four engines rather than twins

[contact-landing]

why do freight companies tend to operate four engine aircraft rather than twins, even though they carry the same load ?:confused:

[boredcounter]

Hull price? Unless buying factory fresh

[Intruder]

Which twin carries the same load as a 4-engine?

[aviatorhi]

As a side note, 3 or 4 engine aircraft have better performance figures for maximum loads out of high/hot environments as well as shorter runways than your average 10000+ foot one at the major hubs. Having 3 or more engines also removes the necessity for having/maintaining ETOPS capability.

[K9nads]

Also freighters tend to operate to a variety of destinations, some are remote and not well equipped, and in the event of engine problems it is a great advantage (cheaper) for a 4 engine aircraft to 3 engine ferry to a maintenance base.

[CargoOne]

why do freight companies tend to operate four engine aircraft rather than twins, even though they carry the same load ?

Because 747 happened to be 4 engine, and MD11 happened to be 3 engine. All other advantages are very much secondary and would never seriously influence decision making, like 3-engine ferry capability etc. Would 747 be twin engined, freight companies would tend to operate twins.

777F just entered the market so in 10-15 years this will change.

[Intruder]

The MD-11 and 747 don't carry the same load, though...

[grounded27]

The MD-11 and 747 don't carry the same load, though...


The B777 had to have a few modifications to it to be able to carry the same load and be more efficient as the MD-11 like 2 115k thrust engines as opposed to the 2 90k engines on the original -200. The MD-11 has 3 62k engines and as stated above can be easily ferried with one out.

[contact-landing]

Well thanks people,

Got this question from an interview preparation booklet and I think the above is good feedback...:D

happy flying.

[an3_bolt]

Does anyone actually do 3 engine ferry in 4 engine aircraft these days?

Last attempt I heard of was an "Asian" carrier attempting it and ending up very quickly in the grass:{ (and that was quite some time ago).

[8029848s]

BA does regularly with its 747-400s. Once or twice a year.

No big deal.

Captain has to be qualified 3- Eng Ferry, which is a few hours in the sim and a bit of reading.

Only legislative issue is some countries will not allow you to operate from certain airports / runways.

ATB

Pete

[SMOC]

Same with CX, maybe once or twice a year, majority have the freighters deliver a fresh engine.

[Caboclo]

Even DC-6s still 3 engine ferry.

[argon18]

Still 3 engine ferry the Electra on the rare occasion an engine gets toasted.

JetPhotos.Net Photo » G-LOFE (CN: 1144) Atlantic Airlines Lockheed L-188C Electra by Tiago Palla (http://www.jetphotos.net/viewphoto.php?id=6942834&nseq=81)

[SMT Member]

The B777 had to have a few modifications to it to be able to carry the same load and be more efficient as the MD-11 like 2 115k thrust engines as opposed to the 2 90k engines on the original -200. The MD-11 has 3 62k engines and as stated above can be easily ferried with one out.

Actually if you want to compare the 777F with anything, you'd be better off with a 747-400BCF. Both are able to lift around 107 tons, but the 777F can carry the load further. Given a similar load, say 75 tons, the B747-400F will burn 140ish tons on a specific Far East - Europe route. On the same route, on the same day, a B777F carrying the same 75 tons burned 100ish tons. And therein lies the reason why the B777F is the best thing since sliced bread in long-haul cargo, as long as you can live without a nose-door.

[Intruder]

Why would you compare a 777F with a 747 conversion? Why not compare it with a 747F?

I'm not so sure that the 777F does all that is claimed for it, now that Thai cancelled their 777F contract with Southern Air...

[Fr8Dog]

Also, the new -8 74 burns LESS fuel (over 400 gallons less per hour) than the 777 and carries a significantly larger payload. Not to mention that e-tops does not come into play, and if you loose an engine you sill have 3 over the middle of the pond! If I am going across the Pacific or the Atlantic I want 4 engines thank you very much!!

[SMT Member]

Why would you compare a 777F with a 747 conversion? Why not compare it with a 747F?

I'm not so sure that the 777F does all that is claimed for it, now that Thai cancelled their 777F contract with Southern Air...

Cause it makes no more sense than comparing it with the MD11. As for Thai and their relationship with Southern and the B777, I have no idea why Thai pulled out. I know why Air France tried to ditch theirs, and that was poor homework. What I do know is that FedEx cannot get enough of them, and that the experience AeroLogic has had with theirs was, at least partly, the reason why LH Cargo went and bought a few. I also know that the aircraft actually does more than the original brochure numbers, which is quite a surprise indeed. Later iterations have seen further improvements, and it is not unlikely we will see 108 tons payload in the future.

Also, the new -8 74 burns LESS fuel (over 400 gallons less per hour) than the 777 and carries a significantly larger payload. Not to mention that e-tops does not come into play, and if you loose an engine you sill have 3 over the middle of the pond! If I am going across the Pacific or the Atlantic I want 4 engines thank you very much!!

Not sure I buy the bit about the dash 8 burning less than the B777F, would be delighted to be proved wrong if you can post numbers from a reliable source. As for ETOPS, that is quickly becoming irrelevant since all aircraft will have to comply with EROPS requirements. Do agree on the last bit though, but would consider 6 engines if given the choice ;)

[Desert185]

Maybe I'm old, but four engines with a PFE onboard is my preference. Nice to have the A&P qualified PFE when you need him for a mechanical at some third world, watering hole charter destination.

[Fr8Dog]

Maybe I'm old, but four engines with a PFE onboard is my preference. Nice to have the A&P qualified PFE when you need him for a mechanical at some third world, watering hole charter destination.

Obviously a man with very good sense above!

As for FedEx wanting more 777's, remember that Fedex and UPS both carry small packages for the bulk of their load. Therefor, they cube out the aircraft way before they have to worry about weight.

As for the numbers on the -8, I was in a meeting three weeks ago with the V/P of flight operations. The number that was given is 437 gallons less per hour than the 777 so I think they must know if they are being that specific. Seeing that we have over 20 -8's either on order or optioned, I think that Boeing is giving us real numbers.

[a300dave]

I remember when I was line training on the Electra as an FE. I asked my 'Old school' instructor if he wanted to fly the A300. His answer: I only fly a four engined aircraft cause they don't make one with five!

[sodapop]

Many companies choose 747s over 777 due to the size of cargo it can carry. 777s are able to carry (mostly) standard container size freight while 747s, with the added height in the main cabin and nose-door option on "true" freighters, can carry longer or higher freight and charge a premium to do it.

[G&T ice n slice]

Can't get my brain around -8 being more fuel efficient than 777.

If this was the case surely no-one would be ordering 777s - P nor F

[Supernumerary]

i'm sure the GEnx burns reasonably less fuel than the GE90-110, but four GEnx's vs. two GE90's? dunno :hmm: .......

[Intruder]

Cause it makes no more sense than comparing it with the MD11. As for Thai and their relationship with Southern and the B777, I have no idea why Thai pulled out. I know why Air France tried to ditch theirs, and that was poor homework. What I do know is that FedEx cannot get enough of them, and that the experience AeroLogic has had with theirs was, at least partly, the reason why LH Cargo went and bought a few. I also know that the aircraft actually does more than the original brochure numbers, which is quite a surprise indeed. Later iterations have seen further improvements, and it is not unlikely we will see 108 tons payload in the future.

Why does a 777/MD11 make more sense? The MD11 doesn't have the capacity of the 777, and probably can't come close to the range of a 777 with a lighter load...

FedEx hauls mainly small packages, not heavy freight. AeroLogic does the same for DHL. I don't know what LH's plans are.

The package and freight markets are significantly different. As others have already pointed out, there is significant advantage with the 744F for heavy/outsize freight. The 744 can carry 108T HKG-ANC now, and lighter loads to 7600+ NM (e.g., 45T HKG-CVG).

[SMT Member]

Why does a 777/MD11 make more sense? The MD11 doesn't have the capacity of the 777, and probably can't come close to the range of a 777 with a lighter load...

FedEx hauls mainly small packages, not heavy freight. AeroLogic does the same for DHL. I don't know what LH's plans are.

The package and freight markets are significantly different. As others have already pointed out, there is significant advantage with the 744F for heavy/outsize freight. The 744 can carry 108T HKG-ANC now, and lighter loads to 7600+ NM (e.g., 45T HKG-CVG).

Think you misunderstood me - my point is it doesn't make sense comparing the 777 with the MD11.

AeroLogic is flying for LH now on their week-end trunk routes to the US and Far East, and the aircraft seems to be doing the job they're asking of it.

As for the last bit, so can a 777F (if you consider 107.5 tons near enough). Except it would probably be able to haul closer to 55T HKG-CVG, and it wouldn't be fuel limited.

... and I'm still not convinced 4 x GENx will burn less than 2 x GE90. That would as good as make the 777F obsolete, whereas in reality it's selling pretty damn good.

[742]

... and I'm still not convinced 4 x GENx will burn less than 2 x GE90. That would as good as make the 777F obsolete, whereas in reality it's selling pretty damn good.

In theory a quad will be more efficient in long haul operations since the engines can be sized for cruise rather than the engine failure/takeoff scenario. The A330/A340 and 777 have certainly muddied the case, but it is a mistake to assume that a twin is inherently more fuel efficient than a quad. It will be interesting to see what the final 747-8 numbers look like.

And it is also a mistake to seek a one airplane wins answer. Freight is complex, and different airplanes are going to be better fits for different routes, markets and operators. Some operators are clearly very happy with the 777, some appear to not be. And I work for one that took a very, very hard look at the 777F and then signed for the 747-8.

[Tank2Engine]

... and I'm still not convinced 4 x GEnx will burn less than 2 x GE90. That would as good as make the 777F obsolete, whereas in reality it's selling pretty damn good. Perhaps those GEnx's will burn more fuel, but what about the extra payload that a 74-8 will haul? Take a look at the big picture, not just the FF/Hr per engine.

Actually if you want to compare the 777F with anything, you'd be better off with a 747-400BCF. Both are able to lift around 107 tons, but the 777F can carry the load further. Given a similar load, say 75 tons, the B747-400F will burn 140ish tons on a specific Far East - Europe route. On the same route, on the same day, a B777F carrying the same 75 tons burned 100ish tons. And therein lies the reason why the B777F is the best thing since sliced bread in long-haul cargo, as long as you can live without a nose-door. Comparing a 747-400 Boeing Converted Freighter with a 777F (factory build freighter) is comparing apples and oranges and a bit unrealistic IMHO. Of course the 777F will win, it will win hands down because the converted 744 will have a higher DOW and a lower MTOW compared to a factory build 744F.

Comparing a 744F with a 777F (both factory build full freighters) will give a far more reasonable, although still unbalanced, picture, with a 744F hauling a payload of roughly 90 tons and requiring a block fuel of 145 tons to SE Asia. Assuming the 75 tons load and 100t fuel for the 777F that comes down to ±1350 kg of fuel to carry 1 ton, versus the 744F's ±1600 kg fuel per ton payload. Granted, the 777 is a wonderful machine and at the moment has the better fuel consumption (not payload) than the 744F, but again let's be fair, the 777 is a much newer design with next generation engines, sleek wing, raked wingtips, FBW etc.

I'm curious to see how the 74-8 will perform versus the 777F. Will it be able to deliver larger 747 size loads with lean 777 style fuel flows? Will there be a market for these kind of loads? The future will tell... ;)

[SMT Member]

T2E

On your example Europe to SE Asia. The 777F can haul max. payload (107.5) up to 10.5 hours of flight. You'll therefore find that the 777F is also able to haul 90 tons, and will burn around 105 tons getting it there. Makes the fuel burn per kg. of freigh carried even better than in your example.

Do agree, there's no single answer to what's best. But if you can live without a nose-door, the 777F will - at present - deliver the biggest bang for the buck.

[grounded27]

As I read the above comments, twin v/s quad is still the same market wise. The 748 dominates in heavy lift and the 777f dominates in volume pound per mile value. Two different markets. None the less as for freight on long sectors, if it ain't Boeing it ain't going. For the freight market.

[Tank2Engine]

SMT Member, thanks for your info! Spectacular numbers indeed for a twin! :cool:

[Arfur Dent]

What a splendid, thoughtful, polite and informative thread by all concerned. Well done chaps! Breath of fresh air so good for you!:D