Yeah ok i need to make the point i thought was obvious.

UV as well as ionizing radiation are the same per hour no matter the total length of the flight.
So unless ultra long haul makes pilots sit in the cockpit longer PER MONTH it just has nothing to do with this thread.

Also i guess they should just be offering free Aspirin prior to these long flights might cut the DVT rates significantly.

I flew the TG BKK-LAX route a couple of times on the A340-500, enjoyed it. My recollection is that the fuel costs were the problem. Are the fuel costs for the same number of people reduced for the same route with the A350 based on the magic of modern technology and number of engines? If so, I can imagine a non-stop out of Singapore or another hub making a lot more sense to people who just want to get it over with in one go.

Just The issue is around how long crews spend at higher cruise altitudes over the period of a month. With more 787's, etc. at FL410/430, exposure at that altitude has to be more than at FL350. Exposure on shorter sectors where the aircraft spends more time at lower levels or on the ground is not as serious..

IG

Does anyone know whether the A359ULR is planned to cruise at higher levels than the standard A359?

Acceptable by management or paying passenger?

I've done the Europe to Oz trip more times than I care to remember. Each trip I had to disembark go through the whole rigmarole of collecting my precious things and then after killing an hour doing nothing, get back on and reacquaint myself with all the silly nonsense I had the first time. Another cabin briefing, another crew telling me how delighted they are to have me on board, another enroute/destination weather report...etc, etc.
Just get me there please!!!
Bring it on I say again.

One of the (unintentionally funniest things I've seen on long distance travel was Richard Quest breathlessly and enthusiastically interviewing punters on the inaugural SQ A340-500 SIN-EWR flight ..
As the flight progressed they were less and less inclined to speak to RQ until at the end of the 18 hour ordeal, pax after pax hurriedly brushed past him, desperate to get off the flight. Quest was desperately trying to get someone to talk to him, a few words from a seasoned traveler...but no. Not a peep.

Quote from Bankokian..... . My recollection is that the fuel costs were the problem. Are the fuel costs for the same number of people reduced for the same route with the A350 based on the magic of modern technology and number of engines?

Does anyone know what the relative fuel costs are for one-stop vs. non-stop flights.? I can imagine that flying directly over an intermediate airfield at FL 400 will use less fuel than descending then climbing from that airfield... but... Obviously the non-stopper has to carry about twice as much fuel in the first place.
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The tankering vs refuelling trade-off isn't straightforward, particularly where ultra long haul sectors are involved.

Have a read of this thread: ULH flights burn much more fuel

Scifi

Once, long before I retired and still had the data, I calculated the fuel burn penalty of one 8000nm vs 2 x 4000nm as about 10%.

Take into account that posters suggest a seat needs to occupy 20% more floor space to be acceptable ....and all the ULH problem is there ...

Thanks Oldchina, so that is 10% more cost for the fuel, but a saving of chargeable time, and intermediate Landing Fees, which could be financially crippling if the intermediate airfield was London Heathrow.
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Though of course cost is only one side of the equation.

Flying non-stop and having to carry all that extra fuel from the origin airport could result in being payload-limited.

Thinking on... there are so many other factors to be taken into account. If the direct flight takes about 20 hours, you can do the same schedule the very next day, but if the double flight takes over 24 hours then the following flights will not fit into a daily schedule. Aircraft only make money whilst they are flying, not whilst they are on the ramp or taxiing.
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Regardless of the route, it's highly unlikely that a stop is going to add 4 hours to the overall journey time. Bear in mind also that it won't be just a tech stop, you are also likely to be carrying revenue traffic to/from the intermediate point.

You're probably wishing by now that you hadn't asked. :O

By the way, did you read that link I gave you ?

As a customer who does at least one long haul a month, if not more I personally prefer a non stop as it allows me to arrive with some semblance of rest. Get on board get comfortable ask not to be bothered & go to sleep. Arrive with at least a few hours of shut eye & it helps the jet lag both ways... Added bonus is if/when I get to fly business then it is really a beauty. I hate the one stop flights as each segment does not allow more than a 4 hour rest given all the service shenanigans on both side of departure & arrival. Actually a total waste of a business class fare where you just cannot get a full 8 hours of shuteye. I always opt for the Long Haul over the hopping flights...That said longest I have take is about 16 hours.

Price points in Economy tend to be about +25% Different & in Business about +18% or so (When comparing hopping to nonstop).

Whist we will just have to agree to differ on the so called merits of ULH vs a stop, assuming your price analysis is correct, then this delta makes this company paid travel only?

On a single long flight, you will spend less time in the air than by breaking the flight into two legs.

Thus, less radiation.

I wish. Company pays for about 25% of the ULH (as that is the only travel I do on their behalf). I have to do a monthly commute paid from my pocket as the family stays a 14 hour plus flight away so it is a once a month trip. Company & personal is economy only & business is when I manage to grovel successfully. I leave the miles for the kids to use to come out to see me.

It is still worth paying the amount as it gives me an extra day with the family awake on each side.

Sounds crazy but yes there are paying people like me out there who lead such a commuting life in the quest of having the best of all worlds.

Not necessarily.

On a two-leg journey, a greater proportion of the overall flight time will be spent at lower altitude, in the climb and descent x 2, where the solar radiation effect is less. I think we need to see the sums.

I don't envy you

On a two leg journey, you will probably also be flying at a higher cost index, thus faster, as conserving fuel is less of an issue. Next to this ULH is more likely to go over the (north) pole, which has more ionic radiation.

I do. I just dream to have a situation like that.

Fine, I'll know not to bother next time ...

Link returned page not found. I would be interested in reading it.

I think the main problem with ULH is not the extra fuel itself, but the payload reduction to take that extra fuel. Also the extra crew (at full pay, weight and needing rest areas) is another big cost driver.

procede

I wouldn't worry too much about the payload side of the equation. Potential and actual customers such as SIA are past
masters at extracting the most watertight route performance guarantees from the manufacturers. They're in the sales contract.
No manufacturer wants the bad publicity and penalty payments that go with missing a guarantee. It has happened, but only rarely.

ULH would probably be cheaper: no single crew could do two 9 hour sectors, so would have to overnight a full crew prior (and after). Also, the ULH operation may only use 1 captain and 3 others, whereas if you did two sectors, you'd need two captains.

I'm guessing this is really dependent on the regulation of the crew. I think some crews are allowed up to 9 hours with a two person flight crew and crew on an overnight gets paid a lot less than the crew on an aircraft. Another issue is the legal rest times between flights.

Thanks for all the links, don't you just hate it when they do not label the X and Y axis of the graphs they use..?
That's a first-former's mistake...
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Not to be the pedant, but we need to be careful with the term direct versus non-stop. The former might actually involve a stop. Again, not to be picky but we just need to be aware of the difference.

Did we have these arguments when it first became possible to fly nonstop from say, London to Cape Town? At one time we had to stop at least once down the line. Nobody complains about that. Was a it so bad when it was suggested you would be spending 12 hrs in an aircraft without a break? Were the same fuel cost arguments used? What is the difference?

The effect on fuel burn, fuel carried and payload is disproportionally higher on ultra-long sectors, as discussed above and in the linked threads.

Interesting reading DRuk.
So all it needs is for the new aircraft to become fuel efficient enough to make it viable.
The A350ULR does this? I hope so.

How can this plane be economic?
 

See this linked article. https://www.flightglobal.com/news/articles/a350-900ulr-will-have-inactive-forward-freight-hold-449495/

Not only will pax capacity be reduced to 173 seats (80J / 93PE) on a plane that ordinarily holds 315 in the regular -900 version, but the forward cargo compartment will also be blocked off. So no cargo revenue and necessarily very high pax ticket prices. Other than for some very, very high premium-demand niche markets, it seems hard to imagine that it will have many takers. Looks just like the A340-500 all over again.