X too (some parts on the GEnX, but that was a transition engine). They're all doing it as it cuts in-service ETOPs costs.

So there is more than just ETOPs. An airframe/engine that will never see ETOPS won't be developed to the same standards as this adds about $100 million to the engine development costs.

My point is to try and point out the FAA has created an incentive system with ETOPS to produce more reliable aircraft that result in much more strenuous component testing. Take aware the incentive of ETOPS at EIS and we'll go back to the old system as then it would be better not to spend the $100 million in the test labs and instead wait for in service data. Take your pick, only one system will thrive.

Quoting muralir (Reply 87):
e.g. the 787 which went from ETOPS-180 to grounded after just a few months of actual flying.

If the 787 were a quad, it still would have been grounded. If you impose the same rules on quads, I guarantee that would make the A380 the last cigar with wings quad ever launched. Pick a scenario that doesn't apply equally independent of engine count.

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently onlineCOSPN From Northern Mariana Islands, joined Oct 2001, 1661 posts, RR: 0
Reply 90, posted (1 year 7 months 4 days 19 hours ago) and read 3230 times:

PA 6 had 4 engines but ditched in 1956 http://en.wikipedia.org/wiki/Pan_Am_Flight_6 HNL-SFO back in those days the coast guard had a ship waiting "just in case" landed next to Ocean Station " November" all were saved

http://en.wikipedia.org/wiki/File:Pacific_Weather_Ships.jpg

Also there are more places to Land than many people think , Cold Bay CDB, Midway Island MDY, Shemya SYA, Yellowknife YZF, Iwo Jima IWO, Guam (UAM and GUM) , have all been used for Emergency Landings, and are well located for such activities.. so the Pacific is not just "nothing" with SFO/SEA on one end and Japan on the other and Hawaii in the Center..

[Edited 2013-05-27 22:45:32]

User currently offlineflyingturtle From Switzerland, joined Oct 2011, 2583 posts, RR: 14
Reply 91, posted (1 year 7 months 4 days 14 hours ago) and read 3146 times:

Quoting A346Dude (Reply 81):
I'm far more worried about cabin or cargo fire than engine failure when over water. So 2 or 4 engines, doesn't really matter to me.

Great point.  


Maybe there is much nostalgia involved. Speaking of me, I would rather fly in a 707 than in a 737. Quads look so "balanced". They come natural to a traveller. For him, it translates into safety. Remember the Titanic, that had a fourth chimney to ventilate the smoker's saloon. Just for aesthetics.


David



Keeping calm is terrorism against those who want to live in fear.
User currently offlinerobsaw From Canada, joined Dec 2008, 243 posts, RR: 0
Reply 92, posted (1 year 7 months 4 days 2 hours ago) and read 2973 times:

Quoting flyingturtle (Reply 91):
Maybe there is much nostalgia involved. Speaking of me, I would rather fly in a 707 than in a 737. Quads look so "balanced". They come natural to a traveller. For him, it translates into safety. Remember the Titanic, that had a fourth chimney to ventilate the smoker's saloon. Just for aesthetics.

Yes, and the great, black plumes of exhaust smoke behind the early jets were great too!

I hope twins look balanced too; one under each wing is usually pretty good.

The Titanic had stacks not "chimneys". But I think the aesthetic purpose is for a more powerful look. And, on that basis I suggest 8 engines (see the Hughes H-4 Hercules "Spruce Goose"; didn't do so well actually flying though).


User currently offlinestratacruiser From United States of America, joined Dec 2011, 113 posts, RR: 0
Reply 93, posted (1 year 7 months 3 days 21 hours ago) and read 2852 times:

Quoting warden145 (Reply 10):
Fortunately, courtesy of LH's A380, there's going to be at least one four-engine flight from SFO to Europe for the foreseeable future...

Along with 744s between SFO and LHR operated by UA, BA and VS...


User currently onlineCOSPN From Northern Mariana Islands, joined Oct 2001, 1661 posts, RR: 0
Reply 94, posted (1 year 7 months 3 days 18 hours ago) and read 2785 times:

Need to move forward in Time not back to 707 and DC-8's we need to protect the Earth also and Twins do that.

User currently onlineKlaus From Germany, joined Jul 2001, 21524 posts, RR: 53
Reply 95, posted (1 year 6 months 3 weeks 8 hours ago) and read 2403 times:

Quoting CXB77L (Reply 86):
The lack of an ETOPS twin crashing as a result of twin independent engine failures from the inception of ETOPS to the present day does not increase the probability of such an event occurring.

Who said it did?

The issue is that you can assume any singular probability to be as low as you want, but as long as it isn't zero, continued repetition will make the aggregated probability of at least one accident happening overall approach 1. And that is exactly what is going on with ETOPS.

Quoting CXB77L (Reply 86):
No, the question is not when it happens, but if, and the probability of such an event occurring is so low as to be negligible.

No, the "if" is only bounded by a possible cessation of ETOPS flights sometime down the road. As long as those continue, the probability of at least one such accident occurring will continue to rise. You may have a low probability in every single flight, but already a substantially higher, varying probability within each year across all flights and a steadily rising probability overall for as long as ETOPS flights keep being conducted.

The probability of never, ever any ETOPS-related accident happening is progressively approaching zero for as long as ETOPS flights continue.

That is pure, basic statistics.

Quoting CXB77L (Reply 86):
Yes, some might argue that the risk of it occurring at all is unacceptable, but to them I'd just like to point out that we all take risks every single day, with every decision that we make.

And when an accident happens, such decisions will be reviewed. And the decisions contributing to the accident may or may not be viewed in a favourable light at that point.

Quoting CXB77L (Reply 86):
Please name an event in which dependent inflight shutdowns have brought down, or would have brought down a twin but not a quad.

See the point of the as-yet-accident-free driving dunk.

Quoting CXB77L (Reply 86):
That is a non-sequitur. It does not follow that damage incurred to secondary systems on QF32 would "definitely" have brought down a twin.

Nor was that the point. The point was what would have happened if a second engine had failed due to shrapnel from the original blowup.

And in such a case a twin would definitely have gone down while the A380 would still have had a realistic chance of reaching an emergency airfield.

Quoting lightsaber (Reply 89):
If the 787 were a quad, it still would have been grounded. If you impose the same rules on quads, I guarantee that would make the A380 the last cigar with wings quad ever launched.

What's that supposed to mean? I can't follow your line of thinking here at all.


User currently offlinerobsaw From Canada, joined Dec 2008, 243 posts, RR: 0
Reply 96, posted (1 year 6 months 3 weeks 5 hours ago) and read 2303 times:

Quoting Klaus (Reply 95):
The issue is that you can assume any singular probability to be as low as you want, but as long as it isn't zero, continued repetition will make the aggregated probability of at least one accident happening overall approach 1. And that is exactly what is going on with ETOPS.

But we're comparing ETOPS vs 3, 4 or whatever-engined planes, which means that there is inevitably SOME fatal incident going to happen for ANY aircraft type. The question is whether the probability is statistically and significantly different between those types BECAUSE of ETOPS and the answer is NO. So, nothing unique whatsoever is happening with ETOPS that makes it overall riskier to fly on that group of aircraft.

Talk about abusing mathematics.


User currently offlineAwysBSB From Brazil, joined Sep 2005, 566 posts, RR: 0
Reply 97, posted (1 year 6 months 3 weeks 4 hours ago) and read 2234 times:

Quoting lightsaber (Reply 82):

Will it take too long for a manufacturer introduces to WN, U2, FR and to charter airlines a narrow-body that lets them enter the transatlantic market?
I long to see some narrow-body ETOPS from LIS to FOR, NAT and even to ANU.


User currently offlinelightsaber From United States of America, joined Jan 2005, 13552 posts, RR: 100
Reply 98, posted (1 year 6 months 3 weeks 3 hours ago) and read 2156 times:
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Quoting AwysBSB (Reply 97):
Will it take too long for a manufacturer introduces to WN, U2, FR and to charter airlines a narrow-body that lets them enter the transatlantic market?

About 2 years after the range was available. Current ETOPS operators (which might include WN soon...) would be much faster 'off the marks.'

Quoting Klaus (Reply 95):
Quoting lightsaber (Reply 89):
If the 787 were a quad, it still would have been grounded. If you impose the same rules on quads, I guarantee that would make the A380 the last cigar with wings quad ever launched.

What's that supposed to mean? I can't follow your line of thinking here at all.

I was replying to the reasons the 787 was grounded had nothing to do with propulsion and electrical generation redundancy. The 787 could have been a quad and still would have been grounded.

Quoting Klaus (Reply 95):
at least one accident happening overall approach 1. And that is exactly what is going on with ETOPS.

Apply that logic to quads too. Certain failures are more likely in a quad than a twin. e.g., an un-contained engine failure. You're too focused on ETOPs vs. quads. The reality is that the overall risk isn't different for airframes of the size that could be a twin or a quad. Twins have a higher risk of loss of propulsion and power generation. Quads have a higher risk of certain catastrophic failures (higher loaded engines). When it comes down to the probability of losing a twin or a quad, the ETOPs twin is less thanks to improved maintenance standards that are partially, but not completely, applied to quads. e.g., a quad can still dispatch with a flakey generator that would be replaced in a twin. A quad may still dispatch with more than one 'well worn' engine (which is more likely to surge).

There is no safety benefit to a quad anymore. ETOPs maintenance requirements were set up to bring the risk of a twin down to that of a quad and that has been acheived. While ETOPs now partially applies to quads, there are still details that differ that I think should be rationalized (more maintenance for the quads).

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
User currently offlinecmf From , joined Dec 1969, posts, RR:
Reply 99, posted (1 year 6 months 3 weeks 3 hours ago) and read 2123 times:

Quoting Klaus (Reply 95):
That is pure, basic statistics.

Sorry Klaus but you are abusing statistics. It isn't relevant that statistically there will be a crash as some time. What is relevant is how frequent there may be crashes. The same logic is applied to all other parts of aviation as the only way to guarantee no accidents is to stop flying and that will be an even bigger negative than the incredibly sparse crashes we have now.

Anyone who try to make this about ETOPS vs four engines in safety is missing the point. They are both incredibly safe. One reach it with more engines and the other by procedures. It really is 6 of one and half a dozen of the other.


User currently online7BOEING7 From United States of America, joined Oct 2012, 1772 posts, RR: 16
Reply 100, posted (1 year 6 months 3 weeks 2 hours ago) and read 2102 times:

Quoting muralir (Reply 87):
I realize ETOPS is strictly only about engine failure

ETOPS is NOT strictly about engine failure!!!

ETOPS is about engines AND a host of other system redundancies/enhancements. Two running engines will do you very little good on a 330E if you have a cargo fire and the suppression is only good for 120E or an electrical issue without the availability of backup generators (777), APU (737/757/767) or RAT.

Quoting COSPN (Reply 90):
PA 6 had 4 engines but ditched in 1956 http://en.wikipedia.org/wiki/Pan_Am_Flight_6 HNL-SFO back in those days the coast guard had a ship waiting "just in case" landed next to Ocean Station " November" all were saved

The Coast Guard did NOT put ships in the middle of the ocean to wait for airplanes that just might ditch right next to them!!!!

Ocean Station November was one of a number of ships throughout the Pacific and Atlantic Oceans put there to provide primarily weather information -- if a floundering ship or airplane in trouble were to be nearby, so much the luckier for the people on board.

[Edited 2013-06-10 14:41:09]

[Edited 2013-06-10 14:42:13]

User currently offlinehivue From United States of America, joined Feb 2013, 1114 posts, RR: 0
Reply 101, posted (1 year 6 months 2 weeks 6 days 22 hours ago) and read 1980 times:

Quoting Klaus (Reply 95):
No, the "if" is only bounded by a possible cessation of ETOPS flights sometime down the road. As long as those continue, the probability of at least one such accident occurring will continue to rise. You may have a low probability in every single flight, but already a substantially higher, varying probability within each year across all flights and a steadily rising probability overall for as long as ETOPS flights keep being conducted.

This is a very common misunderstanding of probability theory. ETOPS operations are designed and certified so that ETOPS flights are independent events and so no ETOPS flight has any effect on the probabilities associated with any other ETOPS flight. There may be an ETOPS related accident some day but the probabilities involved will be only the probabilities associated with that flight and will be unrelated to any previous flight(s).

Quoting Klaus (Reply 95):
The probability of never, ever any ETOPS-related accident happening is progressively approaching zero for as long as ETOPS flights continue.

No. The probability of there "never, ever" being an ETOPS related accident given an unlimited ETOPS lifetime was as close to zero as you can get at the first ETOPS flight and remains at that value today.

Quoting Klaus (Reply 95):
That is pure, basic statistics.

You might want to consult a statistician on that.  


User currently offlinelightsaber From United States of America, joined Jan 2005, 13552 posts, RR: 100
Reply 102, posted (1 year 6 months 2 weeks 6 days 22 hours ago) and read 1949 times:
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Quoting cmf (Reply 99):
Anyone who try to make this about ETOPS vs four engines in safety is missing the point. They are both incredibly safe. One reach it with more engines and the other by procedures. It really is 6 of one and half a dozen of the other.

To some extent I agree. However, right now the procedures are ahead of the redundant propulsion units... more of twin ETOPS needs to go into quad ETOPs. But otherwise, they are very similar in safety.

Ironically, I prefer twins, but every time I shop for a TATL fare, the quads are cheaper (for similar service). Then again, I fly out of LAX, so there is quite a bit of competition...

Quoting hivue (Reply 101):
The probability of there "never, ever" being an ETOPS related accident given an unlimited ETOPS lifetime was as close to zero as you can get at the first ETOPS flight and remains at that value today.

Nitpick, the probability of a problem is going down thanks to improved technology.

Lightsaber



Societies that achieve a critical mass of ideas achieve self sustaining growth; others stagnate.
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