Originally Posted by JS

you gave people the option of paying $1,000 for a SFO-SYD trip with a stop in HNL or $1,200 for a non-stop flight, there will be people stopping in HNL, including me!

Originally Posted by CTPremEx

Agreed, but the 744 rule of thumb I stated as 24,000lb fuel per hour takes into account the very high consumption at takeoff power/climb, and the low burn at light weights in the last couple of hours plus descent. This works remarkably well for 6+ hours trips.

But using an actual flightplan, I see 314,875 lbs of fuel for a 13:20 flight - which is darned close to the rule of thumb figure of 324,000lbs for 13.5 hours.

Originally Posted by ozstamps

We are getting to the answer now it seems. Let's say we use around 320,000 lbs of gas as a back of envelope figure.

But we do not know United average gallon fuel cost (and there must be one surely?) and more important to this quiestion, what percentage of it is forward hedged, and what kind of typical figure.

I do know Qantas is very fully hedged at most attractive rates, and as their fuel surchages are same in $US as UA for USA runs, and the same figure even for 8 hour runs to Asia, must be getting their entire fuel cost near covered by these "surcharges".

I feel sure airlines do not just pay for gas like we do, based on what gas station they call into at random .... but presumably have some contract rate with one of the major oil companies, at least for USA hubs?

Originally Posted by NM

747-400ER
MGTW = 910,000 lb
MLW = 652,000 lb

Max fuel capacity prior to payload restriction = 258,000 lb
Max fuel capacity = 240,196 litres. Assuming a specific weight of 0.8, we get about 430,000 lb.

Fuel burn is about 29,000 lb per hour at MGTW, and about 20,000 at MLW. So assuming linear usage with weight decrease, we get an average fuel consumption of 24,500 lb/hour. So that gives us just about 10.5 hours flying time before we get payload restrictions. And at a cruise of M0.855, that's about 6000 miles in still air.

Now, we know that MEL-LAX is about 13.5 hours flying time (schedule is more like 14 hours, but flying time is usually 13-13.5 hours). So in that time, we will consume more like 330,000 lb of fuel, meaning a payload restriction of 72,000 lb or a landing weight of 580,000 lb.

So how many passengers does this mean we can carry. We know that QF have 354 seats on these aircraft. Assuming an allowance of 300 lb per passenger (for person, luggage, food, amenities etc), we get a pax load of about 106,000 lb.

EW is about 400,000 lb (depending on what is installed and new IFE takes it close to this) providing a payload of about 180,000 lb, of which we must also include fuel reserves (say 10% plus 1 hour or about 52,000 lb). This leaves us with 128,000 for pax and cargo, so we can just carry a full load of pax.

Now look at the return flight, taking more like 14.5 hours and we need a further 30,000 lb of fuel, leaving us 98,000 for our load of pax. So we should be able to carry about 326 of our 354 pax in this direction.

Now lets consider the 747-400 numbers:

747-400
MGTW = 875,000 lb
MLW = 652,000 lb

Max fuel capacity prior to payload restriction = 223,000 lb
Max fuel capacity = 216,840 litres or about 382,000 lb.

Fuel burn is the same as 747-400ER at about 29,000 lb per hour at MGTW, and about 20,000 at MLW. So we get the same 10.5 hours flying time before we get payload restrictions.

Our fuel consumption MEl-LAX after 13.5 hours is still about 330,000 lb, taking our landing weight down to 545,000 lb.

Empty weight is about the same at 400,000 lb at the ER, leaving us about 145,000 lb for payload. This must include fuel reserves (say 10% plus 1 hour or about 52,000 lb), leaving 93,000 lb for about 310 pax (out of 354 seats).

In the other direction, we lose closer to 100 pax seats.

Originally Posted by NM

Actually, there is one significantly higher cost - fuel. If flying SYD-LHR non-stop, you are over flying Asia, just not stopping to collect more fuel. So the extra fuel you would have taken on in SIN or HKG must be tankered (freighted) in the fuel tanks all the way from SYD.

Fuel burn is very much related to aircraft weight. Improvements in aircraft and engine performance can reduce burn by a few percent (still significant costs), but the more weight you have to keep in the air, the more fuel you burn. Lets assume an aircraft the size of a 772LR has a MTOW of 766,000 lb, we can assume an initial fuel burn rate in the order of 24,000lb/hour. So in the eight hour or so it takes to get to the point in Asia where we currently refuel, we would have burned about 168,000lb of fuel at an average of about 21,000lb/hour since the aircraft weight is continually decreasing as we burn the fuel.

The second part of the journey, say the 12 hours equiv of SIN-LHR will have a lower average fuel burn, of say 17,000lb/hour (down to as low as 13,000lb for the last hour), or 204,000lb.

If we did not have to carry that 204,000lb of fuel from SYD to somewhere over Asia, we could have carried more payload (potentially 204,000lb worth) or used less fuel to get to that point in the flight. Tankering 204,000lb of fuel is going to require an extra fuel burn of something like 6500lb/hour. So for 8 hours, that is 52,000lb of fuel.

So the fuel cost for a non-stop SYD-LHR is going to be higher than for SYD-SIN-LHR, and the potential payload is also significantly reduced just due to the weight of the fuel that must be carried to complete the non-stop flight.

Add to that the increased weight of things like on-board catering requirements for the longer flight (twice the amount of water, for example), and it all costs money (eg fuel) to freight from A to B. By stopping enroute, the catering can be replenished and waste tanks emptied.

Remember that back in the late 60's many airlines placed orders for Concorde. What was one of the significant factors that caused them all (except BA and AF) to cancel their orders? The sky-rocketing price of fuel at the time! Look for some similarities between the economic events of that time and today. The touted efficiencies of today's ultra long range airliners were calculated when jet fuel was considerably less expensive than it is today. If these high fuel prices continue, the cost of tankering half your fuel over long distances becomes is significant factor in the viability of operating ultra long range services.

I am not suggesting the current fuel cost hike is going to be the demise of modern ultra long range aircraft, but I do believe the airlines are starting to rethink the costs associated with operating these services now that one of the contributing variables in the equation has significantly altered.

Originally Posted by NM

What makes a good freighter and what makes a good passenger airliner are not necessarily the same things.

When selecting a freighter, the operate looks for an aircraft with a very large spread between MLW (Max Landing Weight) and EW (Empty Weight). This is the amount of cargo that can be carried. Freight operators are looking for a large spread as a proportion of the EW, or how much dead weight you have to carry per pound of cargo. For large freight volumes, the MD11, DC10, 747F and even DC8 is very attractive in this regard.

As it turns out, for most common cargo loads, the MD11/DC10 run out of lift and cargo capacity (volume) at about the same time. The 747's tend to run out of lift before they run out of volume.

So a 777 or A330 or even 747 may be able to carry the cargo further, but the reality is that cargo does not mind if it takes 18 hours to cross the Pacific Ocean or 14 hours, and cargo does not mind what route it takes - passengers do and they need to be fed and entertained along the way.

So for freight operations, carrying a larger amount of freight and less fuel, and then refuelling enroute, can make for more efficient operations than long distance point to point operations.

The other number that is of interest to freight operators is the ratio of fuel burn per hour / (MGTW-MLW). This is basically the range, and as long as this number is 5100 miles, it works well for freight ops. Remember that freights tend to operate between freight hubs, so the longer runs tend to be such as ANC-HKG or HNL-SYD. Look at the operations in/out of ANC and HNL each night and you will see how they operate as freight hubs.

On the other hand, passengers operations require longer range non-stop services. Passengers don't want to stop in ANC or HNL for fuel between USA and Asia.

So if we consider the operational numbers for a passenger MD11 flying, say LAX-HKG, we find EW=295,000 lb, MLW=440,000 lb, and MGTW=630,000 lb. Any flight that consumes more than 190,000 lb of fuel is converting payload into fuel at a rate of about 3lb/mile. LAX-HKG is about 15 hours much of the year (due to winds) and at about 16,000lb/hr fuel burn plus ground and climb usage (say another 15,000lb), we will consume about 255,000lb of fuel.

Now subtract this 255,000lb fuel from MGTW and you get 375,000lb max landing weight, of which about 10,000lb will be fuel reserves. This leaves us a total of 70,000lb of usable payload for passengers, cabin amenities, luggage, catering etc. This means we have a severe passenger restriction for this flight.

If you perform this same long-haul non-stop passenger service with a 747-400 (as CX does), you will consume about 330,000lb of fuel, and need about 12,000 reserves, so 875,000lb (MGTW) less 342,000lb fuel give us 533,000lb MLW against a EW of 398,000lb, or 135,000lb uplift capacity to work with instead of 70,000 lb for the MD11, which is a whole lot more realistic and viable.

These numbers are much more attractive for the B777 and newer A340's for non-stop long haul passenger operations. Hence the demise of the MD11 as a passenger airliner, while it continues to be an admirable freighter.

Now suppose I want to fly freight LAX-HGK non-stop. MLW of my MD11F = 480,000lb and EW = 265,000lb, while MGTW = 630,000lb. We are still going to consume 255,000lb of fuel and require 10,000lb fuel reserves, so I have 365,000lb MLW. Take away the EW and this gives me 100,000lb of cargo payload.

However, what happens if I choose to give my cargo a break in ANC on the way? This will add about 200 miles to the flight, out of more than 7000 miles total, and of course we burn more fuel for the extra take-off and landing, as well as about 2 hours additional time.

LAX-ANC is about 2350 miles and will take about 5 hours, burning 90,000lb of fuel. Since this 90,000lb of fuel is way less than the spread of MLW and MGTW, this sector is limited only by max landing weight. That means my payload can be the entire spread between EW and MLW less the required fuel reserves, so I can carry about 206,000 lb of cargo.

ANC-HKG is 5080 miles and against prevailing winds is likely to take about 11 hours, consuming about 175,000lb of fuel, plus 15,000lb for ground and climb out, plus 10,000 reserves, making fuel requirements about 200,000lb. This makes the payload 430,000-265,000=165,000lb (MGTW-InitialFuel-EW). So my two-hour fuel stop in ANC has increased my payload by 65%, while fuel costs rise about 10% and crew costs up slightly.

But passengers would not appreciate the 2-hour fuel stop in ANC! Freight does not complain, and does not need toilet breaks etc.

Freight operators like Fed-ex that get very good utilization out of their aircraft ensure that the operating cost efficiencies of their new MD11's (for freight ops as described above) outweigh the capital costs. For freight operators that have much lower aircraft utilisations, the capital costs are a more significant function and they will tend to look for less expensive purchase costs and older DC10, B747, A300 and even DC8 aircraft fit their needs better.

So MD11's make good freights so long as you don't try to fly them further than the spread between MGTW-MLW. 777 makes a great pax airline because passengers don't want to take an extra 2 hours to fly long-haul ops.

Originally Posted by NM

Sorry for the long winded reply, but it I thought it might help to understand the discussion.

From my calculations, the current fuel surcharge are certainly making a significant contribution to the overall fuel cost for most flight operations, but is certainly not covering the entire fuel cost.

Originally Posted by gnaget

UA is supposedly unhedged due to the bankruptcy so they are stuck with spot prices. Obviously they can get some sort of discount but it's all relative.