Fuel Conservation

[richard III]

Hi everyone:
I believe the downturn has produced strain in our industry in every corner of the world, and obviously fuel is one of our main concerns as pilots. Besides the obvious, I would like to initiate a serious discusion about fuel conservation. For instance, could we quantify the savings for take offs with flaps 5 instead of 15 in boeing aircraft?, does somebody have a real formula to calculate cost index? safety concerns and advantages of setting climb power at 500 ft. versus 1000, I read somewhere that lufthansa got a very good new program for this...etcjust keep ideas coming and see what comes out of it.
It would be an interesting thread for the ones that want to find ways to alleviate somehow the financial stress our airlines are going through and maybe help ourselves at the same time.

[rubik101]

Again?

This subject has been discussed at great length over the past couple of years. Try a search and your questions will be answered in great detail a great number of times by a great number of contributors.

[PappyJ]

I believe the downturn has produced strain in our industry in every corner of the world, and obviously fuel is one of our main concerns as pilots.

Regardless of the state of the economy, or the prevailing cost of fuel, reasonable effort should always be made to conserve it. I'm not be any means a tree hugg'in whale defender, but face it, fuel is NOT a renewable energy source. If we can use our brains to save some (Without compromising safety) - regardless of it's current cost - then we owe it to everyone to do that.

Besides the obvious, I would like to initiate a serious discussion about fuel conservation.

And so you did!

For instance, could we quantify the savings for take offs with flaps 5 instead of 15 in Boeing aircraft?,

I can't speak for the current Boeing models, but the difference in the Airbus is about 80 kilos between Flaps 1 and Flaps 2 for take-off, with default ACC ALT, etc.

does somebody have a real formula to calculate cost index?

Yes, the manufacturers produce this information. However, CI encompasses more than just fuel. It's a strategic number that include the "Total Cost" of operations.

safety concerns ....of setting climb power at 500 ft. versus 1000

All engines running; there is no compromise to safety. Remember, if you're doing this; performance has been calculated, and is acceptable, for that procedure.

advantages of setting climb power at 500 ft. versus 1000

Here's where they may be confused. I played with this a little during an extended turn on the ground. Basically, plugged a variety of different numbers into the FMS and noted the predicted Arrival Fuel at the destination.

What I discovered - for the Airbus:

The default Thrust Reduction and Acceleration altitudes are 1500 AGL. When I changed them to 1000 AGL, it indicated no change in the arrival fuel.

But, when I set both to 5000 feet AGL, I found a 200 kg INCREASE in the predicted Arrival Fuel.

When I did the same calculation with TOGA thrust to 5000 feet, I found a 300 kg INCREASE in the predicted Arrival Fuel.

Of course, there would have been the additional wear & tear on the engines by using the increased thrust.

And before anyone gets it in their mind to beat me up over it, obviously, I followed my company's SOP for the actual flight, but it was interesting to note the differences.


The point. Cost saving is a compromise between reducing the costs on the hardware (Engines) and the cost of the consumables (Fuel).

I read somewhere that Lufthansa got a very good new program for this

Germans! I'd expect that.

[richard III]

Hi pappy:
Thaks for the post, I just initiated the case since I have the feeling that I don't see crews doing an effort to conserve fuel an therefore the same on the enviromental print. I downloaded some info from boeing for instance,
Difference on a take off with flaps 10 versus flaps 20 on a 744 varies from 200 to 300 kgs. per take off, and in 777 is 150 to 200kgs. for a take off with a larger flap setting. Imagine the yearly savings in a year.
Germans ,beside a software they have for citylink which has produced huge savings, they reduce speed on long haul flights if they are ahead of schedule to save fuel.
There's another airline that claims that it saves 50kg. per take off by just setting climb thrust at 500ft. agl instead of 1000ft. Is there a Safety compromise behind this?
I see crews doing hi speed descents almost like SOP's burning extra fuel unnesesarily etc.
The idea is that I wouldn't want to get shot down if I initiate a discussion that may not be welcome by management, just guessing though. Therefore triyng to get as much info as possible on the subject.
Best regards

[PappyJ]

Imagine the yearly savings in a year.

Yes, some airlines have already recognized the benefit.

Is there a Safety compromise behind this?

Provided that the performance, climb gradient and other factors are considered, I think most folks would agree that there is no compromise to safety.

I see crews doing hi speed descents almost like SOP's burning extra fuel unnecessarily etc

I see it all the time. Personally, I like to stay high, then plan the descent to 1000 AGL with the thrust at idle (whenever possible). I'm also not a fan of high speed (Below 10000 feet) for another reason - Birds! A bird strike at 250 kts is one thing, but at 330 knots, well???

The idea is that I wouldn't want to get shot down if I initiate a discussion that may not be welcome by management, just guessing though. Therefore trying to get as much info as possible on the subject.

I'd be surprised if your management group would be opposed to saving money! Provided of course that it didn't cost them any to do that.

With that in mind, people can be weird. I've been in more than my fair share of piss'in contests with managers who didn't want to accept that one of their "Subordinates" came up with a more efficient way of doing something then they did. I guess its a face-saving thing. Funny though, they're the same folks want everyone to have warm and fuzzy CRM skills.

[richard III]

hey pappy:
on the last statement I'll be happy to leave all the info on their desk, I'm no gong chaser, just happy if the airline does good and I keep my job, good point on the face saving....sounds familiar.

[Slasher]

The ultamate A320 fuel saving method.

Tow out to TO runway threshold - GPU + GTSU for starting both eng - packs off TO - TOGA to 3000' - cleanup - green dot climb - Crz and Desc CI '0' - green dot desc from 10000' - Conf 1 at GS int 3000' - 2 at 2000' - 3 at 1000' - gear down at 500' - idle rev only on ldg - shut down engines on runway - tow in to bay.
No APU, no clb/desc level-offs, only 1 pack on, no galley power, no TAI.

[captjns]

Back in the day even when the price of fuel was not an issue, we would use max thrust for takeoff, max climb thrust to cruise, and monitor time of climb to next flight level. This helped to keep more fuel in the tanks to make destination with extra. We would stay high as long as possible, and basically glide from altitude to about 3 to four hundred feet AGL. High speed descents do not consume any extra fuel, provided you are at flight Idle from TOD to the same given point in space we are fully configured.
Larger aircraft may require greater flap setting for takeoff provided climb or obstacles are not an issue. This keeps the ground speed down during high gross weight high temperature days, thus keeping in line with the tire speed limits.
Bean counters or even actuaries that have true knowledge of commercial aviation need to run a cost analysis of fuel consumption versus to the cost of wear and tear.
Less than all engine taxi will save fuel, especially at the light weights after landing, and when a gate is not available will save fuel. This is of course the engine has had adequate time to cool down after landing. We do it all the time. However, the same may not apply during taxi out at high gross weights because of the additional break away thrust required to get the jet to move. Assembly line aircraft are not equipped with the sophisticated forensic type of instrumentation see true fuel flows or fuel consumed to the degree of accuracy to make such detailed fuel consumption analyses. More data, on an airport by airport basis, is needed to determine the fuel savings too. To name a few… fuel density, tire pressure, taxiway slope, aircraft gross weight, ambient pressure and temperature, cross wind components, will all may be minor by themselves, but combinations of all may have relevance.
Also, the manufacturer will indicate gross weight recommendations to be observed when performing less than all engine taxi in order to avoid fan blade flutter.
In an ideal operation, a tug to and from the terminal to the runway would save tons of fuel and money. Imagine the number tugs and labor, not to mention ATC communications and coordination required accomplishing this feat in say JFK or ORD, or even LHR would be high too. Would airport authorities want to design and construct special "TUG ROUTES" to help accomplish this means of fuel conservation and the added bonus of helping the local ecology?

[PappyJ]

So, you would like to discuss fuel economy...? Scroll back to 1973, it started then, and we still try. Maybe you were born after that year... You want to save fuel to a maximum, so let us do it this way - Airplane with 300 seats, no schedules, departure when the 300 seats are filled... full airplanes as a rule, no empty seats. Cargo airplanes only cleared to go when loaded to MZFW...

It wasn't long ago (1989sih) that I saw an Aeroflot doing the same thing in Anchorage. When asked why they were parked so long, the local rep quite frankly responded, "...not full..."

Otherwise, you're right about "..."personally, I like to...", One reason that comes to mind for why this happens, may the absence of more defined SOP guidance. Obviously, there's only so much you can write in an SOP before it becomes too restrictive. I suppose that's one of the reasons why they all contain a clause to the effect of, "...good judgment and airmanship shall prevail..."

Overall, you're right about this; in that we seem to be constantly trying to "Reinvent the wheel". As you indicated, we're been chasing this fuel saving ghost for decades.

Two problems that tend to come back to haunt us are;

One, the equipment changes, thus we are forced to redefine "Fuel Savings".

And two - I think the greater problem - the fuel price changes. When the price goes through the barn roof, it's only then that we climb back on the fuel saving horse again. Basically, I guess everyone becomes complacent until we're bitten once again.

Fortunately, I've got more years in this circus show, than I have left in it. Maybe they'll sort it out before my days of over. I doubt it, so save a rockin' chair for me and we'll share the laughs.

In an ideal operation, a tug to and from the terminal to the runway would save tons of fuel and money. Imagine the number tugs and labor, not to mention ATC communications and coordination required accomplishing this feat in say JFK or ORD, or even LHR would be high too. Would airport authorities want to design and construct special "TUG ROUTES" to help accomplish this means of fuel conservation and the added bonus of helping the local ecology?

Like I said, it's all about compromise.

[Max Angle]

High speed descents do not consume any extra fuel, provided you are at flight Idle from TOD to the same given point in space

I would beg to differ. If you plan a high speed descent your TOD point obviously moves closer to your destination resulting in longer spent with the engines cruise fuel flows. A slow speed descent can mean up to 5 minutes more time with engines at idle resulting in a fuel saving which is why very low cost indexes produce slow descent speeds.

[B-HKD]

The software LH cityline integrated into the EFB, is called Pacelab CI OPS.

Simply said, it allows the crews to dynamically update the initial planned cruise procedure as flight conditions change, and from the screenshots I've seen it has a clear and simple interface.

Zoni

[OPEN DES]

The ultamate A320 fuel saving method.

Tow out to TO runway threshold - GPU + GTSU for starting both eng - packs off TO - TOGA to 3000' - cleanup - green dot climb - Crz and Desc CI '0' - green dot desc from 10000' - Conf 1 at GS int 3000' - 2 at 2000' - 3 at 1000' - gear down at 500' - idle rev only on ldg - shut down engines on runway - tow in to bay.
No APU, no clb/desc level-offs, only 1 pack on, no galley power, no TAI.

I beg to differ.
The ultimate fuel saving scenario: (excluding things like GPU, tow out/in etc)
-TOGA thrust for 5/10 min with packs off as long as practical
-Minimum fuel would be achieved by an as low as possible accel. (400ft AAL iaw PANS-OPS). With T/O at min flap setting (1+F).
-Minimum trip fuel would be achieved at climbing at max r.o.c. speed (CI=0)
-Min. trip fuel during cruise flying CI=0=max. r.o.c. speed=V max range at OPT FL or above when anticipating step clb.
-Same theoretically for descent but FMGS defaults to 250/270 kt minimum at CI=0 depending on company options. CI=0 would theoretically give you green dot speed. So select green dot speed to get best L/D ratio: best gradient for descent (longest possible descent time in idle thrust=earliest descent possible at idle thrust=shortened cruise time)
-decelerated approach; spool-up/stable at 500ft/1000ft

[Sir Richard]

Continuous Descent Approach, Minimum Landing Flap and Idle Reverse all save fuel (and decibels)...when conditions are appropriate.

[Anp]

Try this sometime:
On DES page manually insert different descent speeds and notice the FOB at destination change. Too high a speed may result in lower FOB at destination. Also notice the arrival time change. As long as the FOB at des remains unchanged, an increased des speed gives a later descent point, an earlier ETA and therefore savings for the company.

[Canuckbirdstrike]

ANP Jumpin Jack Flash is correct. The FMC data set, algorithms and rounding yield very imprecise answers. In comparison to an industry standard flight planning system with accurate CI information the FMC is like a basic calculator vs. a top of the line quad core PC.

We must remember that the key in fuel conservation is the repetitive savings over time. Save 30 kg a flight, for 600 flights a day and well you get it.

The FMC is another flight deck tool with lots of limitations. Its abaility to out perform a flight planning system is a non-starter and using it for precise fuel savings analysis is next to useless. Optimum altitudes, climb/descent/cruise fuel savings values are inaccurate for all the reasons cited.

[FullWings]

How about a visual circuit instead of a 10-mile ILS?

[Ocampo]

How about a visual circuit instead of a 10-mile ILS?

I'm up for that! I'll take the visual approach whenever I have VMC; IMO that's a nice way to save fuel