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Saving Fuel Long-haul: Onestop Or Nonstop?  
User currently offlineKevin777 From Denmark, joined Sep 2006, 1165 posts, RR: 1
Posted (6 years 3 months 1 week 2 days 15 hours ago) and read 3563 times:

Hi all..

With Thai discontinuing the nonstop to NYC, and cutting back on LAX, long-haul travel, and ultra long-haul in particular, has taken a punch. AFAIK SQ and other airlines (CX, AC, EK etc.) have yet no plans to discontinue their ultra long-haul services, but obviously these services aren't doing too good at all with oil prices of today. If it ever were within reach, a SYD-LHR nonstop seems even more out of reach now, and "traditional long" long-haul services between Europe and Western US / Far East are being cut back in general.

My question is: How does the cost/benefit calculation work for maximizing fuel savings trading between long-haul nonstop and onestop? And to what extend does the new high oil price influence this?

Obviously, the longer the flight, the more fuel saved per mile for take-off, climb and landing - however, the longer the flight, the more fuel you have to use to transport fuel for the later parts of the journey. But where is the optimal balance? On top of this there are other considerations: A nonstop ULH flight attracts high-yield ptp traffic, while a onestop might be able to offer more frequencies because of the added volume taken in via the stop. A onestop can carry more pax whereas a ULH flight will often be pax and indeed cargo restricted.

So where is the optimal balance? Could we in the future see more onestops, also on the not ultra-long long-hauls? A revival of stopping in the Middle East en route to Asia from Europe? Tech-stops in ANC between California and Japan? More use of tech-stops in general (as opposed to "real" stops with on/off traffic), like European charter airlines are doing a lot to Asia with 757 and 767s?

Looking only at fuel economy, how much fuel, if any, would TG save by going down in, say, ANC, on the way to the U.S.? How many extra pax / extra cargo could they carry?

Where is the (new) optimal balance?

Best regards from CPH,

Kevin777  Smile


"I was waiting for you at DFW, but you must have been in LUV" CPH-HAM-CPH CR9
16 replies: All unread, jump to last
 
User currently offlineXT6Wagon From United States of America, joined Feb 2007, 3409 posts, RR: 4
Reply 1, posted (6 years 3 months 1 week 2 days 14 hours ago) and read 3545 times:

It depends alot on the plane, and the payload for a route which is better.

The better a plane is at fuel efficency in cruise the longer non-stop route it can make more money than a one stop.

The better a plane is at fuel effienency in climb, the shorter a flight can be for a non-stop to be profitable.

The higher the ticket premium for a non-stop flight, the longer the route that it can be more profitable

Also there is a nice "wall" where routes over a certain lengh are much better to do as 1 stops given that they require 2 full sets of crew on a non-stop to accomplish the non-stop. Which is a payload penalty if not a crew cost penalty.

It gets more complicated if you decide to factor in passengers leaving/getting on at the middle airport, or high landing fees.


User currently offlinePanais From Cyprus, joined May 2008, 463 posts, RR: 0
Reply 2, posted (6 years 3 months 1 week 2 days 14 hours ago) and read 3498 times:

How about this idea?

For a 16-hour flight, you use an Airbus A330-300 instead of a 777-200LR.

The A330-300 makes a stop somewhere in the middle for re-fuelling and probably re-stocking. For the 45 - 60 minute stay, the midway airport, offers access to a store/cafe/dutyfree/rest area for that A330-330 flight only. (makes it easier to direct everybody back to the plane and do not need another security check.)

The A330-300 might burn more fuel, because of the additional landing and take off, (which I question) but it will make more money on:
1. The extra cargo it can carry instead of fuel
2. The extra passengers since the flight can be packed as much as possible.
3. The extra revenue of people spending at the airport, or the airport not charging any landing fees. (just ask Dubai International Airport, how much money their duty free shops make)

Besides, passengers in economy would like the idea of streaching midway, instead of being stuck in planes whose seats seem to be getting smaller.


User currently offlineKevin777 From Denmark, joined Sep 2006, 1165 posts, RR: 1
Reply 3, posted (6 years 3 months 1 week 2 days 11 hours ago) and read 3327 times:



Quoting XT6Wagon (Reply 1):
Also there is a nice "wall" where routes over a certain lengh are much better to do as 1 stops given that they require 2 full sets of crew on a non-stop to accomplish the non-stop. Which is a payload penalty if not a crew cost penalty.



Quoting XT6Wagon (Reply 1):
Also there is a nice "wall" where routes over a certain lengh are much better to do as 1 stops given that they require 2 full sets of crew on a non-stop to accomplish the non-stop. Which is a payload penalty if not a crew cost penalty.

What's the wall here? 14 hours or something..? Different legal constraints / union constraints in different countries?

Quoting Panais (Reply 2):
How about this idea?

I think the idea is all right, although I donøt think you'd be able to get people on, off and go shopping within 45 minutes, we're more looking at two hours here - but what if you made a really short and simple stop, ONLY to refuel, nothing else. The pilots would come out of the plane, make their go around the bird while it's being filled up, and they leave within 15 minutes. Not much of a delay compared to nonstop; in practice just a nonstop with a mid-air re-fuelling on the ground, and much higher payload - I think it could work.. (?)

Kevin777  Smile



"I was waiting for you at DFW, but you must have been in LUV" CPH-HAM-CPH CR9
User currently offlineManchesterMAN From United Kingdom, joined Sep 2003, 1227 posts, RR: 1
Reply 4, posted (6 years 3 months 1 week 2 days 11 hours ago) and read 3273 times:

I would think traffic rights play a role here as well. It is surely more profitable for an airline to fly LHR-SIN-SYD than LHR-SYD non stop if the carrier has traffic rights on all sectors. As well as carrying LHR-SYD pax the carrier can also carry LHR-SIN and SIN-SYD pax. Yields LHR-SIN are not that much lower than LHR-SYD and then you get a whole bunch of new fare paying pax for SIN-SYD. To match the revenue gained from the stop you would have to charge such a premium for non-stop that it would discourage pax from flying non stop. Of course it depends on whether the extra revenue of stopping outweights the cost. According to TG it does.


Flown: A300,A319,A320,A321,A330,A340.A380,717,727,737,747,757,767,777,DC9,DC10,MD11,MD80,F100,F50,ERJ,E190,CRJ,BAe146,Da
User currently offlineBurkhard From Germany, joined Nov 2006, 4397 posts, RR: 2
Reply 5, posted (6 years 3 months 1 week 2 days 10 hours ago) and read 3174 times:

Once I went from AMS to LIM on a KLM MD11, we had such a stop in Aruba, and it was just pleasant to have 50 minutes ground under the feet, nice life caribic music, and nobody worried about security or such crap invented by state terrorists. OK, Aruba is part of the Netherlands, or was at least for that purpose.

User currently offlineBurkhard From Germany, joined Nov 2006, 4397 posts, RR: 2
Reply 6, posted (6 years 3 months 1 week 2 days 10 hours ago) and read 3167 times:

Thinking again about it, some airports could even specialize on this - as some did in Super Conny times...

User currently offlineNAV20 From Australia, joined Nov 2003, 9909 posts, RR: 35
Reply 7, posted (6 years 3 months 1 week 2 days 10 hours ago) and read 3111 times:

The first time I saw my father off on a flight to Bahrain it was on a Britannia that stopped at Rome and Beirut on the way. The first time he went to New York it was on a Comet that would 'probably' have to land to refuel at Gander - he was delighted that they had favourable winds and got there direct.

The first time I went to the USA myself (from Heathrow) we went direct to Chicago in a 707. Not much later I got accustomed to London-Singapore-Melbourne - and soon afterwards Melbourne-Los Angeles - in 747s.

I think 'effective ranges' will continue to 'creep up' - as they always have. It's only a matter of time before Qantas achieves its 'Holy Grail' - Sydney-London nonstop. And possibly Sydney/Melbourne direct to New York even before that. At first for premium passengers, later for the rest of us (the 'herd'  Smile).

Oddly enough, I think that the recent hike in fuel prices might actually 'help' in a way. As far as I know airliners use 10 per cent of their fuel in the climb out - and they definitely use oodles of time letting down and landing to refuel (and then have to climb OUT all over again).

It'll happen - only question is when......



"Once you have flown, you will walk the earth with your eyes turned skywards.." - Leonardo da Vinci
User currently offlineJustapassenger From United States of America, joined Dec 2004, 95 posts, RR: 0
Reply 8, posted (6 years 3 months 1 week 2 days 7 hours ago) and read 2987 times:

Maybe the guys at CO can shed some light on this from their Berlin-EWR experience. I know that the occasional refueling stops westbound are always blamed on the winds, but are there times when the refueling stop is really made in order to accommodate an extra heavy load of passengers or cargo? If so, does the extra revenue overcome the extra costs of refueling? Are there times when a heavily loaded flight with a refueling stop is more profitable than an at-capacity non-stop from Berlin to Newark? Since the regular passengers on this flight are probably aware of the possibility of a refueling stop on the way to Newark, CO could probably sneak in an occasional refueling stop for profit reasons rather than weather reasons without inconveniencing the passengers enough to impact repeat business.

User currently offlineKevin777 From Denmark, joined Sep 2006, 1165 posts, RR: 1
Reply 9, posted (6 years 3 months 1 week 2 days 1 hour ago) and read 2693 times:



Quoting NAV20 (Reply 7):
Oddly enough, I think that the recent hike in fuel prices might actually 'help' in a way. As far as I know airliners use 10 per cent of their fuel in the climb out - and they definitely use oodles of time letting down and landing to refuel (and then have to climb OUT all over again).

Well, that really depends on the distance - for short flights, yes, maybe, but I doubt that a 747 going LHR-HKG spends 10 % of the fuel (close 10.000 litres or so) just to reach cruising altitude. But again, fuel-wise it depends on the costs of:

Onestop: Two climbs, two landings, extra taxi, deviation from straight flightpath - yet flying the first leg without having to carry fuel for the second.

Nonstop: One climb, one landing, straight flightpath - yet having to carry all fuel with you from the origin, that in itself guzzling more fuel.

On top of this, there are all the other considerations - extra traffic if onestop, higher yields if nonstop, higher payload if onestop, lower fuel-bill (??? or??) if onestop/nonstop??

What would - fuel-wise ONLY - be most optimal (given exact same payload): HKG-LHR nonstop or onestop?

Quoting NAV20 (Reply 7):
It'll happen - only question is when......

Hmmm.... I doubt that LHR-SYD will become a reality anytime soon.. I could see a 777 or a 346 (or maybe an all-J single-aisle LR-jet??) doing LHR-SYD with a brief, 45-minute no-one-leaves-the-plane tech-stop somewhere on the straight flightpath - this would only increase flying time marginally, while reducing fuel costs, increasing payload and cutting away extra crew.

Quoting Justapassenger (Reply 8):
but are there times when the refueling stop is really made in order to accommodate an extra heavy load of passengers or cargo?

Well, I know that back when SK did HKG-CPH with 767-300ERs, they often faced a choice westbound: Either go down and refuel in PEK on the way, or leave some cargo on the tarmac in HKG and go nonstop - AFAIK they did both things, depending on the situation for the specific departure.

Quoting Justapassenger (Reply 8):
Are there times when a heavily loaded flight with a refueling stop is more profitable than an at-capacity non-stop from Berlin to Newark?

Well, BER-EWR, an 8-hour flight westbound or something like that, isn't long enough for this I would think - but for the sake of argument, say, BER-LAX might not be totally off if refuelling somewhere in Canada (or maybe SFJ) and increasing payload while reducing fuel costs (maybe)?

Kevin777  Smile



"I was waiting for you at DFW, but you must have been in LUV" CPH-HAM-CPH CR9
User currently offlineIncitatus From Brazil, joined Feb 2005, 4014 posts, RR: 13
Reply 10, posted (6 years 3 months 1 week 2 days ago) and read 2625 times:

I looked at this issue recently and a 777-200ER doing a 1-stop 9h+9h trip would burn less fuel than a similarly loaded 777-200LR doing a nonstop 18h trip.

There are other costs to be looked at in the calculation, such as crew time and the cost of landing fees at the internediate stop. Overall it is likely a close call for those two scenarios.



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User currently offlineOsiris30 From Barbados, joined Sep 2006, 3192 posts, RR: 25
Reply 11, posted (6 years 3 months 1 week 2 days ago) and read 2576 times:



Quoting Incitatus (Reply 10):
There are other costs to be looked at in the calculation, such as crew time and the cost of landing fees at the internediate stop. Overall it is likely a close call for those two scenarios.

Cycles on the airframe, engine maintenance wear and tear, increased risk of accident (how often does an accident occur in the air vs. landing/take off), plus the things you mentioned including landing fees, crew time, (possible) additional fuel contracts, etc.



I don't care what you think of my opinion. It's my opinion, so have a nice day :)
User currently offlineComorin From United States of America, joined May 2005, 4896 posts, RR: 16
Reply 12, posted (6 years 3 months 1 week 1 day 22 hours ago) and read 2472 times:



Quoting Kevin777 (Reply 9):
What would - fuel-wise ONLY - be most optimal (given exact same payload): HKG-LHR nonstop or onestop?

Kevin, the Breguet Range Equation, known to all aeronautical engineers, can help you. While my mind has rusted out, there are a quite a few young bright minds on a.net that can answer your question.

What you do is to solve for fuel burnt Wmax - Wto for the two cases.

Case 1 is solve for fuel weight needed for max range.
Case 2 is solve for fuel weight to mid-point and multiply by 2.

An easier way might be to just use range charts to figure out the above. I was thinking that the same logic applies to filling up your car for a long trip, versus stopping on the way with half-tank fills.

This thread should be in Tech Ops for more in-depth answers.

Corrections welcome by practicing aeronauts!


User currently offlineXT6Wagon From United States of America, joined Feb 2007, 3409 posts, RR: 4
Reply 13, posted (6 years 3 months 1 week 1 day 22 hours ago) and read 2468 times:



Quoting Kevin777 (Reply 3):
What's the wall here? 14 hours or something..? Different legal constraints / union constraints in different countries?

Yah, no way to state it exactly. I'd say assuming 12-14 hours is a good window for when that headache pops up.


User currently offlineJbernie From Australia, joined Jan 2007, 880 posts, RR: 0
Reply 14, posted (6 years 3 months 1 week 1 day 21 hours ago) and read 2437 times:

Isn't there also a need to factor in cruise speed vs fuel burn? ie if you can fly at max cruise speed with a full load and have one stop you could potentially get there quicker than with a different aircraft type that has a lower cruise speed to conserve fuel.

Then you also have to play in what aircraft you have available in your fleet.

Porbably more than a few crazy calculations in existance to figure all this out.


User currently offlineKevin777 From Denmark, joined Sep 2006, 1165 posts, RR: 1
Reply 15, posted (6 years 3 months 1 week 1 day 4 hours ago) and read 2196 times:



Quoting Comorin (Reply 12):
Kevin, the Breguet Range Equation, known to all aeronautical engineers, can help you.

Thanks, looked it up on the INternet, there seems to be various derivatives of it for various types of operations..

Quoting Jbernie (Reply 14):
Porbably more than a few crazy calculations in existance to figure all this out.

Indeed.. Just summing up a little the factors you need to take into consideration onestop vs nonstop..:

Fuel consumption cruising and T/O + landing, payloads, better product nonstop, more volume onestop, stress on the airframe and extra wear and tear onestop, idle crew nonstop, landing fees, deviation or not from direct flightpath etc. etc...

Regards,

Kevin777



"I was waiting for you at DFW, but you must have been in LUV" CPH-HAM-CPH CR9
User currently offlineArgonaut From UK - Scotland, joined Dec 2004, 422 posts, RR: 1
Reply 16, posted (6 years 3 months 1 week 1 day 1 hour ago) and read 2095 times:



Quoting Justapassenger (Reply 8):
the guys at CO can shed some light on this from their Berlin-EWR experience. I know that the occasional refueling stops westbound

As a matter of idle interest, where does CO usually make these refuelling stops when they turn out to be necessary?



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