Will shorter legs reduce fuel burn?
 

I was interested to see a statement in last week's Flight International that by re-introducing intermediate refuelling stops on long sectors such as Europe to the Far East fuel consumption could be reduced by around 10%. We all know that the more fuel on board the higher the more burnt but surely adding an additional stop will in itself cost fuel. The extent will obviously vary according to how far the airport is off the great circle route and the amount of holding and taxiing required.

I'd be interested if any pilots or flight planners out there quantify this and give some examples. For example, what saving would LHR-BAH/MCT-SIN give compared to LHR-SIN non stop? Also what would be the best stopovers on the Europe - HKG route?

An additional factor would be increased station costs and of course greater block hours with associated crew costs (offset to some extent by a reduced need to carry relief crew) but they now of course account for a smaller proportion of costs than two years ago.

In general, best efficiency would be with sectors that had maximum payload (passengers + belly cargo), and longest range for that payload (only 1 climb and approach). For a long-range flight that had to be in 2 sectors, balancing them to approximately the same length should be most efficient.

I find that very difficult to believe! What about other factors too? Landing fees and as it's more than one sector you might need a crew change due duty hours so extra crew costs.

Fuel burn
 

I'm 5' 5" and my 330 still burns the same fuel. :O

fireflybob, the article is referring to fuel burn only, not other costs that may be involved. Discussed here http://www.pprune.org/forums/tech-lo...fficiency.html

Yeah, I KNEW some wiseguy was going to say something like this!

Okay, NoJoke, so now you've got to wear elevator shoes on one trip and compare the fuel burn to one with normal footwear. Let us know ... :8

If you think about it, the fact that Ronnie Corbett burns more fuel over a given distance at a given speed than John Cleese illustrates why shorter flown sectors need more fuel per sector mile than long ones.

Doesn't it?

That's probably because you have long legs and a short neck.

The corrrect answer would be: En route fuel stop only if necessary, and that's the case for fully loaded freighters.

Pax payload is less than freighter payload, thus a 14hr non stop flight is conceivably more cost efficient.

It wouldn't matter if the fuel burn were less with an en route stop, because the flight has to be cost based; not just "fuel-cost" based.

It would be difficult to even the cost savings when an airline would have to spend money for hotels, landing fees, crew salaries, ground handling, line maintenance, airplane wear and tear [cycles, brakes] . . . just to reduce fuel burn.

And who would fly on your airline from HKG to LHR via DXB if other airlines would fly nonstop?

Me.

I'd much rather have a stop in the middle and stretch my legs.

In fact I recently bought a LHR/DOH/HKG/DOH/LHR ticket for this reason.

As others have said, from the operational cost and not the pax comfort point of view I would say it was a no brainer. Tech problems tend to occur on take off and landing, wear and tear on the aircraft will double with additional pressurisation cycles, additional landings, (Brakes and gear) and additional take offs, (Engine wear). Additional landing fees, ground staff, (wages) and hotac if FLTs are critical will all add up. Now include a small tech fault that takes two or three hours to detect and clear, (assuming spares and engineering support available), and the crew go out of hours, you now have in the order of 400 hotel beds to find, meals to pay for etc. if you don't, (and are not likely to have), a spare crew ready to go.

As an academic exercise, "would an extra stop reduce fuel consumption", it is interesting in the theoretical sense but the possible exposure to considerable extra costs brought about by normal wear and tear and an unscheduled lay-over surely cancel any advantage?

Another important consideration is, it may be cheaper to upload fuel in the Middle East.

I'm sure more and more carriers will be using the ME as a "watering hole", hence why EK and the rest have such a huge advantage.

I see some reports (correct or not I've no idea) that fuel is currently about 60% of operating costs. That being the case, perhaps the bean counters are taking a look at the viability of an extra stop.

I'm with Parabellum, but for the simpler reason that a descent from FL350 or thereabouts, followed by manoeuvring for landing unless very lucky, followed by a climb back to that level, must surely take more fuel than carrying the extra needed to avoid doing that, if a choice is available.

Any F1 strategists out there?

I think the argument may be that it is cheaper to stop after, say, six and a half hours and refuel than burn the approximate '4% per ton' tanking penalty incurred if you plan a thirteen hour non-stop flight. I still think the extra wear and tear and cost of possible disruption, additional ground staff and flight crews, landing fees etc. etc. would outweigh the costs of non-stop fuel. Just my 2cents.

See what SIA do, they will have examined this scenario minutely!:)

Precisely, PB, and then there's the fact that a 1-sector duty becomes a 2-sector duty, although on a very long haul that's probably not an issue.

One possible factor in the other direction would be high uplift prices at the start point, and low prices at the tech stop point.

And if you have 3rd, 4th or best of all 5th freedom rights at the tech stop point you are creating many more revenue earning opportunities. But if you can fill the aircraft end-to-end anyway, that's not much of a gain.