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A330 X A340 Performance: South Atlantic Crossings  
User currently offlineMAUZAO From Brazil, joined Aug 2012, 24 posts, RR: 0
Posted (2 years 1 month 1 week 2 days 7 hours ago) and read 19815 times:

On a recent review on AF447 loss published on the brazilian site jetsite.com.br, first official and co-pilot on the AF plane mentioned while entering the stormy area: "... é melhor estarem voando em um A330, pois este tem performance superior ao A340" (... that´s better to be flying on an A330, due it´s superior performance than the A-340).

What they meant? I always imagined that the A-340, for being bigger and having 4 engines, had a much better performance than an A-330. And I feel much more confortable, even safer, flying over the stormy South Atlantic, Brazil to Europe, on any A-340 or B-747-400 than on an A-330. Give me a LX , IB, LH or TP A-340 anytime over an CA, AF or JJ A-330 to Europe!!!

Any thoughts? Thanks.

68 replies: All unread, showing first 25:
 
User currently offlineIndependence76 From United States of America, joined Jul 2007, 252 posts, RR: 0
Reply 1, posted (2 years 1 month 1 week 2 days 7 hours ago) and read 19774 times:

I can't entirely answer your question, but it would be ironic if it were true. The A340 program was originally marketed with the tagline of "If you're over the middle of the Pacific, you want to be in the middle of four engines."

(Also, by any chance, does anyone have the high-res version of that 2-page advertisement?)

Here:
http://boeingblogs.com/randy/images/stormy%20seas%20ad.jpg



"In general, pride is at the bottom of all great mistakes." - John Ruskin
User currently offlineseabosdca From United States of America, joined Sep 2007, 5518 posts, RR: 6
Reply 2, posted (2 years 1 month 1 week 2 days 6 hours ago) and read 19614 times:

With all engines working, twins have more excess power than quads. I think that's all he meant.

User currently offlineADent From United States of America, joined Dec 2006, 1387 posts, RR: 2
Reply 3, posted (2 years 1 month 1 week 2 days 4 hours ago) and read 19248 times:

One of the design drivers for engine size is one engine out takeoff at MTOW.

If a plane needs 90,000 of thrust to get off the runway in the case a quad engined plane could use (4) 30,000 thrust engines, because with one engine out you still have 90,000.

On a twin you would need (2) 90,000 thrust engines, so with one engine out you still have 90,000.

So in normal, day-to-day use the quad would have 120,000 thrust available and the twin would have 180,000 thrust (at sea level, but at altitude presumably the ratios would be the same).


User currently offlinejollo From Italy, joined Aug 2011, 226 posts, RR: 0
Reply 4, posted (2 years 1 month 1 week 2 days 1 hour ago) and read 18705 times:

The overall reliability advantage of a 4-holer has nothing to do with thrust margin at cruise.

A340's climb performance at altitude is notoriously sluggish compared to, say, a 777. Of course, that's with all engines running: with one engine out the picture is rather different.


User currently offlinezeke From Hong Kong, joined Dec 2006, 9111 posts, RR: 75
Reply 5, posted (2 years 1 month 1 week 1 day 22 hours ago) and read 18203 times:

Quoting jollo (Reply 4):
A340's climb performance at altitude is notoriously sluggish compared to, say, a 777. Of course, that's with all engines running: with one engine out the picture is rather different.

As far as I am aware, the A340-300 will reach a high initial operating altitude than a 777-200ER at max weight, and a A340-600 will climb about 4000 ft higher than a 777-300ER at max weight.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlinedennys From France, joined May 2001, 889 posts, RR: 1
Reply 6, posted (2 years 1 month 1 week 1 day 18 hours ago) and read 16134 times:

Excuse me , but if i had the choice i would prefer crossing any oceans on a 4 jets aircraft !

User currently offlinethenoflyzone From Canada, joined Jan 2001, 2512 posts, RR: 11
Reply 7, posted (2 years 1 month 1 week 1 day 18 hours ago) and read 15902 times:

Quoting dennys (Reply 6):
Excuse me , but if i had the choice i would prefer crossing any oceans on a 4 jets aircraft !

Sure, but it doesn't necessarily mean you're any safer than on a twin !

Twice the number of engines means twice as many things could go wrong with those engines.

Quoting zeke (Reply 5):
As far as I am aware, the A340-300 will reach a high initial operating altitude than a 777-200ER at max weight, and a A340-600 will climb about 4000 ft higher than a 777-300ER at max weight.

He's talking about climb performance (i.e rate of climb), not initial climb altitude.

Thenoflyzone



us Air Traffic Controllers have a good record, we haven't left one up there yet !!
User currently offlineSemaex From Germany, joined Nov 2009, 823 posts, RR: 2
Reply 8, posted (2 years 1 month 1 week 1 day 17 hours ago) and read 15381 times:

Quoting thenoflyzone (Reply 7):
Twice the number of engines means twice as many things could go wrong with those engines.

Aaah here comes the point that has brought people to the edge of war for centuries  
Often times pilots / airlines / engeneers / pax / enthusiasts argue on what is the better solution. You have the "fail-safe" (redundancy) supporters in the one corner and you have the "damage-tolerant" (over-engeneering) geeks in the other. There are pilots which say that when one engine is out, you're better off still having three instead of one to carry you home. And then there are those who support your view and say "when one engine has a problem, and the other three are the exact same engine, then they might have the same problem". Who's right? I don't know, up to the individual to decide.
You can even extend the discussion onto other airplane structures, for example the school of thought promoting "fly-by-wire". There are those who say that when pullies and levers actuate flight controls, then the more you use those tools the more redundancy the system has, but the likelier it is that one failing component (eg. being stuck) corrupts the whole system.

Interesting topic nontheless, worth thinking about the quad vs. twin performance. It would be great though to know what is meant by "performance", as there are numerous subcategories where, depending on who you ask, a twin is better in the one and a quad better in the other aspect.



// You know you're an aviation enthusiast when you look at your neighbour's cars and think about fleet commonality.
User currently offlineRoseflyer From United States of America, joined Feb 2004, 9661 posts, RR: 52
Reply 9, posted (2 years 1 month 1 week 1 day 17 hours ago) and read 15348 times:

The A332 has more thrust and lower MTOW than the A343 that AF operate. That translates into much better climb performance. The A332 can achieve higher initial cruise altitude than the A343 can when operating near MTOW. However it all depends on the load and weather of a specific flight.


If you have never designed an airplane part before, let the real designers do the work!
User currently offlinetjcab From Canada, joined Oct 2004, 333 posts, RR: 0
Reply 10, posted (2 years 1 month 1 week 1 day 17 hours ago) and read 14763 times:

Quoting thenoflyzone (Reply 7):
Twice the number of engines means twice as many things could go wrong with those engines.

With that logic, then one engine should be the best solution.

Why the need for ETOPS then? If cost was not a factor, I would imagine most would prefer more engines.


User currently offlineseabosdca From United States of America, joined Sep 2007, 5518 posts, RR: 6
Reply 11, posted (2 years 1 month 1 week 1 day 16 hours ago) and read 13908 times:

Quoting tjcab (Reply 10):
With that logic, then one engine should be the best solution.

There is a balance between redundancy and increasing probability of failure as you increase redundancy.

So far, real-world operational history of all types of aircraft seems to indicate that two engines strikes that balance better than any other number, provided the two-engine aircraft is operated to ETOPS standards.


User currently offline135mech From United States of America, joined Oct 2006, 412 posts, RR: 4
Reply 12, posted (2 years 1 month 1 week 1 day 15 hours ago) and read 13625 times:
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My buddy started going to ATC school. One of the things they were instructed upon was that the A342/343 needed extra "time" to get off of the ground due to being underpowered on normal take off with the small CFM's. They were notorious for taking the "full" runway and their climb rates were sluggish at best. The couldn't climb out of cities fast or high enough, so that might be a factor for maneuverability at altitude.

As I said, this was what the ATC school was teaching future air traffic controllers.


User currently offlineAquila3 From Italy, joined Nov 2010, 266 posts, RR: 0
Reply 13, posted (2 years 1 month 1 week 1 day 14 hours ago) and read 13008 times:

Quoting seabosdca (Reply 11):
So far, real-world operational history of all types of aircraft seems to indicate that two engines strikes that balance better than any other number, provided the two-engine aircraft is operated to ETOPS standards.

Respectfully, I beg to disagree.
There is no straight demonstration of that theory that I have seen since now, in mathematical or statistic sense.
First, the demonstration is weak because it is a "reverse" demonstration (A twin did not have a double independent engine failure so it is absolutely reliable), then the sample base is too small for both cases (independent multiple engine failures).
I suspect that the choice of ETOPS (to clarify what I mean: to authorize twins to cross large extents of water) was driven only by economics, and I better I do not go too in deep on how the may have worked.
So, in absence of straight theories I stay with my common sense. Better four than two, God forbids one.



chi vola vale chi vale vola chi non vola è un vile
User currently offlinezeke From Hong Kong, joined Dec 2006, 9111 posts, RR: 75
Reply 14, posted (2 years 1 month 1 week 1 day 14 hours ago) and read 12830 times:

Quoting thenoflyzone (Reply 7):

He's talking about climb performance (i.e rate of climb), not initial climb altitude.

That is not how I was reading the OP, getting to altitude to get over weather.

Quoting Roseflyer (Reply 9):
The A332 can achieve higher initial cruise altitude than the A343 can when operating near MTOW.

When the A330 and A340 are operated over the same route, with the same payload, the climb altitude would be the same, same wing. At MTOW the A340 is less than an A330 at MTOW, because it is 40+ tonnes heavier, nothing to do with the engine, it is still higher than a 777 at MTOW.

Quoting 135mech (Reply 12):
My buddy started going to ATC school. One of the things they were instructed upon was that the A342/343 needed extra "time" to get off of the ground due to being underpowered on normal take off with the small CFM's. They were notorious for taking the "full" runway and their climb rates were sluggish at best. The couldn't climb out of cities fast or high enough, so that might be a factor for maneuverability at altitude.

I sure hope that is not what they teach in ATC school. The A340 is NOT underpowered, every takeoff meets regulated performance, it is the exact opposite, it is overpowered, almost every takeoff is performed with less than full thrust. We normally do not use all the thrust available to save on longer term maintenance costs.

Yes an A340 does need more runway than a 737, it is also going a lot further. Even at max weight, I almost never need to use full thrust when departing from a sea level runway at max weight, when I do it is normally due to reported windshear.

A340s do not take the "full" runway, no aircraft does with all engines operating, and the climb rates and initial altitude are often better than a 744 when both are operated at MTOW. This sounds more like a fanboy, rather than someone in industry.

Everyone knows that long haul wide bodies use more runway, and do not have the rate of climb as a short haul twin, it is not rocket science. Most airports in the US however do not get to see regular departures at MTOW, most are short to medium haul flights.

What does effect our performance is that in some countries they do not let us accelerate above our minimum clean speed, the have speed restrictions of 250 kts below 10,000 ft. Heavyweight aircraft need to climb out closer to 300 kts to get their best climb performance.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineSemaex From Germany, joined Nov 2009, 823 posts, RR: 2
Reply 15, posted (2 years 1 month 1 week 1 day 14 hours ago) and read 12797 times:

Quoting 135mech (Reply 12):
The couldn't climb out of cities fast or high enough, so that might be a factor for maneuverability at altitude.

Not exactly sure what the one has to do with the other.

Yes the A340 uses a lot of runway, because if it was going for a larger flap setting for takeoff, then the climb performance would be even worse than it is, hence lower flaps for the TOR.
That said, I'm sure an A340 would never take off on a field where it would be performance limited, so it really doesn't matter whether it takes all the runway or just half of it, as long as it is able to take off. Even for an ATC it's not such a big difference whether a 777 or an A340 is departing. Wake turbulence category is the same, and even if an aircraft is holding short wanting to cross an active runway, it doesn't matter whether the a/c taking off has a TODR of 2000 or 4000 meters.

Quoting seabosdca (Reply 11):
There is a balance between redundancy and increasing probability of failure as you increase redundancy.

That's basically what I was trying to say with my previous comment.

Quoting tjcab (Reply 10):
Why the need for ETOPS then? If cost was not a factor, I would imagine most would prefer more engines.

If cost was not a factor, I'm sure ETOPS whould be the smallest of changes we'd see in the airline industry  



// You know you're an aviation enthusiast when you look at your neighbour's cars and think about fleet commonality.
User currently offline135mech From United States of America, joined Oct 2006, 412 posts, RR: 4
Reply 16, posted (2 years 1 month 1 week 1 day 14 hours ago) and read 12230 times:
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Quoting zeke (Reply 14):
The A340 is NOT underpowered, every takeoff meets regulated performance, it is the exact opposite, it is overpowered, almost every takeoff is performed with less than full thrust.



I was specifically talking about the A342 and A343 (as i previously mentioned) NOT the A345/A346; I did NOT say the A340. The earlier ones were/are underpowered and there are plenty of pics on this site of them taking off at the END of the runways. [Along with several IL-96's] The A345/346 got the much needed engine upgrade to the frames and are much better capable acft. So, there's no need to be condescending (again) towards others that might know different things.

This quote from the pilots was what led me to this..."(... that´s better to be flying on an A330, due it´s superior performance than the A-340)."

Regards,
135Mech

[Edited 2012-08-22 14:15:52]

[Edited 2012-08-22 14:37:25]

User currently offlinefrancoflier From France, joined Oct 2001, 3775 posts, RR: 11
Reply 17, posted (2 years 1 month 1 week 1 day 13 hours ago) and read 11858 times:

If I may digress from the monthly 4 vs. 2 engines debate, I'd like to offer that when you're about to enter a stormy area over the ocean in subtropical regions, you could well have 43 engines, it won't make a hint of a difference to your chances.

Let's not take everything that comes out of pilots' mouths for unchallengeable aviation facts... It's just cockpit talk.



Looks like I picked the wrong week to quit posting...
User currently offline135mech From United States of America, joined Oct 2006, 412 posts, RR: 4
Reply 18, posted (2 years 1 month 1 week 1 day 13 hours ago) and read 11757 times:
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Quoting Semaex (Reply 15):
Quoting 135mech (Reply 12):
The couldn't climb out of cities fast or high enough, so that might be a factor for maneuverability at altitude.

Not exactly sure what the one has to do with the other.



Well, the phrase/sentence was...
"The couldn't climb out of cities fast or high enough, so that might be a factor for maneuverability at altitude."

The second part of that was where the sentence was hinged on. At altitude, you may need your engines to "help" you get out of situations from weather, etc... if your engines are smaller and slower responding, you may not get out of that situation as easily or maybe not at all.

"(... that´s better to be flying on an A330, due it´s superior performance than the A-340)."

That was what that sentence (along with the entire post) was going towards.

Not trying to get under your feathers, just putting my two cents in and using my experiences to back them up.

[Edited for spelling]

Regards,
135Mech

[Edited 2012-08-22 14:14:12]

[Edited 2012-08-22 14:17:05]

User currently offline135mech From United States of America, joined Oct 2006, 412 posts, RR: 4
Reply 19, posted (2 years 1 month 1 week 1 day 13 hours ago) and read 11568 times:
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Quoting francoflier (Reply 17):
If I may digress from the monthly 4 vs. 2 engines debate, I'd like to offer that when you're about to enter a stormy area over the ocean in subtropical regions, you could well have 43 engines, it won't make a hint of a difference to your chances.

Let's not take everything that comes out of pilots' mouths for unchallengeable aviation facts... It's just cockpit talk.



What stinks is the sad reality is we lost these lives, it's a very unfortunate thing!

[Edited 2012-08-22 14:27:35]

User currently offlineRoseflyer From United States of America, joined Feb 2004, 9661 posts, RR: 52
Reply 20, posted (2 years 1 month 1 week 1 day 13 hours ago) and read 11489 times:

Quoting zeke (Reply 14):
When the A330 and A340 are operated over the same route, with the same payload, the climb altitude would be the same, same wing. At MTOW the A340 is less than an A330 at MTOW, because it is 40+ tonnes heavier, nothing to do with the engine, it is still higher than a 777 at MTOW.

Correct me if I am wrong, but I thought climb rate depended more on thrust and efficient cruise altitude depended more on lift/wing. The A332 has a lower weight, but same life and wing as well as more thrust, so it will climb higher and faster.

Quoting zeke (Reply 14):

I sure hope that is not what they teach in ATC school. The A340 is NOT underpowered, every takeoff meets regulated performance, it is the exact opposite, it is overpowered, almost every takeoff is performed with less than full thrust. We normally do not use all the thrust available to save on longer term maintenance costs.

I couldn't agree more that it is not under powered. That's a perception issue. However the A340 certainly has a lower climb rate than the 777 (which is common between twins and quads). If you look at JFK-JNB on the A346 and JFK-HKG on the 77W, the CX 77W averages 21 minutes to cruise whereas the A346 averages 33 minutes to cruise altitude. Both typically are filed at 31,000, so the slower climb rate of the A340 gives the impression of it being underpowered.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineFabo From Slovakia, joined Aug 2005, 1219 posts, RR: 1
Reply 21, posted (2 years 1 month 1 week 1 day 11 hours ago) and read 10993 times:

Quoting zeke (Reply 14):
The A340 is NOT underpowered, every takeoff meets regulated performance, it is the exact opposite, it is overpowered, almost every takeoff is performed with less than full thrust. We normally do not use all the thrust available to save on longer term maintenance costs.

It IS underpowered - when compared to normal ops on A330 (or 777). That does not mean it has not enough thrust that it needs.

Quoting zeke (Reply 14):
Yes an A340 does need more runway than a 737, it is also going a lot further.

It might also need more runway compared to a 777 that goes just as far, but that is irrelevant, as long as it goes off.

Quoting zeke (Reply 14):
This sounds more like a fanboy, rather than someone in industry.

I guess I could tell that about you. Nothing wrong about liking and defending your plane, but you can be realistic and accept other planes are better in some ways.

Quoting Semaex (Reply 15):
Not exactly sure what the one has to do with the other.

Think vertical manuevering. The reason you are climbing is excess thrust. A twin has more excess thrust than a quad.

Quoting Semaex (Reply 15):
That said, I'm sure an A340 would never take off on a field where it would be performance limited, so it really doesn't matter whether it takes all the runway or just half of it, as long as it is able to take off.

This does not, but this is tower controller.

Quoting Semaex (Reply 15):
Even for an ATC it's not such a big difference whether a 777 or an A340 is departing.

It can be for an approach or center controller. Lets say you route your arrivals under departure track 10 miles off the airport. Assuming normal departure, 777 will be quite a bit higher than the 340.
Similarly if you need an airplane cross perpendicular airway over such and such altitude for traffic separation, 777 will use less time and track to get up there than 340 (and subsequently you might need to keep the 340 under the airway, or vector for avoidance, or similar)



The light at the end of tunnel turn out to be a lighted sing saying NO EXIT
User currently offlinebuyantukhaa From Mongolia, joined May 2004, 2899 posts, RR: 3
Reply 22, posted (2 years 1 month 1 week 1 day 10 hours ago) and read 10980 times:

Quoting Roseflyer (Reply 9):
That translates into much better climb performance.
Quoting MAUZAO (Thread starter):
And I feel much more confortable, even safer, flying over the stormy South Atlantic,

Unfortunately in this case, AF447 did still have excess thrust and could climb into a high-speed stall. Ironically, with a worse engine performance at altitude, the outcome might have been better.

While in this case the number of engines was irrelevant, the excess power worked against them here (albeit very very indirectly of course, ultimately the plane merely did what the pilots told it to do).



I scratch my head, therefore I am.
User currently offlinejollo From Italy, joined Aug 2011, 226 posts, RR: 0
Reply 23, posted (2 years 1 month 1 week 1 day 8 hours ago) and read 10934 times:

Quoting zeke (Reply 5):
a A340-600 will climb about 4000 ft higher than a 777-300ER at max weight

IIRC the 346 has a service ceiling of about 41000 ft whether the 773ER has a MOA of 43100 ft. If you try climbing to 47000+ ft with your 346, wouldn't you be violating an Airplane Flight Manual operating limitation?

Quoting zeke (Reply 14):
When the A330 and A340 are operated over the same route, with the same payload, the climb altitude would be the same, same wing

? 340-500 and -600 have almost 80 square meters more wing area than any 330.

Quoting zeke (Reply 14):
The A340 is NOT underpowered

I never claimed that.

Quoting zeke (Reply 14):
every takeoff meets regulated performance, it is the exact opposite, it is overpowered, almost every takeoff is performed with less than full thrust.

I'm relieved to hear this! Certification authorities must know what they are doing in handing out type certificates, after all... However, I was talking about climb performance at altitude, not at takoff.

Quoting zeke (Reply 14):
That is not how I was reading the OP, getting to altitude to get over weather.

There you have a point: I was talking about rate of climb, whereas the OP was probably thinking about maximum altitude. My bad.


User currently offlineLH707330 From United States of America, joined Jun 2012, 788 posts, RR: 0
Reply 24, posted (2 years 1 month 1 week 1 day 8 hours ago) and read 10928 times:

Quoting MAUZAO (Thread starter):
On a recent review on AF447 loss published on the brazilian site jetsite.com.br, first official and co-pilot on the AF plane mentioned while entering the stormy area: "... é melhor estarem voando em um A330, pois este tem performance superior ao A340" (... that´s better to be flying on an A330, due it´s superior performance than the A-340).

It's very simple. The A343 and the A332 have the same wing, but the 332 has less structural weight, payload, and fuel, and is therefore lighter. Thus you get more low end margin on your coffin corner in the 332, which was already impacted on the warm night they had. Their computer calculated limit was FL375 IIRC, and it would have been lower in a heavier (for the same mission) 343.


User currently offlinercair1 From United States of America, joined Oct 2009, 1323 posts, RR: 52
Reply 25, posted (2 years 1 month 1 week 1 day 7 hours ago) and read 11221 times:
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Quoting thenoflyzone (Reply 7):
Twice the number of engines means twice as many things could go wrong with those engines

And you can loose twice as many. It all balances out.



rcair1
User currently offlinesharles From Latvia, joined Aug 2012, 2 posts, RR: 0
Reply 26, posted (2 years 1 month 1 week 1 day 5 hours ago) and read 11216 times:

Quoting rcair1 (Reply 25):
It all balances out.

Except if one takes out the other. Having 4 engines also increases the probability of damage to other aircraft systems (as it increases the probability of catastrophic engine failure).


User currently offlinezeke From Hong Kong, joined Dec 2006, 9111 posts, RR: 75
Reply 27, posted (2 years 1 month 1 week 1 day 2 hours ago) and read 11463 times:

Quoting 135mech (Reply 16):
The earlier ones were/are underpowered and there are plenty of pics on this site of them taking off at the END of the runways.

It should be easy for you to show me one then, unless the end you mean the end they commence the takeoff roll from !!!

Quoting 135mech (Reply 16):
This quote from the pilots was what led me to this..."(... that´s better to be flying on an A330, due it´s superior performance than the A-340)."

I fly both, and I do not find them that different to operate when the are operated to their same relative capacity. That being said, I do more short haul work on A330s, and they are going out at time 50t below MTOW, they do perform differently to a A340 on a long haul that would be 90t heavier.

Quoting Roseflyer (Reply 20):
Correct me if I am wrong, but I thought climb rate depended more on thrust and efficient cruise altitude depended more on lift/wing.

True, however the difference on thrust between our A330-300s (RR) and A340s (CFM56) at sea level is only 6,000 lb, at altitude the difference is much smaller as less thrust is being produced by the fan.

Quoting Roseflyer (Reply 20):
The A332 has a lower weight, but same life and wing as well as more thrust, so it will climb higher and faster.

The QRH performance charts for all engines operating for the A330-300 and A340-300 show almost identical cruise altitudes at the same weight.

Quoting Roseflyer (Reply 20):
Both typically are filed at 31,000, so the slower climb rate of the A340 gives the impression of it being underpowered.

The 77W is typically goes to FL290, I used to go to FL330 directly at max weight in the 346.

Quoting Fabo (Reply 21):
It IS underpowered - when compared to normal ops on A330 (or 777). That does not mean it has not enough thrust that it needs.

Underpowered means the thrust is not adequate to meet performance requirements, or payload need to offloaded. The A340 even at MTOW normally takes off with less than full thrust as it is overpowered. You must to too young to remember earlier 4 holers how they used to climb, older aircraft used to have all sorts of tricks to improve performance like water injection.

Quoting Fabo (Reply 21):

It might also need more runway compared to a 777 that goes just as far, but that is irrelevant, as long as it goes off.

The 777 typically will need more runway than an A340 when calculating the takeoff performance.

Quoting jollo (Reply 23):
IIRC the 346 has a service ceiling of about 41000 ft whether the 773ER has a MOA of 43100 ft. If you try climbing to 47000+ ft with your 346, wouldn't you be violating an Airplane Flight Manual operating limitation?

Nothing about service ceiling, it is what the aircraft can achieve at max or normal operating weights. You do not get long haul aircraft operating at max altitudes unless they are very empty. At max weight on the A340 I would typically get to FL330 on a hot day, same conditions on a 77W you would be going to FL290.

Quoting jollo (Reply 23):
340-500 and -600 have almost 80 square meters more wing area than any 330.

I was comparing the A340-300 to the A330-300, essentially the same fuselage and wing, just different engine configurations.

Quoting jollo (Reply 23):
However, I was talking about climb performance at altitude, not at takoff.

And as I said before, the A340 will achieve a high initial cruise altitude than a 777 can at max weights, i.e. A340-300 better then the 777-200ER, and the A340-600 is better than the 777-300ER.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17053 posts, RR: 67
Reply 28, posted (2 years 1 month 1 week 1 day ago) and read 11335 times:

Quoting MAUZAO (Thread starter):
always imagined that the A-340, for being bigger and having 4 engines, had a much better performance than an A-330

A common misconception.

Quoting dennys (Reply 6):
Excuse me , but if i had the choice i would prefer crossing any oceans on a 4 jets aircraft !

Sure, but there's no statistical or technical basis for your preference.

Quoting 135mech (Reply 12):

My buddy started going to ATC school. One of the things they were instructed upon was that the A342/343 needed extra "time" to get off of the ground due to being underpowered on normal take off with the small CFM's. They were notorious for taking the "full" runway and their climb rates were sluggish at best. The couldn't climb out of cities fast or high enough, so that might be a factor for maneuverability at altitude.

Sure they do. But he should ask his instructors about a fully loaded 744. I dare say it will be no more sporty.

Quoting Aquila3 (Reply 13):
So, in absence of straight theories I stay with my common sense. Better four than two, God forbids one.

"Common sense" does not drive engineering. Results drive engineering. Name one incident on jets where two engines failed due to separate causes.

Quoting francoflier (Reply 17):

If I may digress from the monthly 4 vs. 2 engines debate, I'd like to offer that when you're about to enter a stormy area over the ocean in subtropical regions, you could well have 43 engines, it won't make a hint of a difference to your chances.

Let's not take everything that comes out of pilots' mouths for unchallengeable aviation facts... It's just cockpit talk.

Word. Those pilots would have crashed any airliner.

Quoting Fabo (Reply 21):
It IS underpowered - when compared to normal ops on A330 (or 777). That does not mean it has not enough thrust that it needs.

Tsk. I take "underpowered" to mean "does not mean requirements". The FAA, the JAA and the rest all agree that the 340 has enough power to meet certification requirements.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineViscount724 From Switzerland, joined Oct 2006, 25440 posts, RR: 22
Reply 29, posted (2 years 1 month 6 days 22 hours ago) and read 11014 times:

Quoting tjcab (Reply 10):
Why the need for ETOPS then? If cost was not a factor, I would imagine most would prefer more engines.

Since 2007, modified ETOPS rules have also applied to 3- and 4-engine aircraft. At least for the U.S. FAA, ETOPS now stands for "Extended Operations". The T no longer stands for "Twin".


User currently onlinericknroll From Afghanistan, joined Jan 2012, 841 posts, RR: 0
Reply 30, posted (2 years 1 month 4 days 4 hours ago) and read 10494 times:

Quoting thenoflyzone (Reply 7):
Sure, but it doesn't necessarily mean you're any safer than on a twin !

Twice the number of engines means twice as many things could go wrong with those engines.

There has been more than one quad that went on to it's destination even though they had an engine out, a twin can't do that, (depending on where it was when the engine failed).


User currently offlineB777LRF From Luxembourg, joined Nov 2008, 1367 posts, RR: 3
Reply 31, posted (2 years 1 month 3 days 21 hours ago) and read 10366 times:

It's all really very simple: Engines very rarely go wrong, whether operated under ETOPS standards or not. Thus the chances of actually loosing one are pretty low indeed. But, even so, if you loose 1 engine on a 4-holer you have an abnormal situation. If you loose 1 engine on a twin, you have an emergency.

I know which one I prefer.



From receips and radials over straight pipes to big fans - been there, done that, got the hearing defects to prove
User currently offlinethegeek From Australia, joined Nov 2007, 2638 posts, RR: 0
Reply 32, posted (2 years 1 month 3 days 4 hours ago) and read 10109 times:

Quoting zeke (Reply 14):
The A340 is NOT underpowered, every takeoff meets regulated performance, it is the exact opposite, it is overpowered, almost every takeoff is performed with less than full thrust.

By that definition, isn't every aircraft overpowered? Would it be true to say that it is less overpowered than other aircraft?


User currently offlineStarlionblue From Greenland, joined Feb 2004, 17053 posts, RR: 67
Reply 33, posted (2 years 1 month 3 days 1 hour ago) and read 10060 times:

Quoting thegeek (Reply 32):
Quoting zeke (Reply 14):
The A340 is NOT underpowered, every takeoff meets regulated performance, it is the exact opposite, it is overpowered, almost every takeoff is performed with less than full thrust.

By that definition, isn't every aircraft overpowered? Would it be true to say that it is less overpowered than other aircraft?

:D

Getting into semantics I guess. But surely modern aircraft all have more power than necessary to do the job. In part this may be because derating saves engine life, so it might be better to have more power available and not use it than to firewall the engines on every take-off.

Operators only care about excess power (defined as "beyond regulatory minimum requirements") to the extent that it supports the mission. So sure, they'll want more power, but only if it is needed to, say, fly further or heavier.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinejollo From Italy, joined Aug 2011, 226 posts, RR: 0
Reply 34, posted (2 years 1 month 2 days 22 hours ago) and read 9975 times:

Quoting zeke (Reply 27):
And as I said before, the A340 will achieve a high initial cruise altitude than a 777 can at max weights, i.e. A340-300 better then the 777-200ER, and the A340-600 is better than the 777-300ER.

Looks like I'm unable to make myself clear, let me try again with a theoretical situation without any A vs. B strain: A330-300 vs. A340-300 (same wing, different engine configurations, say 2xTrent 700 vs. 4xCFM-56), in level formation flight at FL310, same speed (say M0.78), *same gross weight* at a given instant (and never mind how they got there). At that instant they start together a max rate climb to FL350: which one will get there first (least time)?

IIRC, that boils down to asking which a/c has the highest excess power (not thrust) given the initial conditions.

I don't have a point to prove, I'm genuinely curious. Thanks.

[Edited 2012-08-28 05:41:42]

User currently offlineStarlionblue From Greenland, joined Feb 2004, 17053 posts, RR: 67
Reply 35, posted (2 years 1 month 2 days 19 hours ago) and read 9931 times:

Quoting jollo (Reply 34):
Looks like I'm unable to make myself clear, let me try again with a theoretical situation without any A vs. B strain: A330-300 vs. A340-300 (same wing, different engine configurations, say 2xTrent 700 vs. 4xCFM-56), in level formation flight at FL310, same speed (say M0.78), *same gross weight* at a given instant (and never mind how they got there). At that instant they start together a max rate climb to FL350: which one will get there first (least time)?

IIRC, that boils down to asking which a/c has the highest excess power (not thrust) given the initial conditions.

All other things being equal, the 330 would have more power, so would reach FL350 first. This is the nature of engine-out regs.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineferpe From France, joined Nov 2010, 2804 posts, RR: 59
Reply 36, posted (2 years 1 month 2 days 16 hours ago) and read 9865 times:

There is a lot of flak spread over the A340 and especially over the A340-300. If I understand it right this is however one of the more economical on fuel in the 340 family.

This is of course the case for trip vs. the -600 but on a typical 10 hour flight it seems the 340-300, -600 and the 330-200 are pretty close on fuel consumed per pax. The 330-300 would be some 10% better per pax over the 332, 343 and 346. Given that the 340-300 is lower on fuel burn per trip then the -600 is should be more flexible in use if your load-factors vary over the year or week.

I therefore don't understand all the bad words about the 340-300 vs the 340-600, if I don't have routes that can motivate 350 pax frames the -300 should be the better asset then the -600, the trip fuel diff seems to be in the 20% range.

Of course a 333 is the best asset if you only have to go 10 hour legs or less, but if you have the occasional 13-14 hours legs the choice between the 332 and 343 is then really how many pax do you need to haul, 250-ish or more like 300.

Of course engine overhaul cost will hit the 343 and skew the balance more towards the 330 range, now how long-lived are those maxed CFMs on a 340 wing compared to the 330 engines?



Non French in France
User currently offlinethegeek From Australia, joined Nov 2007, 2638 posts, RR: 0
Reply 37, posted (2 years 1 month 2 days 12 hours ago) and read 9778 times:

Quoting Starlionblue (Reply 35):
All other things being equal, the 330 would have more power, so would reach FL350 first. This is the nature of engine-out regs.

Perhaps so, but the A340 wouldn't be too far behind it if they both started at the same weight. The A340 uses its one engine out advantage to haul more weight normally, but if the starting weight is the same, there isn't much difference.


User currently offlinejollo From Italy, joined Aug 2011, 226 posts, RR: 0
Reply 38, posted (2 years 1 month 2 days 2 hours ago) and read 9649 times:

Quoting Starlionblue (Reply 35):
All other things being equal, the 330 would have more power, so would reach FL350 first. This is the nature of engine-out regs.

I think you're correct, but I don't know by how much: one would need the actual speed polars of both ac to quantify the difference. I'd also like to hear the voice of direct experience from zeke.

That said, I'm a fan of the A340 as a passenger: arguably one of the best-looking airliners flying, great comfort for ULR, great reliability, and obviously "right-powered" (or it wouldn't fly daily the longest legs worldwide). I would love a fresh production run with new engines and all the tweaks developed in the meantime for the 330. Alas, it's not gonna happen.


User currently offlineStarlionblue From Greenland, joined Feb 2004, 17053 posts, RR: 67
Reply 39, posted (2 years 1 month 2 days 2 hours ago) and read 9645 times:

Quoting jollo (Reply 38):
Quoting Starlionblue (Reply 35):
All other things being equal, the 330 would have more power, so would reach FL350 first. This is the nature of engine-out regs.

I think you're correct, but I don't know by how much: one would need the actual speed polars of both ac to quantify the difference. I'd also like to hear the voice of direct experience from zeke.

I said "all other things being equal", meaning only engine power is different. Same MTOW in other words. With the same MTOW, the same wing and much more power on the 330 it stands to reason it can climb faster. Probably much faster since climb performance is directly correlated to excess thrust.

Definitely a theoretical exercise with little validity in the real world. Big grin

[Edited 2012-08-29 01:45:08]


"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinetom355uk From United Kingdom, joined Nov 2007, 336 posts, RR: 3
Reply 40, posted (2 years 1 month 1 day 20 hours ago) and read 9594 times:

Quoting Starlionblue (Reply 39):
much more power on the 330

That's not exactly true is it?? 

The 4 x CFM56-5C's on most A340's have 34k each, whereas 2 x Trent 772's on an A330 have about 71k each, and that is at Sea Level, Standard Day.

At FL350, where the fan makes much less difference to the thrust produced I would guess it is much, much closer than people would think.

I remember reading somewhere about the correlation between static SL thrust and aloft, 0.2-0.25 seems to stick in my mind but I can't be 100% on that.



on Twitter @tombeckett2285
User currently offlineymincrement From Turkey, joined Jul 2012, 26 posts, RR: 0
Reply 41, posted (2 years 1 month 1 day 16 hours ago) and read 9490 times:

I would prefeer being in the middle of 4 engine when crossing the ocean but it may be my psychological needabout safety..  



but what you prefer when you have to overtake on the left ? 4 cylinder classical VW or V8 bmw or a benz?  

thanks
Onur


User currently offlineStarlionblue From Greenland, joined Feb 2004, 17053 posts, RR: 67
Reply 42, posted (2 years 1 month 1 day 11 hours ago) and read 9375 times:

Quoting tom355uk (Reply 40):
Quoting Starlionblue (Reply 39):
much more power on the 330

That's not exactly true is it?? 

The 4 x CFM56-5C's on most A340's have 34k each, whereas 2 x Trent 772's on an A330 have about 71k each, and that is at Sea Level, Standard Day.

Oops. I guess I walked into that one. "All other things being equal"!!! 
Quoting ymincrement (Reply 41):
I would prefeer being in the middle of 4 engine when crossing the ocean but it may be my psychological needabout safety..

Exactly. Yes, two engines can fail for unrelated reasons but it is so unlikely that the risk is completely acceptable.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinethegeek From Australia, joined Nov 2007, 2638 posts, RR: 0
Reply 43, posted (2 years 1 month 1 day 8 hours ago) and read 9340 times:

Quoting tom355uk (Reply 40):
That's not exactly true is it??

The only part untrue is the exaggeration "much".


User currently offlineatct From United States of America, joined Mar 2001, 2298 posts, RR: 38
Reply 44, posted (2 years 1 month 4 hours ago) and read 9102 times:

Quoting zeke (Reply 14):
A340s do not take the "full" runway, no aircraft does with all engines operating, and the climb rates and initial altitude are often better than a 744 when both are operated at MTOW. This sounds more like a fanboy, rather than someone in industry.

Im currently a radar controller and in my experience A340's are pigs. They dont speed up fast or climb fast. I liken them to the classic 747's (-100/200/300) when im working them. When I worked a tower we had Lufthansa and China Airlines A340's and again, both were pigs. They ate up alot of runway (11,000ft +/-) and climbed like dogs. The triple sevens (British Airways, Continental, Air France) didnt eat up as much and climbed better. The Classic 747's were pigs but the newer ones, once up to speed, climb awesome. I dont work many A330's (used to work Air France A332's, now occaisonally Korean Air A330's) but from what ive seen I liken them to 763's or Md11's. Not awesome but not bad for a heavy. When it comes to performance, give me a 77L going 5000nm anyday. Emirate's 77's going IAH-DXB were a little doggy, but still not in the league of A343's or 742's.

So yes, I teach my trainees never to count on an A340 "topping" someone. The 77L, anyday of the week. The A343 (or B742), never. I know its all about weight, but overall in my experience, A343's are pigs.

atct



"The way to get started is to quit talking and begin doing." - Walt Disney
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17053 posts, RR: 67
Reply 45, posted (2 years 1 month 3 hours ago) and read 9060 times:

Quoting atct (Reply 44):
I know its all about weight, but overall in my experience, A343's are pigs.

Yes, they climb slower. But airlines care about economics, not sportscar performance.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinezeke From Hong Kong, joined Dec 2006, 9111 posts, RR: 75
Reply 46, posted (2 years 1 month ago) and read 9063 times:

Quoting jollo (Reply 34):
A330-300 vs. A340-300 (same wing, different engine configurations, say 2xTrent 700 vs. 4xCFM-56), in level formation flight at FL310, same speed (say M0.78), *same gross weight* at a given instant (and never mind how they got there). At that instant they start together a max rate climb to FL350: which one will get there first (least time)?

They would almost be identical. If anything the A340 might be a little better, the CFMs are a little more responsive for thrust changes, they would spool up faster at that level. Flying at 0.78 would have both aircraft engines operating below normal cruise thrust levels.

Quoting jollo (Reply 34):

IIRC, that boils down to asking which a/c has the highest excess power (not thrust) given the initial conditions.

True, and give the same mach and level, TAS is the same, so it is a matter of excess thrust. The speeds for best rate are slight different between the two.

Quoting tom355uk (Reply 40):

At FL350, where the fan makes much less difference to the thrust produced I would guess it is much, much closer than people would think.

Agreed, looking at takeoff performance, the A330 drops off quicker as density height increases.

Quoting atct (Reply 44):

Im currently a radar controller and in my experience A340's are pigs. They dont speed up fast or climb fast. I liken them to the classic 747's (-100/200/300) when im working them.

I do not care what ATC thinks when I am flying, we look after our aircraft. ATC is there to facilitate the traffic, the traffic is not there to facilitate ATC. I normally never do toga takeoffs, and full thrust climbs, that reduces longer term maintenance costs.

Quoting atct (Reply 44):
When I worked a tower we had Lufthansa and China Airlines A340's and again, both were pigs.

Compared to what types doing what sectors ? with what loads ? what engines ? what speeds ? Without any of the additional information, your comments are idle observations.

Quoting atct (Reply 44):
They ate up alot of runway (11,000ft +/-) and climbed like dogs. The triple sevens (British Airways, Continental, Air France) didnt eat up as much and climbed better.

A340s use less runway than 777s.

Quoting atct (Reply 44):
Emirate's 77's going IAH-DXB were a little doggy, but still not in the league of A343's or 742's.

Our 77W cannot climb as high as an A340 at max weight. The A340-300 will also out climb a 744.

Please review my reply 35 in A340 Lack Of Power - Is It True? (by NEMA Oct 10 2008 in Tech Ops) for some factual comparisons.

Quoting Starlionblue (Reply 45):
Yes, they climb slower. But airlines care about economics, not sportscar performance.

Exactly, the A340 is a gentleman's aircraft, nothing happens fast, and nothing bites. Engine failure after takeoff is hardly noticeable, you know you have heaps of thrust, you know you will clear terrain, and you know you do not have an emergency. Flying a quad in turbulence like a typhoon is much easier than a twin, the thrust couple is not as great, and you only need 4 smaller thrust movements compared to two larger thrust movements on a twin.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineB777LRF From Luxembourg, joined Nov 2008, 1367 posts, RR: 3
Reply 47, posted (2 years 4 weeks 1 day 2 hours ago) and read 8857 times:

Listen, we all know a 340 Classic doesn't leap very sprightly off the ground. Neither does a heavy 747 for that matter. But they are not under-powered, they are just not over-powered the way twins have to be.

I've stood watching a GF A340 trying to defy gravity and attempt to reach BKK or MNL direct from BAH. At 2 in the afternoon, in the July heat. No mean thing for anybody, and that thing just hung there until it vanished in the haze, doing it's best, but generally failing, to overcome gravitational pull and gain altitude. Now the reason I was standing there was because of the first 3S 777F departure to HKG, I think it was. Less than 20 tons of payload onboard, less than half a tank of fuel, and because the aircraft was new they were not yet allowed to do de-rated take-offs. That think came off the ground half way down the runway and shot up like a rocket. And it kept going until it reached F410, whereas I'd hazard a guess the poor A340 would have struggled to reach 10.000 ft before entering Indian airspace. Well, perhaps a bit earlier then  

But is that a fair comparison between the two? Eh, hardly. I know which one is more fun to take-off in, I used to fly the 757, but I'm also of the kind who likes to be surrounded by as many engines as possible when crossing large pieces of nothingness. And for that reason I'll hang in there, willing the poor thing to go up where the air is thin, cause I'd rather have 4 hair-dryers hanging off the wing of a 340 Classique than two industrial grade turbines under a 330, 767, 777 etc. And if it wasn't for the noisy, I'd be even happier to sit in a 747 even if she's hardly an early day altitude master either on a heavy day.

Note that I left the A380 out. That thing needs neither more power or wing. Jeebus, she climbs!



From receips and radials over straight pipes to big fans - been there, done that, got the hearing defects to prove
User currently offlineAirlineCritic From Finland, joined Mar 2009, 718 posts, RR: 1
Reply 48, posted (2 years 4 weeks 1 day 1 hour ago) and read 8819 times:

Obviously, people will want a powerful aircraft.

How would we otherwise leave other aircraft standing still, when the light changes to green in an intersection? And isn't power also needed if you need to impress the stewardesses with a quick donut on the runway?


User currently offlineFabo From Slovakia, joined Aug 2005, 1219 posts, RR: 1
Reply 49, posted (2 years 3 weeks 6 days 18 hours ago) and read 8558 times:

Quoting zeke (Reply 46):
A340s use less runway than 777s.

I believe you that is the truth when using TOGA.

Now, a little mental excercise for FLEX takeoffs. Lets suppose the aircraft is go-limited (because brakes count into stop-limited, and we are not talking brakes).

So, suppose there is a 777 which would normally need 9000ft on a 12000ft runway, AST take-off (same thing as FLEX).
My line of thinking is, 777 uses 200% of single engine AST thrust to accelerate 0-V1 and 100% of thrust to accelerate V1-Vlof. (in V1 cut - limiting situation)

A340 is next in line, and would normally need 7500ft. Uses FLEX.
This A340 uses 133% of OEI thrust to accelerate 0-V1 and 100% V1-Vlof.

As I look at it, A340 will need bigger portion of the runway to get to V1, and then almost the same distance to Vlof on all engines as it would in V1 cut situation.
777 will use smaller part of the runway to get to V1, so it can use big chunk of left runway to accelerate to Vlof if one engine quits.

However, if neither engine quits, it will get to Vlof quickly, and will lift off sooner than A340.


I tried to put my thought into image. Red line is trajectory of either aircraft in case of V1 cut. Blue is normal 777 trajectory and green is normal A340 trajectory.



The light at the end of tunnel turn out to be a lighted sing saying NO EXIT
User currently offlinezeke From Hong Kong, joined Dec 2006, 9111 posts, RR: 75
Reply 50, posted (2 years 3 weeks 6 days 17 hours ago) and read 8549 times:

Quoting Fabo (Reply 49):

Takeoff distances are all done OEI.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineFabo From Slovakia, joined Aug 2005, 1219 posts, RR: 1
Reply 51, posted (2 years 3 weeks 5 days 21 hours ago) and read 8309 times:

Quoting zeke (Reply 50):
Takeoff distances are all done OEI.

Yes, but takeoff dont all happen that way. Therefore 777 will lift off sooner and would "use less runway" and "climb better" as apperaing to casual observer.



The light at the end of tunnel turn out to be a lighted sing saying NO EXIT
User currently offlineatct From United States of America, joined Mar 2001, 2298 posts, RR: 38
Reply 52, posted (2 years 3 weeks 5 days 14 hours ago) and read 8247 times:

I do facilitate traffic. When I see an A343 coming I can assure you that they get baby treatment. If its a choice between turning a 777 on course or an A343, the triple gets it everytime. Airplanes that perform well in my sector get turned and climbed first. I wont risk a doggy 343 driver who wants to save a few bucks by climbing slow topping my final. You can say all you want about it "being a better performer" but performance not being used is wasted. If ya'll used the performance you claim, then maybe the rest of the industry wouldnt think its a pig. At least with the C-46's I know that they are giving it all she's got. Until then, the A343 still a pig and is probably the last airplane I ever want to see entering my scope.

atct



"The way to get started is to quit talking and begin doing." - Walt Disney
User currently offlinezeke From Hong Kong, joined Dec 2006, 9111 posts, RR: 75
Reply 53, posted (2 years 3 weeks 5 days 9 hours ago) and read 8167 times:

Quoting atct (Reply 52):

That is the sort of attitude that costs the traveling public millions of dollars every year. Every airline tries to operate their aircraft with reduced or derated thrust as it saves on long term maintenance costs. The reduced maintenance costs allows the industry to pass on better value to the public, it also gives the engine less stress, and better margins, and should also reduce the probability of an engine failure.

I will bring this up with out OPS people at the sort of inefficiencies ATC give us, we will use it as ammo to reduce fees, and the ATC providers will use is as ammo to reduce their inefficient staff costs.

ATC is there to facilitate ALL traffic efficiently, you are not paid to operate aircraft, or to make operational decisions, it takes a different skill set. We have different priorities, ATC is one of the lower priorities, the classic order is aviate, navigate, communicate.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently onlinePihero From France, joined Jan 2005, 4506 posts, RR: 76
Reply 54, posted (2 years 3 weeks 5 days 1 hour ago) and read 8084 times:
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Quoting zeke (Reply 53):

ATC is there to facilitate ALL traffic efficiently, you are not paid to operate aircraft, or to make operational decisions, it takes a different skill set.

     

Super post and I can't agree more; The question is also : " How do you treat a loaded 747 ? "... The answer could be interesting.



Contrail designer
User currently offlineatct From United States of America, joined Mar 2001, 2298 posts, RR: 38
Reply 55, posted (2 years 3 weeks 4 days 11 hours ago) and read 7902 times:

Quoting zeke (Reply 53):
ATC is there to facilitate ALL traffic efficiently

Efficiently is the word. I dont go out of my way to help out a slow climber, whether A343 or heavy 742, because that delays everyone else. Everything I do is about system, not individual, efficiency.

atct



"The way to get started is to quit talking and begin doing." - Walt Disney
User currently offlineecbomberman From Hong Kong, joined Mar 2011, 76 posts, RR: 0
Reply 56, posted (2 years 3 weeks 3 days 23 hours ago) and read 7783 times:

Why are there people always criticizing A343/2's performance? If they are that underpowered, they wouldn't have gained their FAA certificate. It seems that there will always be people with the 'bigger is better' or 'more power is better' attitude in this website.

If what you want is not an underpower takeoff (i.e.: pushing you back to your seats, steep take off gradient), you can always experience that in any theme park any day (or choose an airline with that flies a 2 holer). But I would hazard a guess that airlines do care about fuel consumption rather than doing TOGA takeoffs to impress the yeee-haaa passengers.

I do remember that a couple of years ago that zeke mentioned that most A343 take offs only uses the equivalent thrust of 3 engines running at full power.

I can truly dispute that the A343 is not underpowered. Back in the summer in 2001, I was on a VS flight from LHR-HKG and there was a Typhoon in the vicinity of HK. we've been doing holding for 1-2hrs before attempting to land. We had to go-round the first time round but the secound attempt was truly scary. I was sitting at the rear window side of the plane and I swear that we were feets from the ground before the pilot decide to do a G/A. Trust me, the pitch and rate of climb is not what you call underpowered. People were screaming like hell as the positive G was pushing us into the seat. Yes, granted the plane might be very light at the end of a 12hr flight, but don't underestimate the power needed to overcome windshear and severe turbulent conditions in a Typhoon situation.

In the end of the day, both Boeing and Airbus and any other aircraft manufacture WILL NOT deliberately design a plane to be underpowered and/or crash.



VS343/346/744 CX744/L1101/343 MH332/333/733 BD32x/EMB 145 AK320 SQ310/77E/773/744 UA747SP/744 BA744 BI763ER/319 QF763ER
User currently offlineecbomberman From Hong Kong, joined Mar 2011, 76 posts, RR: 0
Reply 57, posted (2 years 3 weeks 3 days 22 hours ago) and read 7763 times:

Quoting atct (Reply 55):
Quoting atct (Reply 55):
Efficiently is the word. I dont go out of my way to help out a slow climber, whether A343 or heavy 742, because that delays everyone else. Everything I do is about system, not individual, efficiency.

Does 250kts under 10k apply in your situation? Would that have an impact on the climb rate?



VS343/346/744 CX744/L1101/343 MH332/333/733 BD32x/EMB 145 AK320 SQ310/77E/773/744 UA747SP/744 BA744 BI763ER/319 QF763ER
User currently offlineFabo From Slovakia, joined Aug 2005, 1219 posts, RR: 1
Reply 58, posted (2 years 3 weeks 3 days 21 hours ago) and read 7749 times:

Quoting ecbomberman (Reply 56):
In the end of the day, both Boeing and Airbus and any other aircraft manufacture WILL NOT deliberately design a plane to be underpowered and/or crash.

Geez, will some people learn to READ? NOWHERE was it said that A340 was dangerous, or underpowered IN REGARD TO REGULATIONS!
Simply that it uses less thrust than a twin of comparable mass. What the hell is wrong with that?
If people were talking about a car doing 200km/h would you jump up and say that your car can break the speed limit too?

Quoting ecbomberman (Reply 57):
Does 250kts under 10k apply in your situation? Would that have an impact on the climb rate?

250kts under 10K are (almost) always void when minimum clean speed is higher. That does happen to heavy widebodies, in that case, they may climb at minimum clean speed. In such a case, climb speed will be better compared to keeping flaps and under 250.



The light at the end of tunnel turn out to be a lighted sing saying NO EXIT
User currently offlineecbomberman From Hong Kong, joined Mar 2011, 76 posts, RR: 0
Reply 59, posted (2 years 3 weeks 3 days 21 hours ago) and read 7736 times:

Quoting Fabo (Reply 58):
Quoting Fabo (Reply 58):
Geez, will some people learn to READ? NOWHERE was it said that A340 was dangerous, or underpowered IN REGARD TO REGULATIONS!

I think you've misunderstood me there and just reading part of what I wrote. What I mean is that all aircrafts are safe and that no insane aircraft manufacture will deliberately make it UNSAFE.

I think you will understand my point of view better if you read the whole post where I did commend the performance of A343. I would appreciate if you can take your time and re-read my post  
Quoting Fabo (Reply 58):
Quoting Fabo (Reply 58):
250kts under 10K are (almost) always void when minimum clean speed is higher. That does happen to heavy widebodies, in that case, they may climb at minimum clean speed. In such a case, climb speed will be better compared to keeping flaps and under 250.

I know a clean A/C will climb better. Just want to make sure that this is the case in the US as one ATC controller did mention:

Quoting atct (Reply 52):
Quoting atct (Reply 52):
Until then, the A343 still a pig and is probably the last airplane I ever want to see entering my scope.


[Edited 2012-09-05 06:51:07]

[Edited 2012-09-05 06:52:09]

[Edited 2012-09-05 06:52:58]

[Edited 2012-09-05 06:54:00]


VS343/346/744 CX744/L1101/343 MH332/333/733 BD32x/EMB 145 AK320 SQ310/77E/773/744 UA747SP/744 BA744 BI763ER/319 QF763ER
User currently offlineFabo From Slovakia, joined Aug 2005, 1219 posts, RR: 1
Reply 60, posted (2 years 3 weeks 3 days 20 hours ago) and read 7708 times:

Quoting ecbomberman (Reply 59):
I think you've misunderstood me there and just reading part of what I wrote. What I mean is that all aircrafts are safe and that no insane aircraft manufacture will deliberately make it UNSAFE.

OF COURSE they would not. Why do people keep bringing it up then? The whole debate runs around quads being overperformed by twins in normal operation exactly because of those regulations that define safe and unsafe.

Of course in abnormal situation they perform the same, or rather, even better, but we are not talking OEI.

That is why I say that there is little point in repeating that your car, which does 150, does also break speed limit (lets say it is for some weird reason minimal speed required, not maximal allowed) when other people say that car that does 200 is faster and has more power. While your car is overpowered in regards to minimum power needed, it is underpowered compared to the other car.

Still, I am sorry if you felt I was needlessly aggressive. Just having a bad day IRL.

Quoting ecbomberman (Reply 59):
I just want to make sure that this is the case in the US as one ATC controller did mention:

Yes it is, ref. FAR Part 91 sect. 91.117 paragraph D: " If the minimum safe airspeed for any particular operation is greater than the maximum speed prescribed in this section[that is, 250 kts under 10,000ft MSL], the aircraft may be operated at that minimum speed."

However, it will still perform worse than other types, mainly twins, which have more excess thrust (assuming comparable ATOW and MTOW)



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User currently offlineecbomberman From Hong Kong, joined Mar 2011, 76 posts, RR: 0
Reply 61, posted (2 years 3 weeks 3 days 20 hours ago) and read 7708 times:

Quoting Fabo (Reply 60):

I think both you and I have a common ground in that there is no UNDERPOWERED plane. People who say that do not possess true knowledge of aviation. Yes, and I agree with you that the climb rates differ between quads and twins.

No offence taken  



VS343/346/744 CX744/L1101/343 MH332/333/733 BD32x/EMB 145 AK320 SQ310/77E/773/744 UA747SP/744 BA744 BI763ER/319 QF763ER
User currently offlinezeke From Hong Kong, joined Dec 2006, 9111 posts, RR: 75
Reply 62, posted (2 years 3 weeks 3 days 20 hours ago) and read 7743 times:

Quoting Fabo (Reply 60):

The A340-300 has a 40+ t higher MTOW than an A330-300 for much the same thrust with the same wing. An A340-300 will out climb a a 744, and the A340-600 will out climb a 77W.

What people do not see is these aircraft operating at or ner their max limits often, and try and compare short to medium haul performance to ULH. It is an invalid comparison. They do not want to mention how well these long haul aircraft perform on shorter sectors even with max passenger loads.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineecbomberman From Hong Kong, joined Mar 2011, 76 posts, RR: 0
Reply 63, posted (2 years 3 weeks 3 days 20 hours ago) and read 7716 times:

Quoting zeke (Reply 62):
Quoting zeke (Reply 62):
What people do not see is these aircraft operating at or ner their max limits often, and try and compare short to medium haul performance to ULH. It is an invalid comparison. They do not want to mention how well these long haul aircraft perform on shorter sectors even with max passenger loads.

I would be intrigued to know the performance between a A332 and A343 doing HKG-CDG. Both are long haul flights and AF does occasionally send their A332 to HKG.

http://www.airliners.net/photo/Air-F...d=dad55c41a27c1533d5007a23376fb678

What would be MTOW be for both aircraft and will the initial cruise altitude be the same? Would be A332 be restricted in any ways?



VS343/346/744 CX744/L1101/343 MH332/333/733 BD32x/EMB 145 AK320 SQ310/77E/773/744 UA747SP/744 BA744 BI763ER/319 QF763ER
User currently offlineaerotech777 From United States of America, joined Aug 2009, 68 posts, RR: 0
Reply 64, posted (2 years 2 weeks 5 days 11 hours ago) and read 7202 times:

Quoting zeke (Reply 50):
: Takeoff distances are all done OEI

I am not performance expert. But I thought that AEO (all engines operating) accelerate-stop distance is also part of
takeoff performance and it is more limiting than OEI. May be someone (performance guru or performance engineer) can
shed some light on this point.

Regards.


User currently onlinePihero From France, joined Jan 2005, 4506 posts, RR: 76
Reply 65, posted (2 years 2 weeks 5 days 10 hours ago) and read 7203 times:
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Quoting aerotech777 (Reply 64):
I thought that AEO (all engines operating) accelerate-stop distance is also part of
takeoff performance and it is more limiting than OEI.

There is no such thing as an "accelerate-stop distance with all engines operating" in our performance considerations. ( why reject a takeoff when the engines are performing correctly ?... moreover that distance will always be inferior to an ASD for loss of an engine. )
But in some cases, the take off distance and the takeoff run with all engines operating could be more limiting than with an engine frailure, simply because the criteria are more stringent ( roughly, the tested distance would bbe factored by 115% )
Btw, the definitions apply not to an engine out or one engine inoperative but performance with N (meaning "all" engines) or N-1 (meaning the los of the "most critical" engine). Therefore, we would be talking about TOD(N dry) or TOR (N-1 dry or wet).... etc...



Contrail designer
User currently offlinezeke From Hong Kong, joined Dec 2006, 9111 posts, RR: 75
Reply 66, posted (2 years 2 weeks 5 days 3 hours ago) and read 7158 times:

Quoting aerotech777 (Reply 64):
I am not performance expert. But I thought that AEO (all engines operating) accelerate-stop distance is also part of
takeoff performance and it is more limiting than OEI. May be someone (performance guru or performance engineer) can
shed some light on this point.

Yes it is, but I have never been out of an airport limited by that, only OEI. The rule says that the takeoff distance is the greater of the OEI to 35 ft, or 1.15 of the takeoff distance on all engines to 35.

(FAR 25.113

[(a) Takeoff distance on a dry runway is the greater of--
(1) The horizontal distance along the takeoff path from the start of the takeoff to the point at which the airplane is 35 feet above the takeoff surface, determined under Sec. 25.111 for a dry runway; or]
(2) 115 percent of the horizontal distance along the takeoff path, with all engines operating, from the start of the takeoff to the point at which the airplane is 35 feet above the takeoff surface, as determined by a procedure consistent with Sec. 25.111.)



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineaerotech777 From United States of America, joined Aug 2009, 68 posts, RR: 0
Reply 67, posted (2 years 2 weeks 11 hours ago) and read 6699 times:

Quoting Pihero (Reply 65):
There is no such thing as an "accelerate-stop distance with all engines operating" in our performance considerations. ( why reject a takeoff when the engines are performing correctly ?... moreover that distance will always be inferior to an ASD for loss of an engine. )

With all my respect to you, but may be you are not aware about accelerate-stop distance with all engines operating. You can reject a takeoff for a problem that is not related to engine. That's why there is accelerate-stop distance with all engines operating. I read somewhere that usually AEO accelerate-stop distance is bigger than than OEI accelerate stop distance. Here is the reason if I remember correctly: you have 2 engines operating aircraft versus one engine operating aircraft (assuming it is twin) and the thrust reversers are not taken in consideration in dry runway. So the accelerate-stop distance with AEO is bigger than the accelerate-stop distance with OEI.

Quoting zeke (Reply 66):
Yes it is, but I have never been out of an airport limited by that, only OEI. The rule says that the takeoff distance is the greater of the OEI to 35 ft, or 1.15 of the takeoff distance on all engines to 35.

This is FAR 25.113, but there is also FAR 25.109 that talks about accelerate-stop distance. If I am not mistaken the takeoff distance is the greater of the 3 distances: accelerate-go distance with AEO, accelerate-go distance with OEI, and the accelerate-stop distance (the greater of AEO and OEI).

I stand to be corrected.

Regards


User currently onlinePihero From France, joined Jan 2005, 4506 posts, RR: 76
Reply 68, posted (2 years 1 week 6 days 17 hours ago) and read 6462 times:
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Quoting aerotech777 (Reply 67):
may be you are not aware about accelerate-stop distance with all engines operating.

My bad. I was rushing to discuss your # 64 : In my experience, the ASD (N) is always less restrictive than ASD (N-1) - the all engine acceleration to V1 will make that sure.

Quoting aerotech777 (Reply 67):
If I am not mistaken the takeoff distance is the greater of the 3 distances: accelerate-go distance with AEO, accelerate-go distance with OEI, and the accelerate-stop distance (the greater of AEO and OEI).

Not quite :
One has to consider that we have to operate on one real physical runway, the length of which is used for takeoff run calculations - TORA (n) or TORA (n-1) and additions called "stopway" - used for Accelerate/stop performance : ASD (n) or ASD (n-1) - and "clearway", used for takeoff distance performance : TODA (n) or TODA (n-1). Each one of these calculations leads to a weight, the lightest being the MTOW for the day's conditions.
(There are further considerations like the chioice of a V1 inside a range, but this goes outside the scope of the discussion)



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