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The Ongoing Two Engines Vs. Four Debate  
User currently offlineLeelaw From , joined Dec 1969, posts, RR:
Posted (7 years 6 months 2 weeks 1 day ago) and read 10895 times:

From James Wallace's, the Seattle P-I's aerospace reporter, blog:

"Airbus A340 debate: two engines vs. four"

Quote:
Airbus continues to make the argument, in trying to find customers for its slow-selling, four-engine A340, that four-engine jets are safer than those with two engines when it comes to long-haul flights...

http://blog.seattlepi.nwsource.com/aerospace/archives/111378.asp

Wallace asks why Airbus continues to beat the drums on this old debate about two-engine safety? Is anyone still listening?

In this specific instance, perhaps Mr. Leahy believes there are some "fat-cat" buyers of large VIP-luxury aircraft with whom the tenor of the "four engines for long haul" argument still strongly resonates, i.e. they feel "safer" with four engines? Anyone who can afford to purchase a "private" A345 is probably more concerned about satisfying their own personal safety concerns than optimal operating economics. Is it "immoral" and/or "shortsighted" to appeal to such fears/concerns when marketing an aircraft? Interesting.

123 replies: All unread, showing first 25:
 
User currently offlineTinkerBelle From , joined Dec 1969, posts, RR:
Reply 1, posted (7 years 6 months 2 weeks 1 day ago) and read 10862 times:

Kinda stupid that they're still talking about safety being better on a four-engined aircraft than a two. Way to go Leahy, continue stuffing your foot in your mouth. Sometimes I wonder how the hell this guy is such a darn good salesman with the kind of stuff that comes out of his mouth. Will be interesting to see him change his stance when trying to sell the A350.

User currently offline777ER From New Zealand, joined Dec 2003, 12092 posts, RR: 18
Reply 2, posted (7 years 6 months 2 weeks 23 hours ago) and read 10842 times:
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There was an interesting article in todays paper here about this. NZ is now pleased that its investment in 2 engine long haul aircraft (B777 and B787s) will pay off with Boeings ETOPS range. I feel safe flying in a twin engine as I do flying in a quad.

Of topic, but has anything else happened in relation to a post on here a while ago about VS looking at changing its 4 engine slogan?


User currently offlineLeelaw From , joined Dec 1969, posts, RR:
Reply 3, posted (7 years 6 months 2 weeks 23 hours ago) and read 10843 times:

Quoting 777ER (Reply 2):
but has anything else happened in relation to a post on here a while ago about VS looking at changing its 4 engine slogan?

See: "Virgin Atlantic removes Airbus slogan"
http://blog.seattlepi.nwsource.com/aerospace/archives/110431.asp



See also: Virgin Atlantic Might Want To Rethink Its Slogan (by Leelaw Jan 10 2007 in Civil Aviation)

[Edited 2007-02-10 11:26:05]

User currently offlineMariner From New Zealand, joined Nov 2001, 25081 posts, RR: 85
Reply 4, posted (7 years 6 months 2 weeks 23 hours ago) and read 10836 times:
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Quoting TinkerBelle (Reply 1):
Kinda stupid that they're still talking about safety being better on a four-engined aircraft than a two.

I don't see the word "safety" in either the Leahy statement:

"Already doing sterling service on the world's longest airline routes, the Airbus A340-500 has exactly what a VIP customer wants -- a very large and attractive cabin, four-engined freedom for routings over the remotest regions, and the range to fly nonstop to the world,'' Airbus Chief Operating Officer John Leahy said in a statement.

Or the other quoted part of the release:

"Widebody VIP aircraft offer customers both a larger cabin and more range, allowing larger groups to fly even further nonstop in greater comfort and style. And for customers that select a four-engined A340 or A380, there are added benefits. These include the ability to continue to their destination after an engine failure, better take-off performance in hot and high conditions, and the freedom to overfly remote areas free from extended range twin-engine operations (ETOPS) limitations."

I do see the reporter extrapolating, but I don't see how you can blame Mr. Leahy for that.

???

mariner



aeternum nauta
User currently offlinePhilb From Ireland, joined May 1999, 2915 posts, RR: 13
Reply 5, posted (7 years 6 months 2 weeks 23 hours ago) and read 10818 times:

TinkerBelle,

Have you thought about spending 180 minutes with 300 odd other people on a single engined aircraft with possibly just 1 diversion airport in range - and that being in Siberia or a Pacific island where there is a statistical chance that the runway could be blocked by another incident before you get there?

Twins have proved themselves to be far more reliable than most people thought they would be when ETOPS was launched but if you look at the routes on which the A350/B787 are likely to be used they are not the routes where 180 minutes is an absolute requirement to divert to any airport rather than the worst option. That is why they will be used on the Atlantic, Indian Ocean and over parts of Africa and Asia with multiple diversion points but not on the ultra long haul routes with few alternates.

Leahy is a good salesman because he sells great products on their merits.

Use your acumen as a Financial Analyst to analyse Leahy's statements rather than your anti Airbus prejudice and you would realise that in aviation multiple redundancy is a requirement in many instances, not a luxury.

On the basis of your argument no airliner would have more than the minimum systems required to make it fly - something the industry went away from for very good reasons over 70 years ago starting with the B247 and the DC3.


User currently offline777ER From New Zealand, joined Dec 2003, 12092 posts, RR: 18
Reply 6, posted (7 years 6 months 2 weeks 23 hours ago) and read 10807 times:
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Quoting Mariner (Reply 4):
"Already doing sterling service on the world's longest airline routes, the Airbus A340-500 has exactly what a VIP customer wants -- a very large and attractive cabin, four-engined freedom for routings over the remotest regions, and the range to fly nonstop to the world,

"And the extra bonus of paying for more fuel due to our awesome gas loving A340, what else could you want?"

Quoting Leelaw (Reply 3):

Thanks


User currently offlineLeelaw From , joined Dec 1969, posts, RR:
Reply 7, posted (7 years 6 months 2 weeks 23 hours ago) and read 10806 times:

Quoting Mariner (Reply 4):
I do see the reporter extrapolating, but I don't see how you can blame Mr. Leahy for that.

Indeed, however, I think Mr. Wallace would argue that Mr. Leahy's statements are chock full of "code words/phrases" which raise the issue of safety.


User currently offlineMariner From New Zealand, joined Nov 2001, 25081 posts, RR: 85
Reply 8, posted (7 years 6 months 2 weeks 23 hours ago) and read 10804 times:
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Quoting 777ER (Reply 6):
"And the extra bonus of paying for more fuel due to our awesome gas loving A340, what else could you want?"

I don't see where Mr. Leahy said that either, but clearly some customers are happy to do it.

???

mariner



aeternum nauta
User currently offlineRichardPrice From , joined Dec 1969, posts, RR:
Reply 9, posted (7 years 6 months 2 weeks 23 hours ago) and read 10786 times:

Quoting 777ER (Reply 6):
"And the extra bonus of paying for more fuel due to our awesome gas loving A340, what else could you want?"

"Or would you rather pay the extra money to gain and then maintain an ETOPS rating with a single aircraft?"

Remember that ETOPS is still required by many aviation authorities around the world for VIP aircraft, and ETOPS ratings are not automatic or easy to keep, especially for an ultra small fleet.

While ETOPS still rules, a four engined aircraft for this sort of VVIP usage certainly has more merit than a twin, it can be argued.

[Edited 2007-02-10 11:39:00]

User currently offlineBaroque From Australia, joined Apr 2006, 15380 posts, RR: 59
Reply 10, posted (7 years 6 months 2 weeks 23 hours ago) and read 10767 times:

Quoting 777ER (Reply 6):
"And the extra bonus of paying for more fuel due to our awesome gas loving A340, what else could you want?"

I presume you are banning flights by all 747s in favour of 340s? It seems a logical extension of this thought.


User currently offlineKeesje From , joined Dec 1969, posts, RR:
Reply 11, posted (7 years 6 months 2 weeks 23 hours ago) and read 10770 times:

I think the never dying 2 vs 4 discussion is becoming more telling about the ones that continue to bring it up then about the issue itself.


1972, Airbus A300, the first big twin, pioneering long overwater flights.


User currently offlineMariner From New Zealand, joined Nov 2001, 25081 posts, RR: 85
Reply 12, posted (7 years 6 months 2 weeks 23 hours ago) and read 10746 times:
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Quoting Leelaw (Reply 7):
I think Mr. Wallace would argue that Mr. Leahy's statements are chock full of "code words/phrases" which raise the issue of safety.

He can argue what he likes, but I don't know the code - whatever it is, if there is one - so I still fail to see why people dump on Mr. Leahy for what he didn't say.

???

mariner



aeternum nauta
User currently offlineTinkerBelle From , joined Dec 1969, posts, RR:
Reply 13, posted (7 years 6 months 2 weeks 23 hours ago) and read 10741 times:

Quoting Philb (Reply 5):
if you look at the routes on which the A350/B787 are likely to be used they are not the routes where 180 minutes is an absolute requirement to divert to any airport rather than the worst option.

I wouldn't be too sure about that and 'likely' is the key word here.

Quoting Philb (Reply 5):
Use your acumen as a Financial Analyst to analyze Leahy's statements rather than your anti Airbus prejudice

Anti Airbus prejudice??? That's a new title for me I guess but I'm not prejudiced towards airbus. Airbus offers a superb product and what I have against them is their choice officials because most of them utter things only to eat their words later, especially Leahy. You can read all my previous posts and nothing indicates I'm a prejudiced towards Airbus.

Quoting Mariner (Reply 4):
I don't see the word "safety" in either the Leahy statement:

You're right, he didn't but you know very well what he means.  wink 


User currently offlineMariner From New Zealand, joined Nov 2001, 25081 posts, RR: 85
Reply 14, posted (7 years 6 months 2 weeks 23 hours ago) and read 10731 times:
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Quoting TinkerBelle (Reply 13):
You're right, he didn't but you know very well what he means.   

Sorry, I don't know "what he meant" - beyond what he said.

And what he said seems entirely reasonable to me.

???

mariner



aeternum nauta
User currently offlineKC135TopBoom From United States of America, joined Jan 2005, 12134 posts, RR: 51
Reply 15, posted (7 years 6 months 2 weeks 22 hours ago) and read 10682 times:

Hmmm, is Leahy now saying that his A-330 is less safe than the A-340?  praise   scratchchin 

Isn't the A-330 currently Airbus's best selling WB?  duck 


User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3501 posts, RR: 66
Reply 16, posted (7 years 6 months 2 weeks 22 hours ago) and read 10634 times:

Quoting Philb (Reply 5):
but if you look at the routes on which the A350/B787 are likely to be used they are not the routes where 180 minutes is an absolute requirement to divert to any airport rather than the worst option. That is why they will be used on the Atlantic, Indian Ocean and over parts of Africa and Asia with multiple diversion points but not on the ultra long haul routes with few alternates.

What basis do you have for making this statement?

I think that you will see versions of the A350/777/787 used on all airline long range (over 4000 nm) including the ultra long hauls.



Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
User currently offlineJasond From Australia, joined Jul 2009, 23 posts, RR: 0
Reply 17, posted (7 years 6 months 2 weeks 22 hours ago) and read 10606 times:

The 146 was made famous for 4 smaller, very quiet, efficient engines. Uprate that concept to a larger long-haul aircraft. Any two engine design will always suffer for size ultimatly, not range, but size. I think there is still life in 4 engine designs yet. For a large long haul twin aircraft the engines have to be large, look at the GE90's. The equivalent 4 engine design need not be so large and there is the safety factor with two extra power plants.

User currently offlineA3 From Greece, joined Oct 2006, 262 posts, RR: 8
Reply 18, posted (7 years 6 months 2 weeks 22 hours ago) and read 10594 times:

Quoting KC135TopBoom (Reply 15):
Hmmm, is Leahy now saying that his A-330 is less safe than the A-340?

No.
Pls highlight the word safety out of his quoted sentence.....

The feeling of safety is not something that you can rationalize with. (Thats why is a feeling and not a logical resumption) .



Don't spend your money on airlines that don't respect your business.
User currently offlineZeke From Hong Kong, joined Dec 2006, 9002 posts, RR: 75
Reply 19, posted (7 years 6 months 2 weeks 21 hours ago) and read 10546 times:

Quoting 777ER (Reply 2):
There was an interesting article in todays paper here about this. NZ is now pleased that its investment in 2 engine long haul aircraft (B777 and B787s) will pay off with Boeings ETOPS range. I feel safe flying in a twin engine as I do flying in a quad.

With Air NZ in my view it was an issue of "affordable" safety, which is what ETOPS goes back to, an ETOPS twin is not safer than quad, its just been shown to be "statistically safe".

Statistics is based upon probabilities, the chance of a double engine failure on a twin can be as probable as winning the lotto, just about every week someone seems to win lotto.

I have not seen a single statement from anyone to say a 330/767/777 is safer than a 340, just the 340 provides a higher degree of safety which some people are happier with a "statistically safe" twin engine platform.

And for the rich, why not, if you can afford it, go for a trijet like a Falcon 900 or a quad like a Dc8, 707, 747, 340, 380, which is safer, not just "statistically safe".



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3501 posts, RR: 66
Reply 20, posted (7 years 6 months 2 weeks 20 hours ago) and read 10482 times:

Quoting Zeke (Reply 19):
Statistics is based upon probabilities, the chance of a double engine failure on a twin can be as probable as winning the lotto, just about every week someone seems to win lotto.

The regulatory probability of a dual engine failure on an ETOPS twin for a diversion time of more than 180 min. is on the order of one such event in 10 billion flight hours (1 in 10,000,000,000).

http://dmses.dot.gov/docimages/p88/436040.pdf

Are the odds on your lotto that improbable? If so, the tickets sales required to have a winner must be very high.

[Edited 2007-02-10 14:28:21]


Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
User currently offlineZANL188 From United States of America, joined Oct 2006, 3516 posts, RR: 0
Reply 21, posted (7 years 6 months 2 weeks 20 hours ago) and read 10442 times:
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Quoting Zeke (Reply 19):
I have not seen a single statement from anyone to say a 330/767/777 is safer than a 340, just the 340 provides a higher degree of safety which some people are happier with a "statistically safe" twin engine platform.

Those who claim a 4 engine jet is safer always base their argument on the long haul over water case. In which case there has never been a hull loss of an ETOPS twin.

On the other hand they ignore the enhanced takeoff performance of the ETOPs twin over a 4 engine jet, namely the ability to continue a takeoff and climb on only 50% of the installed thrust. In this case there have been a number of 4 engine jet hull loses with all aboard killed: namely EL AL at Amsterdam & E-3 birdstrike incident at Elmendorf and I'm sure there are others.

So I'll give you your statement: A ETOPS twin is safer than a 4 engine long haul jet



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User currently offlineKeesje From , joined Dec 1969, posts, RR:
Reply 22, posted (7 years 6 months 2 weeks 20 hours ago) and read 10407 times:

Quoting ZANL188 (Reply 21):
ETOPS twin is safer than a 4 engine long haul jet

And I´m sure you will further explain this.

Why is a A330 safer then a A340?

I know a carrier maintaining their 4 engined aircraft to the same ETOPS standards as their 2 engined ones.. perhaps an interesting start for your justification (apart from the anecdotal, belly feeling one).


User currently offlinePhilb From Ireland, joined May 1999, 2915 posts, RR: 13
Reply 23, posted (7 years 6 months 2 weeks 20 hours ago) and read 10383 times:

Quoting OldAeroGuy (Reply 16):
What basis do you have for making this statement?

I think that you will see versions of the A350/777/787 used on all airline long range (over 4000 nm) including the ultra long hauls.

What basis do you have for your assertion?.

Look at the airlines which have ordered the two types so far. Look at the size of the various versions and the routes those airlines fly. Then go to http://gc.kls2.com/ and plot some of the ultra long haul routes tjhose airlines fly using the 120 and 180 minute rule delimiters on the page. (You don't have to rely on Great Circle calculations, you can plot dog legs/minimum time tracks using way points)

There are a some routes that can't be flown within the 180 minute rule. There are a great deal more that are outside the 120 minute rule and many between 120 and 180 minutes are sparse on choice of commercially acceptable diversion points which are a factor when allocating types to a route..


User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3501 posts, RR: 66
Reply 24, posted (7 years 6 months 2 weeks 19 hours ago) and read 10371 times:

Quoting ZANL188 (Reply 21):
So I'll give you your statement: A ETOPS twin is safer than a 4 engine long haul jet

Current fleet statistics indicate there is no significant safety difference between Twins and Quads for current generation aircraft.

http://www.boeing.com/news/techissues/pdf/statsum.pdf



Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
25 ZANL188 : I'd be happy to. 4 engine jets are not required by regulation to survive a loss of 50% of installed engine thrust on takeoff & early climb, ETOPs twi
26 ZANL188 : I'm sure your statistics are quite valid and I have no argument with them. On the other hand you have offered no argument to counter the facts of the
27 LHRBlueSkies : Let me just add to this colourful thread, that I would rather fly on a well-maintained twin, than a badly maintained quad. The recent multiple engine
28 RichardPrice : Im pretty sure thats not just a requirement of ETOPs, its a requirement of opearting any twin, ETOPs or not. The El Al crash was not the result of a
29 Post contains links OldAeroGuy : First of all, the 180 min ETOPS limitation is a thing of the past. The whole world will be opening up to ETOPS beyond 180/207. http://dmses.dot.gov/d
30 RichardPrice : I will again reiterate the point I put forward earlier - This thread is based on something Leahy said after the sale of a VVIP quad, and its also bas
31 ZANL188 : Irregardless of the aerodynamic condition of this aircraft, following the loss of thrust from two engines it would not have been able to climb away a
32 Philb : The point is equally valid for many airlines, more so once the 180/207 minute rule is replaced by what in effect will be a fly anywhere on a twin rul
33 Bond007 : Another statistic to remember, is that when you have 4 engines, you are twice as likely to suffer an engine failure than a 2 engine aircraft is. In mo
34 BrianDromey : Becuse this is what salesmen do, they talk s**t. Say you are buying a used car, a late maodel of the previous generation model. Salesman will tell yo
35 Par13del : Philb my question to you then would be why are both OEM's making new generation twin engine a/c for long haul travel without a caveat that they not be
36 Post contains images ZANL188 : Not hard to prove at all. Ask any four engine jet driver what he thinks of his chances of successfully recovering his aircraft after losing two engin
37 Zeke : Welcome to China. That is actually false, tri jets and quads have a higher/better certified takeoff gradient/performance than a twin. FYI a twin comm
38 Philb : My question to you is why does anyone fly, or drive or ride in a car? It's inevitable that there will be fatal accidents, so why travel at all? . Lif
39 Zeke : Not a problem on a 340, loss of two engines at MTOW, I can maintain height at lighter weights with only one engine. With a 330/340, at 7000' would be
40 Par13del : I agree with your reply Philib, I asked the question based on your premise that after the crash, people would not want to fly twin's overwater. Since
41 ZANL188 : If you will read carefully you'll note that I'm not counting the number of engines nor have I stated that a twin can start a takeoff on one engine. W
42 Philb : Par13del, How much people would be influenced by such an accident has been the topic of many aviation think tank discussions over many years. As time
43 ZANL188 : Huh? Which is it MTOW or a "lighter weight"? Your A340 is not certified nor designed to lose all engines on one wing at takeoff and survive. Good luc
44 Philb : I don't think he's saying that at all. The controlability of the aircraft in that accident was compromised beyond retrievability due to major flying
45 ZANL188 : But it didn't come off clean. It took out the other engine. Once that happened the only thing in doubt was the location of the accident.
46 RichardPrice : A two engines out on the same wing situation produces a predictable controllability change, while the El Al crash also sustained wing and aerodynamic
47 Philb : So, in your view, loss of two engines on one wing at low altitude means an inevitable crash?
48 ZANL188 : Sure it's an arguable point. The nature of the design and certification can certainly make one type of aircraft safer than another, it's done all the
49 Dougloid : Yes....let us put this to rest, starting with John Leahy. His mouth is an ever flowing wellspring of discontent and disinformation.
50 BoomBoom : Unless you're a "limousine liberal", who cares more about being a good citizen of the planet, by not wasting fuel.
51 Bond007 : Not sure what you mean by "nope, it never has". Sure a single engine failure on a 4-engine aircraft has meant a diversion or return - it happened onl
52 SSTsomeday : It's my observation that business is completely ruthless in it's desire to compete and kill the competition, and marketing is not exempt from that st
53 Nwarooster : Four engines with be always be safer than two. Engine technology has improved to the point that the reliability of aircraft engine are almost perfect.
54 Okie73 : actually, the only aircraft certified to operate with an engine that size is the 777, which has automatic yaw compensation. In the event of an engine
55 Mariner : I still don't see that negates a thing Mr. Leahy said: "...a very large and attractive cabin, four-engined freedom for routings over the remotest reg
56 RedFlyer : I wouldn't call it immoral, but definitely shortsighted since the rest of their future product line-up will consist of twins only (not counting the W
57 ZANL188 : IMHO Unless aviation authorities change the way aircraft are designed and certified this will never be true. If things continue as they are 4 engine
58 Jbernie : I prefer flying with FIVE engines.... My dad flew on a QF 742 or 743 back in the early 90s I believe which had a 5th engine strapped to one of the win
59 Mariner : And as a writer I have a profound respect for the use of language. Mr. Leahy clearly chose his words very carefully - to celebrate a good sale - but
60 Post contains images Zeke : Well with respect your posts show a total lack of knowledge. "ETOPs twin with a 50% loss" is nothing to do with ETOPS, takeoff performance is purely
61 Ncfc99 : I have question for ZANL188. If an ETOPS twin lost 50% of its thrust by having an engine fall off and damage the wing, thus changing the controlabilit
62 Adria : Well Boeing also criticized Airbus's fly-by-wire system by saying our pilots can override the computer yet they cannot do that on the 773ER any more.
63 Post contains images Bond007 : Please, I'm not arguing FARs or whether it's safe to go ahead with 3 out of 4 engines - only that there are numerous occasions when either SOPs or ot
64 Zeke : That is false see my comments regarding FAR Sec. 121.565 above. This is false, you really need to have a look at FAR 25.100 series , a summary is bel
65 Zeke : The manufacturers of the newer engines (normally the FADEC ones) can look at the probability of an engine failure across all operators for the type,
66 Bond007 : Just for the record, regardless of FARS and SOPs: "the 777 air turnback and diversion rate is about half that of the A340. For the 12-month period, th
67 RichardPrice : Out of interest, whats the rates between the 777 and the A330? Or can you point me to where I can get this information myself?
68 Bond007 : I can't find it again myself now! I did a Google search, and admittedly I think it was a Boeing article, but presumably they weren't lying about the
69 Post contains images RichardPrice : It would be interesting to find those figures independantly, as we all know marketing personel can be 'creative' with statistics to prove anything th
70 Post contains links Zeke : Found the following http://avitop.com/cs/forums/2025/ShowThread.aspx "Boeing also stated that B777 has lower turnback and diversion rate, but the rat
71 Post contains links Keesje : Zeke, thnx for your profesional insights. As I recall the ElAl crew was not fully aware of the condition of the aircraft after 2 engines shut down. I
72 Post contains images Bond007 : Well, highly dubious interpretation there, and both the linked documents no longer exist. I cannot see that the average 777 trip length is 3 hours, b
73 Post contains images David L : Or one of many other airlines. What are the odds of a quad losing thrust from both engines on the same wing during take-off compared to a twin losing
74 RedFlyer : What is false about my comment? FAR 121.565 does not say the aircraft (quad or tri) can continue to its original destination. Unless I'm interpreting
75 Bond007 : Well, I happen to have data for 5,300 B777 flights departing/arriving the USA (including domestic flights), and the average planned flight length is
76 ADiZzy : I beg to ask the question: Why not three engines. Avaiation has become boring becuase all airplanes look so alike these days. We used to atleast have
77 Philb : There are a number of problems with three engines, not the least of which are those regarding the position and weight at the rear end of the aircraft.
78 EBJ1248650 : It sounds like the thing that makes the 4 engine airliner most practical is the fact that on the very long distance routes (some of them at least) th
79 FlyLKU : Prediction: In a decade, except for the A380, Airbus will have an all twin product line.
80 Zeke : Nearest suitable is only for twins, but that still does mean the closest airport by time or distance, if say with a twin I had an engine failure and
81 GlobalVillage : You have to also remember that a quad is "statistically" more likely to have one or more engines fail. Plus, it's most likely that a quad will divert
82 Post contains images Bond007 : I'm not disagreeing (and how could I) - yes, 90% of diversions are non-mechanical. I was purely being anal and saying that statistically anyway, the
83 Zeke : Have look at reply 65 for my reasons why i think that is wrong. QF for example kept on going to SYD last year in a 747, and turned back to SYD just r
84 Post contains links David L : In case Zeke and others don't want to go through the whole thing yet again, you might want to take a look at these discussions with input from severa
85 777ER : I know he didnt say it B747s are more kinder towards fuel then the A340s
86 RedFlyer : You better go back and read your own FAR 121.565, which you are relying on for your argument. It's very specific: "in point of time". No mention is m
87 JAAlbert : I think this is the point -- research shows that planes with two extra power plants aren't any safer. The 4 engine safety argument is based on fallac
88 RedFlyer : Sorry to burst your bubble, but that was ONE incident. Care to reference any others? And the fact that the FAA dropped the matter does not mean they
89 Jasond : Well maybe I should have qualified that with 'perceived' safety factor. For what it's worth I have always felt 'safer' on 4's rather than 2's, person
90 OldAeroGuy : Quoting anecdotal events to prove one design is more safe than another is a fundamentally bad practice. The overall accident statistics don't back up
91 KC135TopBoom : There was one that came close. IIRC, it was an A-330 that ran out of fuel and glided into the Azores a few years ago.
92 Nwarooster : The British Airways 747 that lost an engine on takeoff from LAX was supposed to fly to LHR. The pilot, with British Airways approval, decided to conti
93 OldAeroGuy : The largest customer for the 772LR is Emirates with 10. Prior to that order, they were flying 10 A345's. If commonality was a primary factor and Twin
94 Philb : Emirates, as you are well aware, splits its fleet between Boeing and Airbus. As it happens, if you look at Emirates routes, only Dubai-JFK comes under
95 Post contains links Zeke : from http://en.safetourchina.com/English/news_detail.asp?id=3168 "China s lottery sales in 2006 increased 10.54 billion yuan from the previous year t
96 David L : I suggested reading the threads, not just the thread titles. Read the comments from pilots from other airlines who actually fly quads. 1. They did no
97 Intermodal64 : If we assume for the moment that the difference in safety between 2 and 4 engines is insignificant, when does it make economic sense to operate 4 vs 2
98 Bond007 : So they would have landed at MAN even they didn't have an engine out then?? ...and yes, I checked the linked threads. Jimbo
99 RedFlyer : Sorry, I've got better things to do than to read 350+ posts (in addition to user profiles) and try to figure out the few that supposedly buttress you
100 RichardPrice : They landed at MAN because of two interlinked reasons - 1. heavier headwinds than expected on the crossing 2. confusion on tank crossfeed procedures
101 SSTsomeday : He doesn't say that a twin jet can't fly to the remotet regions of the world. That is an extrapolation - but it isn't what he said.[/quote] I disagre
102 Bond007 : You sound like a politician - the answer to my question is NO. They would not have landed at MAN if they did not have an engine out. #1 is because th
103 RichardPrice : In that case, you also sound like a politician - trying to boil everything down to an absolute answer when theres no absolutes. Anyway, this discussi
104 SSTsomeday : Question authority.
105 Bond007 : There is clearly an absolute answer. They diverted because they made the crossing on 3 engines. No report has ever disputed that fact, so I don't und
106 Leelaw : Of course there isn't, however, if the reader claims to be not sentient and/or discerning enough to identify and comprehend the "code phrase" imbedde
107 Post contains images David L : My view is irrelevant. Are you interested in the views of experienced quad pilots who don't agree with your view (and I'm not saying all quad pilots
108 OldAeroGuy : The last time I looked, the yuan was worth about .13 US$. This means that 81.93 billion yuan is worth 10.65 billion US$, not 105.4 billion US$ as sta
109 Post contains images Bond007 : No, it was a direct result of having an engine out. Being forced to fly at lower altitudes, and having problems with cross-feeding fuel, were directl
110 Post contains images David L : You're right. That was really directed at other posts.
111 RichardPrice : Why was it lucky at all? It would simply have meant a diversion to any one of the other few dozen airports en route instead of MAN. Stop trying to im
112 OldAeroGuy : Forgot one I wanted to comment on. On page 62 of the download (page 1868 of the Federal Register), the engine reliability line in the table shows tha
113 GBan : As far as I know ETOPS does not come automatically with the aircraft, but has to be "achieved" by the company operating the aircraft. The 777 can do
114 Post contains links OldAeroGuy : This no longer true for FAA Part 121 passenger carrying operators. The new ETOPS rules now require Tri and Quad operators who want to fly routes with
115 Post contains images Keesje : If a 4 engined aircraft designed & maintained to the same safety standard as an ETOPS twin engined aircraft (techically / procedural very possible) l
116 GBan : Thanks for this interesting link! Nevertheless, the rules are not the same - quote from your document (page 10): This final rule is applicable to all
117 Bond007 : I wasn't implying anything. It was commented towards the quote ".. they had more fuel available than they thought they had."! With that kind of fuel
118 OldAeroGuy : I didn't say the rules were the same. However, Tri's and Quad's will have greater accountability than in the past. You can't just buy a Quad now and
119 SSTsomeday : Because I don't believe it's prudent to take a "business as usual" attitude when you lose an engine. Yes, my unqualified opinion (and many quad pilot
120 Post contains images Nwarooster : Just one last statement from me about this incident. There would have been a lot of ramifications, both political and otherwise, if this British Airwa
121 RichardPrice : It was infact taken out of context, the quantity of fuel available at diversion allowed the crew to justify a diversion. The event that changed that
122 RichardPrice : Sorry I hope you consider this a placeholder to a reasoned arguement later on, im not capable of sustaining this at that the moment, but i condier yo
123 SSTsomeday : I look forward to hearing your arguments. Goodnight from the West Coast.
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