Oceanic Long Haul - 2 or 4?

[411A]

The two engine long haul ops will continue to replace 4-engine types on many routes. This is clearly evident from developments so far.

4 engines, for all but a very few ops...are dead as a doornail.

Except...possibly freight, and even then, as two engine freighters become cost effective in the future, freighters will become twins.

Just the way it is...like it or not.
The only exception is the MD11, but not all that many of those are available.

[SawThe Light]

Not while I've got a Pound (or Euro) or two in my pocket. Give me four engines every time. The only reason I travel with 4 is there is none around (going where I go) with 6.

Long live the 747 and 340 and 380.


STL

[Rollingthunder]

Done lots of trans-atlantic on Stratocruisers, B763s, 2s, 742s, 744s, 340s, 330s.
Done trans-pacific on DC8-43s. 63s, B707s, 747s.
Slightly concerned about B738s west coast NA to Fiji, especially midway between Hawaii and Nandi. Anyway, nevermind.

What are your thoughts on 2 or 4 engines and the comfort level over the vast stretches of the Pacific?

Amelia, you there?

[411A]

Have operated transPacific with three and four engine jets, and the DC6B and 1649A.

Early types had 4 engines because they needed 'em, such was the reliability...and power requirements.

Don't see how the 4 engine types will survive such is the economics/reliability of twins.

Take the route SFO-HNL for example.
No off-route diversion airfields available...and yet the only type to get a wet footprint on that route was a Stratocruiser (lost two)...a very long time ago.
All survived as it ditched alongside OS November.

[SawThe Light]

RT,

The answer to this question might simply relate to the comfort level in the cockpit when you are OEI.

Now, speaking strictly for myself, if I have one shut down I sure feel a deal more comfortable knowing there's 3 out there still churning away.

Give me 4 any day.


STL

[turbynetrip]

I fly with 4 now, but I'd happily take a well-maintained twin over a badly-kept-up 4... though fortunately that's not a problem at our outfit.

It IS nice to be able to keep going to destination should one out of 4 decide to quit, though.

TT

[Wino]

It aint the engines or lack of em that are gonna put you in the drink.

Its fire, or fuel, and fire controll on ETOPS is required to be better than on the quad jets (though many of them have been brought up to similar standards, but not all of em). cargo fire protection is required on etops twins.

Cheers
Wino

[sevenforeseven]

Four engines for longhaul, never a truer word said.

[BlueDog]

Why, with the reliability of modern turbofan engines & ETOPS operations, should "4 engines 4 longhaul" (like the Virgin fallacy displayed on its hulls) be any better?

Before replying emotively I think we should look at the statistics. Have any modern longhaul twin-engine airliners had a double-engine failure? I don't mean those due to fuel starvation, this is just as likely to happen to a four-or-more engined machine.

If anyone can quote some figures that would be great!

[Human Factor]

"4 engines 4 longhaul"

I thought the Bearded One was looking into acquiring the Triple as well.... :E

[Intruder]

It aint the engines or lack of em that are gonna put you in the drink.

True, unless you lose too many of them... If you start with 4, you can afford to lose 1, and can keep it flying with 2. If you start with less, you can afford to lose less...

However, 4 engines also bring 4 generators, 4 separate full-time hydraulic systems, 4 sources of bleed air for pressurization... Loss of any one of those is usually not a big deal, and loss of 2 is controllable. Again, start with less, and you can afford to lose less...

[topoftheloop]

BlueDog

good at theory of probabilities ?

If one aircraft has two engine failures within three days (not the
same engine), how many more flights will you probably have until
one aircraft has two engine failures within 207 minutes ?
(BTW how many flights exceeded their ETOPS limits until today ?)

It is absolutely scandalous to calculate the life of a passenger
against the operational cost difference between a two and a
four engine airplane.
I cannot believe that so many of my professional colleages
accept the decisions of their bean counting management.
Would it be me alone, no worries, I d fly on a single engine
biplane across the globe but dont we have a responsibility
for our passengers to make their journey as safe as possible ?
Sooner or hopefully later we will have the answer.

[Tallbloke]

As I have just written my thesis on the future of long range operations...Wino has it right IMO, the principle issues are not related to engine reliability. Double engine failure from independent causes is highly unlikely, whereas common cause failures are a) more frequent and b) just as likely to occur aboard a twin as a 3 or 4 engine a/c.

What I find concerning is the push by manufacturers for diversion times " to the limit of the aircraft's most time limited system" LROPS, as proposed by Airbus, might allow for direct flight over Antarctica from South America to South Africa and Australasia. Such flights would involve diversion times up to 8 hours (apparently). Anyone fancy flying 8 hours with a cargo fire?

There are also the usual arguments surrounding "adequate" and "suitable" diversion airfields etc. but the upshot is that the number of engines is less important than it used to be.

HOWEVER..ETOPS and it's succesors (which will probably be called ETOPS btw) should have safety as the primary driver. ETOPS207 in the North Pacific is (IMHO) the first time ETOPS was extended primarily for economic rather than safety reasons. This sadly has given ammunition to those who claim that the FAA sometimes acts as marketing department for U.S industry. This is a shame as the conclusions of the ARAC ETOPS working group are generally quite sound.

[expedite_climb]

topoftheloop,

It is absolutely scandalous to calculate the life of a passenger...

True, but unfortunately it happens every day. The likes of the NTSB in the states calculate if the cost of a new safety device is worth fitting or not, in terms of how many passenger lives it will save versus the cost of implementation.

This, has, unfortunately been going on for years....

[Sonic Zepplin]

(Airshow conversation with retired United Capt. regarding ETOP's)

Rumer has it that a United 777 had to shut one down last summer over the Pacific.

Apparently cruised beyond ETOP forcing FAA to re-address the time and distance on 1. Can't confirm never heard anything to come of it.

On a related subject. A close friends son works for either P&W or GE running around the world repairing fan blades on BIG THRUST ENGINES. I've been told that the failure rate on the blades have been higher than the past due to their enormous size.

I understand the blades are pitting and wearing at abnormal rates.

I would prefer 4 any day, at least over the Pacific, but as we all know, the airlines would rather save a few dollars and spend less on fuel.
:ok:

[NWSRG]

Every safety related industry now calculates the cost of saving a life.

This should not frighten anyone. Every time you or I get into a car, we are making the decision that we are prepared to accept the risk of a fatal accident (which sadly is all too high). We do the same when we fly.

Unfortunately money is not endless. So in order to properly focus investment, we have to have some reference to what is 'cost-effective'. It sounds gruesome, but we all know that there will never be enough money to make railways, cars, or even aircraft 100% safe. So we need a mechanism to make the best decision possible.

No need to panic...the approach has worked pretty well up to now. And I speak as someone works in an industry which uses the approach.

[con-pilot]

Well I'm sure all of you have heard the old joke.

Two guys sitting in a airport bar.

First guy, "Hey Bob how come you will only fly on 4 engine airplanes?"

Bob, "Because nobody makes 5 engine airliners."

With that in mind, 3 or more for little ole me.

But I have to agree with a lot of points made by Wino.

[Airguitar]

:uhoh:

I would just HATE to lose an engine over the ocean and only have one remaining.
I am sure all the statistics in the world wouldn't be able to wipe the sweat off my brow at the time.

[Kalium Chloride]

Can't remember who it was exactly, but some senior bod at Rolls-Royce was once asked what he thought defined a really safe aircraft.

His reply was something to the effect: "If my co-pilot told me that an engine had failed...and I asked him which engine...and he said 'Number 29 sir'...and then I asked him 'Number 29 on which side?'..."

[cactusbusdrvr]

ETOPS - Engines Turn or People Swim

I've done transpac in a twin a couple of times - every sound is amplified, every gauge is more closely examined.

[GlueBall]

I count four (4) engines on the new A380! :D

[scud_runner]

United did have an engine failure at the PNR of all places so had to keep on truckin' to Hawaii on one engine. They ended up exceeding the ETOPs limit due to 'unforecasted head winds'
Dunno what the FAA did about it all however it would have been a pretty tense trip 3.5 hours on one engine over the Pacific at night!! Bet those blokes were wishing they were in a 747!! They at the moment hold the record for an ETOPS flight which wouldn't be a terribly saught after record to have i'd imagine

[Ignition Override]

Glueball said it before I could.

[18-Wheeler]

I reckon it's time for more three-engined airliners .... again! :)

[Nineiron]

What was the economic argument for putting 4 engines on the BAe146 when everyone else was building 2 engine shorthaul machines at the time (1981)? I can't believe that beancounters didn't dominate that decision.

[Rollingthunder]

Perhaps it went like this...

Ok you can have four but no thrust reversers.

[Tallbloke]

I thought the 146 was designed for STOL operations hence it's rather unconventional (in airliner terms) configuration.

On the subject of the United diversion, I am led to believe that SOP demand that following an engine failure in a twin, the commander must divert to the nominated diversion field which will be less than 3 hours away. However, that 180 minute calculation has been made on the basis that MCT is selected. I wonder how many aircraft commanders will be willing to select MCT on their sole engine knowing that it will be at a high power setting for 3 hours? Since many more engine failures take place at high power settings than low settings, surely the commander will mitigate against this risk by selecting a lower setting and opting for a lower cruise speed?

[lasernigel]

When you combine this topic with the lack of fuel reserves highlighted in the Shock horror Nigel has to wait thread,it makes worrying reading.By my understanding on a twin,one engine out means lower cruise altitude therefore higher fuel consumption,if there were any delays at the final destination due to weather or other factors, it seems that it's only a matter of time until the inevitable happens.

[Pegasus77]

Don't worry too much lasernigel...

The ETOPS discussion is mostly not about the amount of fuel on board, it is about how long you are willing to fly with only one engine left and no other redundancy over the ocean, which is very black and deep at night.

Losing an engine does not automatically mean a higher fuel flow. If you reduce your speed to max range the trip takes longer, but will use less fuel than at a high cruising speed with 2 engines. The effect of a lower cruise altitude is offcourse included in the ETOPS calculation. On top of that, of you reach your (diversion-) destination after two hours of flight with only one engine, you won't have to wait till all the others have left the holding in front of you. I never heard of any ATCO not clearing the runway immediately for an emergncy.

As you are still flying and not on fire or such, you will have some time to discuss to which airport you will fly and check the weather. On top of that, because you need alternate planning minima for your enroute alternates, the weather forecast for those airports has to comply to certain standards, making a diversion to such an airport possible.

P77

[keendog]

If the 2 v 4 engine debate remains sufficiently alive amongst those of you that fly the things why (as 18 wheeler said) have there been no more new 3 engine designs?
Was there anything seriously wrong with the MD11?

Surely a new 3 engine design would satisfy the bean counters and the worriers and not be too much more trouble to conjure up than a new 2 or 4 engine design.

[lasernigel]

Thanks for your input Pegasus,I added 2+2 and obviously got 5!
But,for instance on the proposed San Francisco - Hawaii 737-800 route,how many diverts are there after PNR?Just interested.

[Torquelink]

How nervous would you be? - You're in a twin over the ocean at night, 180 mins from closest diversion. Both engines have been on the airframe since new and therefore have identical hours and cycles. Suddenly, one engine goes twang as a consequence of a previously unsuspected fatigue problem. You shut it down and then there you are - 180 mins from diversion with one engine remaining which, in every respect, is identical to the one that has just failed and, presumably, is just as likely to suffer the same failure. I bet that 180 mins is longer than a lifetime!

[411A]

keendog,

You are not likely to see a three engine design again.
It is rather weight design limited, and a huge compromise over two.
The only real reason the L10 and the DC10 were three engine designs, was that the engine 'technology' was not up to snuff for two.
The TriStar actually began design life as a twin (for a specific request from AA)...and of couse you didn't see any twin-engined TriStars in the AA fleet..RR couldn't produce a big enough engine.

Altho 4 engines are nice to have for long overwater flights, twins win every time on efficiency grounds, so expect to see a lot of 'em on transoceanic routes.

In addition, no matter how many engines you have, if one fails, lower cruise altitudes are guaranteed, at the heavy weights encountered, and additional fuel burn follows in many cases.
Proper planning from the beginning, together with truly sensible enroute alternates are very necessary to keep safety margins adequate.

[bizflyer]

I never (ever) buy tickets on trans-Atlantic flights that use aircraft with anything less than 4 engines. This limits my options in terms of airline or flight, however after reading some of the remarks made by the people who actually fly the things, I feel somewhat vindicated. For those that can waive stat's about twin op's and their reliability, this must seem incredibly irrational. There is no substitute for multiple redundancy, if lightning never strikes twice in the same spot, why do insurers increase your car premium when you make a claim - even if the accident was somebody else’s fault?

[NWSRG]

Forgive the question, but why is a twin more efficient?

I can understand it being cheaper initially, and I imagine it is cheaper to maintain two engines than four, but is there a significant difference in in-flight efficiency?

Why would four smaller engines not be as efficient as two bigger ones? And would the two bigger engines not need to be significantly over-rated (moreso than the four small) in order to cover for a failure on take-off?

[dreamingA380]

multiple engine failures do occur...

http://www.nw.faa.gov/releases/volash.html

We all know this amazing story, but what if this volcanic ash incident happened to a 777 for example?

I totally agree... the more engines the merrier!

[West Coast]

Just how is a 777 safer than the 747 if all engines are snuffed out on both aircraft? Same would happen to a 10 engined plane if it flew through volcanic dust.


Anyone out there have the data for 2 versus 3/4 engine returns? Same of shutdowns. Saw it a few years ago, it showed that the ETOPS redundancy actually produced a safer product. It wasn't Boeing derived data either.

[javelin]

Ask the 3 and 4 holers what happens when they get a decompression in the middle of the ocean. There are several occasions when they will not have enough fuel to reach a suitable div without either shutting engines down or at least throttling back to idle. At least with twin ops, we have that scenario covered in our fuel planning. It is normally the limiting factor and requires us to carry extra fuel to comply with the planning minima.

[scroggs]

In my airline at least (4 engines only - for the moment!), extra fuel required by the decompression scenario is included in the flight plan. We would not have to shut down engines, or slow down (other than as required by the lower level) in order to make our oceanic diversions.

[18-Wheeler]

West Coast - True, if you fly through a volcanic dust cloud there's a good chance that all the engines may quit. But with four engines you have twice the chance that at least one will light up again when you clear it. Remember the BA 747 with Captain Moody all those years ago, they still only got 75% of the engine running after they were well clear of the dust.

javelin - As Scroggs wrote. Our plans cover low-level diversions. It's really only a problem with long over-water flights though, where you have limited options as to where to go.

[View From The Ground]

I am sure that all crew and pax are nervous when an engine is shut down. Wherever that may happen. I suspect that the degree of nervousness can be directly related to (a) How far one is from the airport (b) How many engines the aircraft has. Personally I realise that I cannot totally eliminate risk from my life, and therefore happily cross any ocean on a twin. This does not mean I wouldn't be worried if an engine failure occurred of course, and truth be told more nervous if it was one of two. However on the same basis we could make all kinds of other rules to live our lives... how about three pilots instead of two in case two pilots fall sick? How about having 2000 feet vertical seperation instead of 1000 etc etc etc.
The fact of the matter is that ETOPS has been running for over a decade and has not caused a single crash. There are other factors CFIT, weather, that are more worrying and more deadly...in terms of numbers killed.
As well as the BA incident was there not a KLM 747 that lost all engines temporarily over the US, again because of volcanic dust? Interesting that both these incidents were four engined aircraft but probably co-incidental.

[TAC On]

scud_runner and others. It seems there may be a little lack of understanding of the rules and concept of ETOPS.


The "ETOPS rule" to which you refer is a PLANNING rule. 90/120/180 (and later 207) minutes, is on 1 eng in still air. This is then worked as a distance which is promulgated in the relevant company documentation as a planning distance limit. Once underway, should you draw s hit as trumps, if you are on your ETOPS distance limit, you could well be more than the prescribed time getting to where you now want to go. This is legal.
I don't know of the incident to which you refer, but assuming their PLANNING was done within the applicable distance limit, then no "rule" was broken. Given the charting and documentation that we recieve for an ETOPS operation, it is unlikely that the aircraft was dispatched outside this distance limit.
My company has designated 1200nm for 777 on 180 minutes ETOPS. Given a headwind of (say) 80 knots this would take about 3:45 to get to the ETOPS alternate, in the worst case scenario. Perfectly legal.

As a point of interest, when testing the new 777ER, Boeing test pilots shut down one, somewhere over the Pacific, then ran for 5 hours until arriving at some god forsaken place.

To my colleagues and myself, who are into this stuff on a daily basis, the scarey factor is the cargo fire. Engines and systems on dedicated/purpose built ETOPS aircraft are designed and certified to higher standards of redundancy than those of past aircraft. Also, fortunately fire fighting and suppression have been vastly increased in these design requirements.

WRT to engines, consider this. It is generally accepted that start and takeoff are the two highest stress times for turbine engines. Given that by the very nature of the operation, the ETOPS aircraft will have significantly less cycles than will its short haul sister, should there be any inherent design or maintenance weakness, in a powerplant, it should, logically, show up earlier in the short haul sister.

The bottom line is: If you wish not to embrace the concept and new technology of ETOPS, then don't do it. There are plenty of guys around that have an open enough mind to learn and understand the way things are, and are prepared to ride the train while it passes you by.

TO

[M.Mouse]

Bizflyer,

You may only travel on 4 engine aeroplanes but most passengers aren't even aware of what type of aircraft they are even on!

Out of interest if you booked a 747 to a destination and then, as often happens, a 777 substitution occurs what do you do?

NWSRG

Engines such as those fitted to the 777 are very much more fuel efficient than those fitted to the 747 but the maintenance costs of two engines versus four is also a large part of the equation. This makes the accountants argument for two engine aeroplanes over four unassailable.

If more people were like Bizflyer then ETOPS wouldn't exist and of course nobody would mind paying more for their tickets for the privilege!

[DistantRumble]

From a non-pilot :

There's no diff. in the ticket price really ...

For example from Dublin it can be cheaper to hop to DUB-LHR-JFK and catch a BA 744, or sometimes it's cheaper A330 EI DUB->JFK

I haven't seen ticket prices carry a 4-engine supplement.

... Butting out

[Cap 56]

Hello 411


I believe the A 380 has four

[Torquelink]

Now believe this or not as you want but Airbus (I assume the A340 dept) claim that total engine maintenance cost (temc) on the A340-300 is 10% less than temc on B777-200ER and that temc on an A340-600 is 12% less than that on B777-300ER. They also show fuel burns as being similar or less. Now I presume that Boeing would disagree as would, maybe, Airbus' A330 dept but it does show that the bald assumption that two engines are cheaper than four is not necessarily clear cut.

[bizflyer]

M.Mouse

Good question, it's never happened to me but I take your point and accept many don't know or care what they are bording. I guess being one of those people who do take a keen interest in which type of aircraft I'm flying on, the 'oh I've never flown on a 777!' novelty factor might overcome the 'oh no it's a twin', who knows? I'm not paranoid enough to balk at the gate because of a change of aircraft but that said I do book flights based on aircraft type.

For the record I wasn't trying to suggest that twin's are fundamentally unsafe, more that I have a personal preference regarding the number of engines. My comment is related to market forces than anything else. A number of posters seem to be forecasting the demise of the 4 engine due to economics, particularly across the Atlantic, I personally believe that whilst costs obviously play a huge - most would say the only - role, market forces also contribute, if this wasn't the case we'd never have heard of "4 engines for long haul" and it wouldn't have emblazoned the side of certain aircraft. I think when they painted that on they weren't trying to attract pilots but people like me?

[javelin]

To re iterate the old saying -

If you have 2 engines, it's only half the amount of stuff that can go wrong !

I have been operating East and West for nearly 10 years on 2 engines without ever considering that it may be even slightly more of a risk than with 3 or 4 engines.

I have also done the Air Transat scenario in real time in the simulator which was a very interesting 30 minutes. Believe me, when we touched down (on speed, on the runway markers ) both the F/O, the sim instructor and myself were maxxed out. An extremely valuable excercise.

[Sonic Zepplin]

DISTANT RUMBLE MAKES A GOOD POINT.

WETHER 2 OR 4 THE PRICE IS THE SAME. GOOD FOR PAX'S

AS FAR AS SAFETY, PILOTS IT SEEMS PREFER 4.

[Wino]

Well if we were to look at actual translantic accidents in the last decade. although twins are more than twice as prevelent as 3 and 4 engine aircraft across the atlantic, twice as many multi engine aircraft have crashed.

TWA 747, Swiss Air MD-11 and an egypt air 767.

and putting egypt air isn't fair because the pilot did it on purpose.

Furthermore another twin ran out of gas because of a fuel leak and just barely made it to the azores (bad procedure lead to the loss of the fuel, but the planning for a two engine crossing saved the day)

This points up the problems that are likely to splash an aircraft and none of them have anything to do with engines...

A twin heads across the water with EXTENSIVE planning for a diversion at every step of the way, including weather and winds for enroute diversions. Quads and trijets are not required to have the same level of planning or have nearby diversion airfields, so when something like a fire or fuel leak strikes onboard an aircraft precious seconds can be lost in the planning of the diversion which the twin already had planned.

As we can see it is FAR more likely that something other than an engine failure put the aircraft in actual jeapody and when fire breaks out seconds can matter. The ETOPS program forces more extensive planning for those contingencies.

Just because an airplane might be able to procede to a destination with an engine shut down, doesn't mean that it wouldnt be far better to have a series of diversion airfields along the way. I will trade the extra engines for the extra runways every day of the week.

Cheers
Wino

PS I will let you in a dirty little secret of pilots (I have done dozens of transatlantic flights in command of 2 and 3 engine aircraft) generally 4 engines pay more than 2 engines hence the extensive lobbying by pilots for their airlines to buy 4 engine aircraft.

ad far as distant rumble goes, the MARKET sets the prices. The efficiency of the operation determines the PROFIT the airline makes, and I guarantee a twin is cheaper over the same route.... Hence more profit all other things being equal.

[M.Mouse]

......market forces also contribute, if this wasn't the case we'd never have heard of "4 engines for long haul" and it wouldn't have emblazoned the side of certain aircraft. I think when they painted that on they weren't trying to attract pilots but people like me?

Bizflyer

I believe you are correct, it was another of the RBs rather tacky(in my opinion) attempts to undermine BA.

I would be interested to know if many people understand or care what they were flying on as long as the price is right.

It will also be interesting, if the rumours are correct, when RB starts operating 777s!

[bizflyer]

M. Mouse

All points accepted. For the record two things I've never done, 777 or Virgin (Atlantic), maybe I should accept the inevitable and give both a go, but I still prefer the thought of 4 tins banging around in the breeze rather than two. I'd also divert your attention to another thread which is discussing 2 failures on etops flights for the same airline. Still think I know where I'd rather be.

[Digitalis]

quote:
--------------------------------------------------------------------------------
......market forces also contribute, if this wasn't the case we'd never have heard of "4 engines for long haul" and it wouldn't have emblazoned the side of certain aircraft. I think when they painted that on they weren't trying to attract pilots but people like me?
--------------------------------------------------------------------------------



Bizflyer

I believe you are correct, it was another of the RBs rather tacky(in my opinion) attempts to undermine BA.


Actually, I think this tag-line belongs to Airbus - they used it in their own advertising, and I think (not certain!) that the line only appears on Virgin's 'Buses, not on the 74s. Agreed, it's a bit cheap, but not as tacky as some of the other bon mots on the side of Virgin's aircraft!

Having said that, 4 for me every time!

[nothumbsup]

Hi all!

I have been on twins for a VERY long time. Operated a/c on 2 and 3 hour etops, over rather wide ponds, with closest airport at some 1300nm. But never felt unsafe or ill at ease. The planning is more rigurous than 3/4 engined a/c, and that's a fact! To the best of my knowledge, until now, there has been no ETOPS related (ie loss of engine or critical system whilst being in the ETOPS area of operations, ie more than 1 hour single engine speed from a suitable airfield for the a/c type) loss of hull, be it on narrow or wide body transport category airplanes. The 2 incidents (presumably the Royal Brunai 757 and 767) might have been ETOPS flights, but I understand that one had a problem at TOC... Even with 4 engines, unless doing a very short hop like CDG-LHR, you would turn back anyway. Flap problem: same thing. YOu would not go anywhere far unless for a short hop with loads of fuel, even on 10 engines!

So, one should differentiate between ETOPS planned and dispatched flight that had a problem after t/off v/s ETOPS related incident, ie when the a/c was in the ETOPS area of operations. It is tobe pointed out, though, any inflight engine shutdown adversly affects the airframe-engine combination ETOPS certification, not just for that carrier but potentialy around the world! (Hence, as long as it is possible, some companies reuest their crew to avoid shuttig down the engine inflight, just leave it at idle as long as it doesn't surge/stall/overheat/burn/vibrate excesiively etc) CX, Thai, EK had to review their ETOPS operations due to engine problems on their repsective 777/330 fleets a while back. But once these problems have been put out of the way, ETOPS is very safe. Hence, for ETOPS dispatch, you require adequate airports+more stringent WX criteria (higher minima than normal all Wx operations) within 2 or 3 hrs single-eng speed. On top of that, the fuel planning at dispatch takes into consideration the critical fuel scenario, ie engine failure combined with explosive decompression: hence you are expected to get to the enroute ETOPS airport within 2/3 hours, on 1 eng flying at 10,000' with the actual winds of the day. Now, that is a fair bit of fuel penalty which has to be sometimes carried. Such stringent requirements do not cover 3/4 eng a/c. Hence, loss of 1 engine+depressurisation at the critical point between the nearest airports is not catered for in 3/4 eng operations (except maybe 1 or 2 operators around the world, noone plans that critical fuel scenario on 3/4 engines) - Air Transat 330 incident indeed proved a point that day: a 3/4 engined a/c would not have made it given the same cicumstances.

As to one of the fire scenarios: getting 2 or 3 hrs ETOPS approval requires a cargo hold fire supression time equivalent to the approved ETOPS diversion time+15minutes. Hence, for a 2 hour ETOPS approved a/c, the cargo hold fire suppression would be of 2hrs+15 mins = 135mins. It is 195mins for 3 hour ETOPS approval. Such is not the case with 3/4 engines when you are not guaranteed to have adequate cargo hold fire supression which would "cover" you whilst you are flying to an enroute alternate.

Hence, ETOPS is as safe if not nmaybe safer than 3/4 engine flights, assuming, of course that any ETOPs operated twin has the a/c certification, operator authorisation, adequate ETOPS flight planning and dispatch, special ETOPS training for pilots and engineers, and good good trend monitoring by engineering.

As to the economics, maybe the newer 4 engined a/c are cheaper to operate than twins, then maybe not. That's for company A and company B to prove... Funny that company A started only with twins and now tries to sell the 340 for its 4 engines, whilst company B started with 4 engine a/c for long haul (707 and 747) and now is pushing the largest ever twin forward for LR operations.

The solution to long haul over hostile areas (be it land or water) lies now with the LROPs study group (as in Long Range Operations) which would cover any long haul a/c, irrespective of engine numbers, to satisfy cargo hold fire suppression, critical fuel case scenarios etc... Now, that is the way forward! THAT would make me feel safer, not simply counting the number of dongs under those wings!
:D

[rotornut]

http://www.airbus.com/dynamic/media/press_releases.asp

AIRBUS RECEIVES 180 MINUTE ETOPS APPROVAL FOR A320 FAMILY AIRCRAFT
APRIL 28, 2004


Leading aircraft manufacturer Airbus has received approval for 180-minute extended range twin-engine operations (ETOPS) with its A319, A320 and A321 single-aisle aircraft, including its corporate jet versions.


The approval was granted by the new European Aviation Safety Agency (EASA). Airbus is also in the process of obtaining approval for the latest family member, the A318. This means that, other than some of its very early aircraft, all twin-engine Airbus aircraft will be approved for ETOPS operations up to 180 minutes.


For around 20 years, ETOPS regulations have governed the design and operation of twin-engine aircraft that are flying routes with a trajectory point that is further than 60 minutes away from an adequate airport when flying on a single-engine. Over the years - due to demonstrated systems and engine reliability - the maximum diversion time that can now be granted to an aircraft type has been increased up to 180 minutes.


Airbus, as a manufacturer of the most cost efficient twin-engine aircraft, has been a driving force in promoting ETOPS approvals and operations for twin-engine aircraft. Its first approval for ETOPS was obtained in 1986, soon after original ETOPS regulations came into force. Airbus, which was the first aircraft manufacturer to have a fly-by-wire aircraft ETOPS certified, as well as being the first to introduce ETOPS requirements into its entire product line, has also established methods for accelerated-ETOPS approval. These are used to achieve ETOPS approval from day-one of entry into service.


Its recent approval recognises the significant in-service experience gathered by the A320 Family and the excellent reliability of the CFM and IAE engines. The A320 Family has now accumulated over 31 million flight hours since entry into service and more than ten years worth of 120-minute ETOPS operations worldwide. Currently there are around ten ETOPS approved Airbus A320 Family operators, a figure which excludes A319 ACJ operators.


The leading aircraft manufacturer with the most modern and comprehensive product line on the market, Airbus is a global company with design and manufacturing facilities in France, Germany, the UK and Spain as well as subsidiaries in the US, China and Japan. Headquartered in Toulouse, France, Airbus is an EADS joint company with BAE Systems.

[nothumbsup]

Just one last thing: ESAS has just granted A319/20/21 family 3 hours ETOPS!!! Now we are going places!!!!! One little problem: so much of fuel to carry, so little payload!

[nothumbsup]

Agree completely.:ok:

[scud_runner]

TAC on I don't work for United however I read about that incident in a magazine which said that they had exceeded the ETOPS limit and the FAA were investigating the incident and reviewing the whole ETOPS thing. Not sure what came of it.

[HotDog]

411A, wasn't one of those Stratocruiser ditchings due to the crew falling asleep and going way off course, running out of fuel?

[411A]

Indeed it was, HotDog...you have a very good memory.
NWA departing from HND enroute HNL.
Astro/pressure pattern navigation used, but if you are in the clag at 21,000, not many star shots possible.
The high range radio altimeter would still work of course, but then you are left with only LORAN A...and the 500mb chart you departed with.
Have personally used LORAN on the Pacific, very good coverage was possible ex-HNL eastbound, but next to nil elsewhere.
Pressure pattern nav worked good, provided it was updated with astro or Doppler, unfortunately Doppler was not fitted to many aircraft at the time.
The particular NWA Stratocruiser was well off course, by at least 500 miles.
Not good...:sad:

[Lou Scannon]

A bit more history:

When pilots were first contemplating crossing the English Channel, the preference was always for single engined airplanes as there was only 50% of suffering an engine failure. Single engined performance has improved a tad since then.

There used to be the story of the Pan Am Captain, who, having lost one over the Atlantic eventually arrived in Keflavik. He walked into ops and was greeted with the words:
"Are you the Pan Am A300 Captain"
To which he replied:
"Used to be Son, used to be..."
I understand that he bid back on to the 727 on his return to base.

Wasn't the last ditching of a passenger plane in the Atlantic (excluding ferry flights) the Flying Tigers Connie on a Military Charter in the late fifties?

[Tallbloke]

The ARAC ETOPS working group applied a similar logic when analysing engine reliability requirements for new Extended Operations regulations (to be known as ETOPS to avoid confusion !?!). ARAC decided that in the event of two engines failing a four engined aircraft requires higher engine reliability than a three engined aircraft as it has twice as many engines left which can fail, and that a further engine failure on a quad (ie 1 engine remaining ) is just as likely to result in the aircraft not being able to land as would be the case in a 3 engined aircraft with all three engines failed.

ARAC ETOPS working group was obviously concerned with operations at great distance from a diversion aerodrome. My question is, would a quad with only one engine operating be able to maintain any altitude (no matter how low) or not?

[codpiece face]

I have worked around brand new aircraft that have had an engine change directly after delivery for the very reason of staggered maintenance. In other words two different houred engines, this should answer the question posted previously about something coming from the factory with two potentially flawed engines.

The rules for maintenance on etops aircraft are very strict with regards to staggered maintenance and duplicate inspections etc. I have to say if i where driving the things i would be far more worried of a fire on board than an engine shutdown.

Finally out of all the shutdowns how many are a precaution rather than a neccesity, and how many of you would try and resart one if you suspect problems with the one remaining??

[411A]

Tallbloke,

Dunno about more modern types, but the B707-320B (advanced) certainly could at training weights only.
This was in the course at PanAmerican long ago, and I personally did so in the actual aircraft...number 3 operating at MCT, others at idle thrust.
The altitude was 4000msl. IAS 'round about 230, as I recall, rudder boost ON, of course.

[Weapons_Hot]

Okay, I seem to remember a conversation with a BAe design engineer who worked on the 146 program. He told me that the reason they went with 4 engines was that there wasn't a stage 3 engine developed with the thrust requirement for the wing pylon design, etc. That left them with the AVRO from (I think) the Bradley Fighting vehicle, or some other type of CAV eqpt.

As for the preferred number of engines on an aircraft, the simple rule is: count all the engines, divide it by 2 and the result MUST be a positive interger GREATER than 1. The MD11 meets that immediate requirement.

I understand that Boeing closed the LBA MD11 line down only because it was SERIOUS competition with its 757/767 line. Pity really - go and try to buy a 2nd hand MD11 today; theyr'e not around.

[rotornut]

I understand that Boeing closed the LBA MD11 line down only because it was SERIOUS competition with its 757/767 line

Correct me if I'm wrong, but I seem to recall that the MD11 didn't live up to it's expectations for range and payload. I understand Singapore Airlines cancelled a major order because of this and went with Airbus instead.

[Wino]

MD 11 screwed up AA's plans as well.

Most of that order was terminated as well when the airplane simply wouldn't do what was promised.

Cheers
Wino

[desert_knight]

Why all the fuss about twin engine jets flying over long stretches of water? They've been around for quite some time and proved themselves to be both safe and reliable.

Now if we really want to improve safety how about gettig rid of those REALLY dangerous bits of kit on aircraft.......flightdeck crew! All the reports I read seem to suggest they are the prime cause of accidents :p

[411A]

DL has six MD-11's available...all you need is cash, $500,000 month.
Strings attached, of course....:E

[galaxy flyer]

With tongue in cheek, so many MD-11s (DC-10 was Death Cruiser, MD-11 More Death) having crashed, 'tis a wonder any are available. But, then again, every operator of them, save FedEx, is selling off their fleets. Except for those on US Mil contracts. And FedEx writes one off with frightening regularity.

Always wondred why, after the USAF bought 60 DC-10s, they started falling to earth like leaves in fall. The AF wrote off at least one in a ground fire.

But, this is MDD bashing.

GF

[Irish Steve]

For what it's worth, the comment I have heard from several people is that the MD 11 is not good in strong cross winds, due to all that weight at the back, and the smaller rudder size as a result of the 3rd engine in the middle.

Certainly it was a factor in the one that ran off the runway here in Dublin a while ago.

[Old Smokey]

I see that this topic has been idle for a while, it's time to re-awaken it from a new perspective. I've also done my share of iceberg counting across the North Atlantic and North Pacific, and am on intimate terms with the emptiness of the Indian ocean.

The fore-going discussions seem to relate to the .01% of the time that a modern jet aircraft suffers single or multiple engine failure. I prefer to address here the 99.99% of occasions that I DON'T lose an engine on a particular flight. (The statistics are far better than this, I'm erring on the conservative side).

Accepting that Takeoff at performance limited weight is probably the most critical of all times to suffer engine failure, the 2, 3, and 4 engined aircraft all meet APPROXIMATELY the same performance criteria with 1 engine inoperative (the 3 and 4 engined aircraft do it slightly better, but only slightly. If obstacle limited, they're identical). In short, the 2 engined aricraft achieves minimum performance on 50% of available thrust, the 3 engined on 67% of available thrust, and the 4 engined on 75% of that available. That ends the discussion on the .01% of flights that an engine fails.

If we look at the 99.99% of the time that an engine DOES NOT fail, and restore the thrust lost in the 'minimum performance' discussion, the 2 engine aircraft operates at a 100% surplus of that required, the 3 holer with a 50% surplus, whilst the 4 engined cow waddles about with a mere 33% margin of excess thrust above minimum.

Given that wind shear, terrain avoidance and other 'balls to the wall thrust' situations claim infinetly more lives and hulls than dead-stick ditchings, I'll stick to the aircraft with the greatest thrust reserve to save my neck in these situations, i.e. the modern 2 engined jet transport. (I have to use the word 'infinetly' here because dividing by zero yields infinity).

Yep, I still have some residual propaganda from a 'past life' on 3 and 4 holers whilst I idly count icebergs from my B777 perch.

[Semaphore Sam]

2, 3 or 4 holes, for us the choice is meaningless. We fly 'em, the money-guys buy 'em. The choices aren't ours, just the techniques for safety and comfort (and that's really illusory...we just carry out orders). Now, what'd REALLY be interesting, is a debate on long-haul engine numbers amongst people who matter....Branson, other CEO's of majors, bankers, etc. Then we'd see on what basis these decisions are really made; suppose someone proposed a single-engined ocean-crosser. D'ya think they'd find people to fly 'em? D'ya think Boston priests have uses for little boys?