Moderators: richierich, ua900, PanAm_DC10, hOMSaR

 
jetblue777
Topic Author
Posts: 1204
Joined: Fri Jul 17, 2009 4:13 pm

What's The Major Benefit Of Having Four Engines?

Sat Jan 15, 2011 11:14 pm

Hey guys,

I've been wondering, what's the major benefit of having four engines than two? I mean, four engines means more engines = more money and maintenance. Say, the Airbus A340-600, it has around the same capacity as the A330-300 and the A333 is much cheaper and since it has only two engines, so less maintenance. More Engines = Faster Speed? or no?

I know the major benefit of the A345 is that it can fly ultra long haul flights (EWR-SIN-EWR) But how about the A343? A346? But the 77L can do the same thing with two engines.

And how about the MD-11 and DC-10 with three engines? What was the major benefit of the third engine?
It's a cultural thing.
 
BMI727
Posts: 11300
Joined: Mon Feb 02, 2009 9:29 pm

RE: What's The Major Benefit Of Having Four Engines?

Sat Jan 15, 2011 11:26 pm

These days, the benefits are rather reduced.

From a passenger perspective:
1. The engines are probably less powerful than an equivalent twin.
2. Two of those engines are further away from the fuselage.
So, basically, a quad may be quieter.

From an airlines perspective:
1. An engine failure means losing 1/4 of your thrust instead of 1/2, which makes hot and high destinations more practical in some cases.
2. Access to the relatively small portions of airspace still off limits to twins.

There are probably more, but I think that's the big ones.
Why do Aerospace Engineering students have to turn things in on time?
 
comorin
Posts: 3858
Joined: Sun May 29, 2005 5:52 am

RE: What's The Major Benefit Of Having Four Engines?

Sun Jan 16, 2011 12:54 am

Not to mention that should you lose 2 engines you can still fly.
 
Viscount724
Posts: 19316
Joined: Thu Oct 12, 2006 7:32 pm

RE: What's The Major Benefit Of Having Four Engines?

Sun Jan 16, 2011 1:39 am

Quoting BMI727 (Reply 1):
1. An engine failure means losing 1/4 of your thrust instead of 1/2, which makes hot and high destinations more practical in some cases.

Also means fewer restrictions if there are terrain issues near the airport in the event of an engine failure. I believe there are also some routes over high mountain ranges (e.g. the Himalayas) that 4-engine types can use that 2-engine types can't, as a 2-engine type at high weights may not be able to maintain a high enough altitude to clear 29,000 ft. mountains following an engine failure.
 
WingedMigrator
Posts: 1771
Joined: Wed Oct 26, 2005 9:45 am

RE: What's The Major Benefit Of Having Four Engines?

Sun Jan 16, 2011 5:26 am

Quoting BMI727 (Reply 1):
There are probably more, but I think that's the big ones

You forgot the biggest and most obvious benefit: you can generate more thrust using 4 engines than with 2 (of reasonable size). Very heavy airplanes need more thrust than can be provided by 2 engines. As engines have become larger, that demarcation line has moved higher, to about 350 tonnes, but it nevertheless remains.
 
User avatar
Starlionblue
Posts: 20643
Joined: Fri Feb 27, 2004 9:54 pm

RE: What's The Major Benefit Of Having Four Engines?

Sun Jan 16, 2011 5:27 am

Quoting comorin (Reply 2):
Not to mention that should you lose 2 engines you can still fly.

That is an advantage but is is largely academic. The likelihood of two unrelated engine failures is so remote it has never happened since the advent of jets.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Mir
Posts: 19491
Joined: Mon Jan 05, 2004 3:55 am

RE: What's The Major Benefit Of Having Four Engines?

Sun Jan 16, 2011 5:29 am

Pretty much the only benefit of a four-engine aircraft vs. a two-engine aircraft (assuming the same size - obviously you can make a larger four-engine aircraft than a two-engine aircraft) is improved engine-out performance. You'll climb faster and be able to cruise higher, which may open up routes that would be impossible with a twin. There are a limited number of those routes out there, and those are the routes where airlines like to operate 340s instead of 777s.

-Mir
7 billion, one nation, imagination...it's a beautiful day
 
brons2
Posts: 2480
Joined: Tue Sep 25, 2001 1:02 pm

RE: What's The Major Benefit Of Having Four Engines?

Sun Jan 16, 2011 6:03 am

Can the A343 really maintain a driftdown altitude of over 29,000 feet on 3 engines?
Firings, if well done, are good for employee morale.
 
User avatar
DocLightning
Posts: 22181
Joined: Wed Nov 16, 2005 8:51 am

RE: What's The Major Benefit Of Having Four Engines?

Sun Jan 16, 2011 9:36 pm

Quoting Starlionblue (Reply 5):
The likelihood of two unrelated engine failures is so remote it has never happened since the advent of jets.

There is a debate out as to whether the famed US flight that unexpectedly decided to become a Hudson River ferry might have survived if it had more engines. The cause was bird strikes on each engine. I'd bet that had it been a 747, it's possible that at least one engine would have survived. That would have been enough to at least get them to EWR. would have been a messy landing, but at least a dry one.

The debate is academic. The chances of a second event of the same nature are so microscopically small that it isn't even remotely sensible to ban all twins.
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan
 
User avatar
SEPilot
Posts: 5719
Joined: Sat Dec 30, 2006 10:21 pm

RE: What's The Major Benefit Of Having Four Engines?

Mon Jan 17, 2011 1:05 am

There is twice the chance of an uncontained engine failure bringing down the aircraft.   
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
 
User avatar
SEPilot
Posts: 5719
Joined: Sat Dec 30, 2006 10:21 pm

RE: What's The Major Benefit Of Having Four Engines?

Mon Jan 17, 2011 3:18 am

There is also the possibility of an inboard engine falling off, striking the outboard engine and knocking it off as well, and bringing down the aircraft. This has happened twice on 747's, while no twin has ever crashed because of an engine falling off. I did a study on engine caused crashes some time ago, and I found the exact same number of engine caused crashes on twins as on aircraft with more than two engines. Seeing as how there are far more twins than more than twins, that means that your chance of an engine caused crash is much greater on a quad or tri than a twin. Also, the only two airliner crashes that resulted in casualties that were caused by bird strikes were quads.
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
 
ThirtyEcho
Posts: 1411
Joined: Tue Jan 01, 2002 1:21 am

RE: What's The Major Benefit Of Having Four Engines?

Mon Jan 17, 2011 10:09 am

While we are at it, we could discuss the dreaded 7-engine flight in a B-52.
 
Klaus
Posts: 21642
Joined: Wed Jul 11, 2001 7:41 am

RE: What's The Major Benefit Of Having Four Engines?

Mon Jan 17, 2011 1:12 pm

Quoting SEPilot (Reply 10):
I did a study on engine caused crashes some time ago, and I found the exact same number of engine caused crashes on twins as on aircraft with more than two engines. Seeing as how there are far more twins than more than twins, that means that your chance of an engine caused crash is much greater on a quad or tri than a twin.

No, that is a false conclusion unless further qualified. In the early years of the jet age there were many more quads compared to today simply due to the level of technology. And the risks were much higher than today, also due to the maturity level of technology plus limited operational experience.

The risk profiles have changed completely over the decades. Simply ignoring these underlying factors would completely invalidate a study.

Quoting SEPilot (Reply 10):
Also, the only two airliner crashes that resulted in casualties that were caused by bird strikes were quads.

Which ones were that?
 
Max777geek
Posts: 159
Joined: Wed Mar 07, 2007 6:20 pm

RE: What's The Major Benefit Of Having Four Engines?

Mon Jan 17, 2011 3:19 pm

Quoting comorin (Reply 2):
Not to mention that should you lose 2 engines you can still fly.

Always tought that was just one out of four, not two.

Quoting Starlionblue (Reply 5):
The likelihood of two unrelated engine failures is so remote it has never happened since the advent of jets.

Dude, when it's time, it's time.

Quoting ThirtyEcho (Reply 11):
While we are at it, we could discuss the dreaded 7-engine flight in a B-52.

There's a procedure in place for that on B52 checklists. That's called "one engine what?"
 
User avatar
SEPilot
Posts: 5719
Joined: Sat Dec 30, 2006 10:21 pm

RE: What's The Major Benefit Of Having Four Engines?

Mon Jan 17, 2011 7:08 pm

Quoting Klaus (Reply 12):
No, that is a false conclusion unless further qualified. In the early years of the jet age there were many more quads compared to today simply due to the level of technology. And the risks were much higher than today, also due to the maturity level of technology plus limited operational experience.

But in the early days of jet transports there were no engine caused crashes that I could find. The numbers still stand; there have been as many engine caused crashes in tris and quads as with twins, even going back to the beginning of the jet age.

Quoting Klaus (Reply 12):
Which ones were that?

One was at BOS, I believe; an Electra was taking off and went through a flock of starlings and choked 3 engines, I believe. It crashed and I believe all were killed. The second was a DC-4 or 6 and it lost the horizontal stabilizer due to a large bird collision and crashed, again with all aboard killed.
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
 
Klaus
Posts: 21642
Joined: Wed Jul 11, 2001 7:41 am

RE: What's The Major Benefit Of Having Four Engines?

Mon Jan 17, 2011 7:15 pm

Quoting SEPilot (Reply 14):
But in the early days of jet transports there were no engine caused crashes that I could find. The numbers still stand; there have been as many engine caused crashes in tris and quads as with twins, even going back to the beginning of the jet age.

Still worthless without a specification of aircraft generation, airframe age, accident dates and the remaining factors involved.

You are claiming a correlation here, which in the absence of proper qualification of the input data is no substantial indication of causation.

Quoting SEPilot (Reply 14):
One was at BOS, I believe; an Electra was taking off and went through a flock of starlings and choked 3 engines, I believe. It crashed and I believe all were killed. The second was a DC-4 or 6 and it lost the horizontal stabilizer due to a large bird collision and crashed, again with all aboard killed.

So many decades ago (or at least ancient airframes). Goes to my point.
 
mandala499
Posts: 6600
Joined: Wed Aug 29, 2001 8:47 pm

RE: What's The Major Benefit Of Having Four Engines?

Mon Jan 17, 2011 7:22 pm

3-engined ferry anyone?????
Now I don't think I can get a single engine ferry on a twin!   

Mandala499
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
planewasted
Posts: 546
Joined: Thu Jan 17, 2008 11:47 pm

RE: What's The Major Benefit Of Having Four Engines?

Mon Jan 17, 2011 9:06 pm

Quoting Starlionblue (Reply 5):
That is an advantage but is is largely academic. The likelihood of two unrelated engine failures is so remote it has never happened since the advent of jets.

BMI92 would most probably not have crashed if the airplane had four engines.
 
User avatar
Starlionblue
Posts: 20643
Joined: Fri Feb 27, 2004 9:54 pm

RE: What's The Major Benefit Of Having Four Engines?

Mon Jan 17, 2011 11:03 pm

Quoting PlaneWasted (Reply 17):
Quoting Starlionblue (Reply 5):
That is an advantage but is is largely academic. The likelihood of two unrelated engine failures is so remote it has never happened since the advent of jets.

BMI92 would most probably not have crashed if the airplane had four engines.

That one doesn't count. BMI 92 only had one engine failure. You can't blame the airplane if the pilots shut down the good engine.


Good point DocLightning.

Quoting Max777geek (Reply 13):
Quoting Starlionblue (Reply 5):
The likelihood of two unrelated engine failures is so remote it has never happened since the advent of jets.

Dude, when it's time, it's time.

I'm not saying can't happen. I'm just saying the chance of two unrelated failures is so vanishingly remote that it doesn't really confer an advantage to quads per se. Regulators have come to the same conclusion, hence the introduction of ETOPS requirements for quads, putting them on an equal footing.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Viscount724
Posts: 19316
Joined: Thu Oct 12, 2006 7:32 pm

RE: What's The Major Benefit Of Having Four Engines?

Mon Jan 17, 2011 11:32 pm

Quoting SEPilot (Reply 14):
Quoting Klaus (Reply 12):
Which ones were that?

One was at BOS, I believe; an Electra was taking off and went through a flock of starlings and choked 3 engines, I believe. It crashed and I believe all were killed. The second was a DC-4 or 6 and it lost the horizontal stabilizer due to a large bird collision and crashed, again with all aboard killed.

Not commercial, but a USAF E-3 AWACS (707-320C airframe) crashed soon after takeoff from Elmendorf AFB near ANC in 1995 after geese were engested into engines 1 and 2. All 24 aboard were killed.
http://www.jber.af.mil/news/story.asp?id=123070056

This article includes the CVR transcript etc.
http://flightsafety.org/ap/ap_nov96.pdf

A year later a NATO E-3 AWACS was written off after ingesting birds and overrunning into the water in Greece. Fortunately no fatalities in that one.


View Large View Medium
Click here for bigger photo!

Photo © Holger Loersch



More photos here:
http://www.aviationpics.de/military/1999/awacs/awacs.html

There have been other birdstrike-related fatal accidents involving 4-engine military aircraft.
 
User avatar
SEPilot
Posts: 5719
Joined: Sat Dec 30, 2006 10:21 pm

RE: What's The Major Benefit Of Having Four Engines?

Mon Jan 17, 2011 11:53 pm

Quoting Klaus (Reply 15):
Still worthless without a specification of aircraft generation, airframe age, accident dates and the remaining factors involved.

You are claiming a correlation here, which in the absence of proper qualification of the input data is no substantial indication of causation.

I am not claiming any kind of causation. I am looking at pure numbers: number of crashes caused by the engines in jet airliners. I included every type of engine caused crash, including engines falling off, engines exploding, and everything except running out of fuel. It is surprising how few there were; as I said earlier, NONE of the first generation jetliners has EVER crashed because of the engines. Airframe age, airframe generation, and all of that is irrelevant. The sole question was did the crash occur because of the engine? If it did, how many engines did the plane have? As I have repeatedly said, there really have not been very many of them. The event that caused the most crashes was an engine falling off and causing further damage; it has happened three times, once to a DC-10 (AA191) and twice to 747's. Only once, to the best of my knowledge, has an uncontained failure caused a crash (UA232). There have been at least three cases of uncontained failures occurring on the ground; I have not included them, as I did not consider them crashes, even though two of them resulted in fatalities.

Quoting Klaus (Reply 15):
So many decades ago (or at least ancient airframes). Goes to my point.

Neither of these was in my compilation, as neither was a jet airliner. The ONLY jet airliner that has been brought down by bird strikes, to the best of my knowledge, was the US A320 in the Hudson. I did not include that one in my compilation either, as it happened after I did the research.
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
 
Klaus
Posts: 21642
Joined: Wed Jul 11, 2001 7:41 am

RE: What's The Major Benefit Of Having Four Engines?

Tue Jan 18, 2011 12:29 am

Quoting Starlionblue (Reply 18):
That one doesn't count. BMI 92 only had one engine failure. You can't blame the airplane if the pilots shut down the good engine.

"Blame" is beside the point. But resilience against technical or crew malfunctions is relevant. On a quad, the chances of recovery would likely have been much better.

Quoting Viscount724 (Reply 19):
Not commercial, but a USAF E-3 AWACS (707-320C airframe) crashed soon after takeoff from Elmendorf AFB near ANC in 1995 after geese were engested into engines 1 and 2. All 24 aboard were killed.
http://www.jber.af.mil/news/story.asp?id=123070056

This article includes the CVR transcript etc.
http://flightsafety.org/ap/ap_nov96.pdf

A year later a NATO E-3 AWACS was written off after ingesting birds and overrunning into the water in Greece. Fortunately no fatalities in that one.

1950s era aircraft. How many twins from that era are ETOPS-certified?

So far, I see my point above only confirmed.
 
Klaus
Posts: 21642
Joined: Wed Jul 11, 2001 7:41 am

RE: What's The Major Benefit Of Having Four Engines?

Tue Jan 18, 2011 12:39 am

Quoting SEPilot (Reply 20):
The ONLY jet airliner that has been brought down by bird strikes, to the best of my knowledge, was the US A320 in the Hudson.
"bird strike" fatalities - Google Search

Second link:

FATALITIES AND DESTROYED CIVIL AIRCRAFT DUE TO BIRD STRIKES, 1912 – 2002

Quote:
It is now believed that the number of fatal accidents has risen to 42 killing 231 people. In addition the total of aircraft destroyed is now 80. These are as follows:
• Airliners and Executive Jets – 10 fatal accidents killing 164 and destroying 30 aircraft.
• Aeroplanes 5,700 kg and below – 27 fatal accidents killing 58 and destroying 42 aircraft.
• Helicopters – 5 fatal accidents killing 9 people and destroying 8 helicopters.
 
Viscount724
Posts: 19316
Joined: Thu Oct 12, 2006 7:32 pm

RE: What's The Major Benefit Of Having Four Engines?

Tue Jan 18, 2011 1:00 am

Quoting SEPilot (Reply 20):
The ONLY jet airliner that has been brought down by bird strikes, to the best of my knowledge, was the US A320 in the Hudson.

Don't forget the Overseas National DC-10-30 at JFK in 1975.
http://aviation-safety.net/database/record.php?id=19751112-1

http://www.youtube.com/watch?v=1kiifVK92NA
 
User avatar
SEPilot
Posts: 5719
Joined: Sat Dec 30, 2006 10:21 pm

RE: What's The Major Benefit Of Having Four Engines?

Tue Jan 18, 2011 1:44 am

Quoting Starlionblue (Reply 18):
BMI92 would most probably not have crashed if the airplane had four engines.

That one doesn't count. BMI 92 only had one engine failure. You can't blame the airplane if the pilots shut down the good engine.

For the record, I did include this one in my compilation. The crash ultimately was caused by the engine failure; the crew screwed up, but if the engine hadn't failed the plane wouldn't have crashed.

Quoting Klaus (Reply 22):
FATALITIES AND DESTROYED CIVIL AIRCRAFT DUE TO BIRD STRIKES, 1912 – 2002

Thanks for posting this-there were several that I was unaware of. But I do not really consider bird strikes to be engine related crashes-they are their own category. This paper also shows that bird strikes tend to bring aircraft down regardless of the number of engines, as is also shown by the military crashes that others have alluded to.
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
 
Klaus
Posts: 21642
Joined: Wed Jul 11, 2001 7:41 am

RE: What's The Major Benefit Of Having Four Engines?

Tue Jan 18, 2011 1:44 am

Quoting Viscount724 (Reply 23):
Don't forget the Overseas National DC-10-30 at JFK in 1975.

Page 10 in the list above.
 
Klaus
Posts: 21642
Joined: Wed Jul 11, 2001 7:41 am

RE: What's The Major Benefit Of Having Four Engines?

Tue Jan 18, 2011 1:52 am

Quoting SEPilot (Reply 24):
This paper also shows that bird strikes tend to bring aircraft down regardless of the number of engines, as is also shown by the military crashes that others have alluded to.

Not regardless. The number of engines does make a difference, the difference is just not as big as it would be if the engines were always independently affected. In case of a flock of birds the probabilities are dependent, but even then the probability of retaining at least some thrust grows with the number of engines. So does the risk of a single-cause crash, but that one is very much smaller to begin with, nowadays even smaller than back in the days of most of the reported incidents.

As always in statistics, the actual probabilities and their dependencies (or lack thereof) will make a difference.
 
User avatar
Starlionblue
Posts: 20643
Joined: Fri Feb 27, 2004 9:54 pm

RE: What's The Major Benefit Of Having Four Engines?

Tue Jan 18, 2011 5:20 am

Quoting Klaus (Reply 21):
Quoting Starlionblue (Reply 18):
That one doesn't count. BMI 92 only had one engine failure. You can't blame the airplane if the pilots shut down the good engine.

"Blame" is beside the point. But resilience against technical or crew malfunctions is relevant. On a quad, the chances of recovery would likely have been much better.

Certainly on a quad they would most likely have made the runway.

However an incompletely trained crew on type (they had Jurassic experience but their training on the Classic was woefully incomplete) is a danger regardless of number of engines. Add to that the fact that they interrupted their review of the engine instruments due to an ATC call and did not finish it. Sadly, that very review would eventually have gotten them to the vibration indicator that showed which engine was at fault clearly. The crew was fired for cause after the accident report.

A sufficiently determined crew will manage to crash any aircraft, regardless of envelope protection, number of engines and so forth.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
411A
Posts: 1788
Joined: Mon Nov 12, 2001 10:34 am

RE: What's The Major Benefit Of Having Four Engines?

Tue Jan 18, 2011 6:11 am

The major benefit of having three or four engines versus only two, is those routes that are simply not suitable for a twin, without an exemption.
Example.
CPT-EZE, 3730 nautical miles, with NO diversion enroute alternates.
This route can be approved for a twin engined airplane (with an exemption), however, so far as I know, it is not.
Having flown this route many times with L1011 aircraft recently, the CPT-EZE sector is many times eleven hours, westbound....all overwater.
 
Klaus
Posts: 21642
Joined: Wed Jul 11, 2001 7:41 am

RE: What's The Major Benefit Of Having Four Engines?

Tue Jan 18, 2011 6:29 am

Quoting Starlionblue (Reply 27):
A sufficiently determined crew will manage to crash any aircraft, regardless of envelope protection, number of engines and so forth.

One of the main points of aircraft design is to raise the required level of determination beyond what most crews will attain. If it wasn't so, all technical precautions would be useless.
 
tdscanuck
Posts: 8573
Joined: Wed Jan 11, 2006 7:25 am

RE: What's The Major Benefit Of Having Four Engines?

Tue Jan 18, 2011 7:23 am

Quoting 411A (Reply 28):

The major benefit of having three or four engines versus only two, is those routes that are simply not suitable for a twin, without an exemption.

With the rewrite of the ETOPS rules in 2007, I don't think that's true anymore. There's going to be a hole beyond the 180-minute radius on CPT-EZE, which is where you now have to do ETOPS whether you're a twin, tri, or quad (if you're a Part 121 carrier).

Tom.
 
Max777geek
Posts: 159
Joined: Wed Mar 07, 2007 6:20 pm

RE: What's The Major Benefit Of Having Four Engines?

Tue Jan 18, 2011 8:16 am

Quoting mandala499 (Reply 16):
3-engined ferry anyone?????
Now I don't think I can get a single engine ferry on a twin!

That's allowed I don't think so. That's possible I do.
 
411A
Posts: 1788
Joined: Mon Nov 12, 2001 10:34 am

RE: What's The Major Benefit Of Having Four Engines?

Tue Jan 18, 2011 10:09 am

Quoting tdscanuck (Reply 30):
With the rewrite of the ETOPS rules in 2007, I don't think that's true anymore.

If that were true, direct airline flights between those two cities would not exist any longer.
However, we can see that direct scheduled and charter airline flights certainly continue, with three or four engine aircraft, on a daily basis.
So much for your suppossion.
 
User avatar
Starlionblue
Posts: 20643
Joined: Fri Feb 27, 2004 9:54 pm

RE: What's The Major Benefit Of Having Four Engines?

Tue Jan 18, 2011 10:37 am

Quoting Klaus (Reply 29):
Quoting Starlionblue (Reply 27):
A sufficiently determined crew will manage to crash any aircraft, regardless of envelope protection, number of engines and so forth.

One of the main points of aircraft design is to raise the required level of determination beyond what most crews will attain. If it wasn't so, all technical precautions would be useless.

Fair point. And in fact the 737 Classic instrumentation, with tiny tiny dials, was found to be part of the problem. But I still don't think it is fair to blame the aircraft. If the air crew had received the proper training they would likely have made the runway.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Klaus
Posts: 21642
Joined: Wed Jul 11, 2001 7:41 am

RE: What's The Major Benefit Of Having Four Engines?

Tue Jan 18, 2011 11:03 am

Quoting Starlionblue (Reply 33):
But I still don't think it is fair to blame the aircraft.

Which I've explicitly declined to do above.

But risk assessment is not a matter of fairness – it simply looks at the number of paths towards disaster and the probabilities assigned to each one.

And for this particular scenario considered by itself a quad would just have had a substantially lower aggregate probability.

Quoting Starlionblue (Reply 33):
If the air crew had received the proper training they would likely have made the runway.
or if the aircraft had had more engines
or if both conditions had been combined.
 
User avatar
Starlionblue
Posts: 20643
Joined: Fri Feb 27, 2004 9:54 pm

RE: What's The Major Benefit Of Having Four Engines?

Tue Jan 18, 2011 1:17 pm

I see where you are coming from now. Interesting.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
tdscanuck
Posts: 8573
Joined: Wed Jan 11, 2006 7:25 am

RE: What's The Major Benefit Of Having Four Engines?

Tue Jan 18, 2011 2:38 pm

Quoting 411A (Reply 32):
If that were true, direct airline flights between those two cities would not exist any longer.

It wouldn't prevent direct flights, it just changes the fuel planning. The major change for tri/quad jets in the rewrite was to impose ETOPS fuel/diversoin/operational planning onto all aircraft beyond 180-minute ETOPS, rather than just twins. Provided you've got the right fuel/infrastructure/planning in place, there's nothing wrong with the route.

Of course, anyone flying CPT-EZE probably isn't flying under an FAA operating certificate, so they wouldn't have to follow the 2007 FAA rewrite until the revisions trickle down to all the national regulators (at least, those that choose to adopt the change).

Tom.
 
tom355uk
Posts: 168
Joined: Sat Nov 03, 2007 11:34 pm

RE: What's The Major Benefit Of Having Four Engines?

Thu Jan 20, 2011 4:48 pm

Quoting Max777geek (Reply 31):
Quoting mandala499 (Reply 16):
3-engined ferry anyone?????
Now I don't think I can get a single engine ferry on a twin!

That's allowed I don't think so. That's possible I do.

Not this again.......

  

There's nothing in the rules that says you can't, but it wouldn't be approved by any regulator if you asked them, right? 
on Twitter @tombeckett2285
 
tdscanuck
Posts: 8573
Joined: Wed Jan 11, 2006 7:25 am

RE: What's The Major Benefit Of Having Four Engines?

Fri Jan 21, 2011 1:29 am

Quoting tdscanuck (Reply 36):
There's nothing in the rules that says you can't, but it wouldn't be approved by any regulator if you asked them, right?

Short answer from the long thread: it won't be approved now but it has been approved in the past.

Tom.

Who is online

Users browsing this forum: vhqpa and 26 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos