Tankering Fuel
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Tankering Fuel
Hopefully someone can help me out here. I am wondering how much fuel an aircraft will typically "tanker" to a destination where the fuel is more expensive?
Let's say LGW-TFS on a 757, which would take about 13-14 tonnes trip fuel. Are we talking about taking 2 or 3 tonnes extra (on top of reserves) to save a bit of cost at the other end, or more like 10 tonnes extra to land @ MLW and not have to load very much in the tanks for the return trip at all?
Obviously the price difference must come into the equation somewhere as you must burn some of that extra (tankered) fuel simply to lug it around with you?
Any expanation would satisfy my curiosity! Thanks.
Let's say LGW-TFS on a 757, which would take about 13-14 tonnes trip fuel. Are we talking about taking 2 or 3 tonnes extra (on top of reserves) to save a bit of cost at the other end, or more like 10 tonnes extra to land @ MLW and not have to load very much in the tanks for the return trip at all?
Obviously the price difference must come into the equation somewhere as you must burn some of that extra (tankered) fuel simply to lug it around with you?
Any expanation would satisfy my curiosity! Thanks.
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Tankering is not just done for the purpose of saving money at destination, often the airline is contractually obliged to buy a certain amount of fuel per year and if they overestimate that amount then you find yourself carrying extra fuel just for the sake of buying it. I have tankered fuel to the Gulf before!
Generally in shorthaul we would try to estimate the amount of fuel required for the trip home and then load enough fuel so that we landed with that amount plus about 300kg (for APU burn). If you are leaving the aircraft downroute then you find yourself second guessing the fuel decision of the chaps who are taking over so we usually plan to land with a bit more to give them more flexibility.
In longhaul it is not usually possible to carry round trip fuel, so we plan to land at a tonne or two below max landing weight to allow for any enroute fuel savings.
Another consideration is the weather at your destination. If it is a bit chilly with high humidity or precipitation, then you can easily get icing on the wings as the extra fuel you have carried has cooled to subzero temperatures during the cruise. Deicing an aircraft will easily wipe out any cost savings made by tankering and so we would not tanker in such conditions.
Generally in shorthaul we would try to estimate the amount of fuel required for the trip home and then load enough fuel so that we landed with that amount plus about 300kg (for APU burn). If you are leaving the aircraft downroute then you find yourself second guessing the fuel decision of the chaps who are taking over so we usually plan to land with a bit more to give them more flexibility.
In longhaul it is not usually possible to carry round trip fuel, so we plan to land at a tonne or two below max landing weight to allow for any enroute fuel savings.
Another consideration is the weather at your destination. If it is a bit chilly with high humidity or precipitation, then you can easily get icing on the wings as the extra fuel you have carried has cooled to subzero temperatures during the cruise. Deicing an aircraft will easily wipe out any cost savings made by tankering and so we would not tanker in such conditions.
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A full / heavy 757 landing with 4 tonnes in reserve can only tanker about 3.5 tonnes, at which point it will land at max land weight. When there is more scope for tankering, the company i fly for, put a little more on and try to land at or about 90 tonnes.
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quota is another reason. if you operate a few flights into/out of a neighbouring country, you may be restricted to a quota as well.
or same country but diff airport, the more pop one will almost certainly have a quota.
another reason, although, rare, is the turn around time. if your handling agent is the bottom of the bid sort, he may be stretched for a refueller, so you may need to BYO.
on the 747-400, for every 1000kg of zfw incr (in this case fuel) we burn about 100 kgs over 7 hrs of flt.
or same country but diff airport, the more pop one will almost certainly have a quota.
another reason, although, rare, is the turn around time. if your handling agent is the bottom of the bid sort, he may be stretched for a refueller, so you may need to BYO.
on the 747-400, for every 1000kg of zfw incr (in this case fuel) we burn about 100 kgs over 7 hrs of flt.
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The usual reason is simple economics. If fuel is more costly at the destination it may be desirable to tanker to max weight ( landing or or Take off ) to save money on the overall round trip.
Simple formula is about 4% per hour of climb and cruise. On LGW TFS the flight time is around 4 hours of which 3.5 hours is climb and cruise. Thus 3.5 x 4% = 14%. So the fuel would need to cost 14% more at destination to start justifying the use of economy tankering. Obviously the higher the difference beyond 14% the greater cost saving.
There may be other factors to be taken into account beyond cost such as shortage of supplies at destination etc that may need to be taken into account.
Simple formula is about 4% per hour of climb and cruise. On LGW TFS the flight time is around 4 hours of which 3.5 hours is climb and cruise. Thus 3.5 x 4% = 14%. So the fuel would need to cost 14% more at destination to start justifying the use of economy tankering. Obviously the higher the difference beyond 14% the greater cost saving.
There may be other factors to be taken into account beyond cost such as shortage of supplies at destination etc that may need to be taken into account.
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With B738 when tnking is recommended we flight plan a maximum of 6 tons extra fuel for flights that are longer than 1hour due to wing icing problems and up to max LDW -300kgs
for less than 1 hour EET, provided the next sector is not in any way performance i.e TOW-LDW limited.
Long range a/c on short haul routes will often tanker enough fuel for both sectors, and when conditions permit will tanker on long haul routes as well, not so sure about the implications for wear and tear on the engines and airframe when the aircraft are routinely operating at at close to max wgt, I guess this muddies the waters further......
for less than 1 hour EET, provided the next sector is not in any way performance i.e TOW-LDW limited.
Long range a/c on short haul routes will often tanker enough fuel for both sectors, and when conditions permit will tanker on long haul routes as well, not so sure about the implications for wear and tear on the engines and airframe when the aircraft are routinely operating at at close to max wgt, I guess this muddies the waters further......
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If you know someone who has done the JAA ATPL exams ask to look at their CAP 697 Flight Planning Manual. It contains graphs to work out the economic utility of tanking fuel for a 737-400 (on the last two pages). This only takes into account cost difference compared to extra fuel burn.
Send Clowns
Flight Planning instructor,
BCFT
Send Clowns
Flight Planning instructor,
BCFT
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Thanks everyone that is now much clearer. Amazing how quickly I forgot the ATPLs Send Clown, dug out CAP697 from the loft and found that was a very easy way to work it out.
Do all aircraft have such a table?
Do all aircraft have such a table?
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there are many considerations that come into play when planning to tanker fuel. obviously $$$ savings is a major consideration, especially as fuel prices are climbing rapidly. we often tanker into stations where the fuel companies have increased prices dramatically as a shot across their bows. this has sometimes led to fuel prices dropping again.....so then we don't tanker. we also have to deal with extremes in wx conditions - don't want to tanker into/out of airports where adding wt to an aircraft becomes an issue - short rwys / high temps / snow&ice / heavy rain / tstms, flap-settings, heavy braking, etc. another factor is engine wear and tear.....we may save some money by tankering, but if having to use increased thrust to get out of dodge, any savings could be blown out of the tail pipe and/or increased maint costs. other factors may involve enroute wx - if you tanker to the gills and can only step climb, you may not be able to top enroute turbc. another factor is that if you tanker, you may not be able to get optimal flt levels - example, from minneapolis southbound, tankering may restrict you to fl330 initially - this will put you in direct conflict with east-west flow into ord, so you end up at fl290 for the first 45 mins of flt, whereas not tankering will let you climb straight to fl370, above the flow into/out of ord. so, many parts to the equation, and we need to make judicious decisions about this every day. it may may perfect sense to tanker one day, but the next day on the same flight, conditions may dictate otherwise. i could save my salary by tankering everyday, but have to temper this economic aspect with safety, which must come first.
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De-icing in the tropics.....
Yes, have seen it happen, usually by those whom have never noticed the frost on the underside of the wing before.
Startled guys on the 707's many years ago...but the storey is the same today as then...deicing not required.
Yet the stories continue......
Startled guys on the 707's many years ago...but the storey is the same today as then...deicing not required.
Yet the stories continue......
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deicing in the tropics
As an example, the A330, or 340 after a medium to long haul, landing in a humid enviro, will have cold soaked fuel in the order of -40 deg in the tip tanks. This may produce frosting on both the upper and lower surfaces.
411A, I am sure there is nothing many on this board would like to see more, than you demonstrating you superior ability in launching that puppy.
411A, I am sure there is nothing many on this board would like to see more, than you demonstrating you superior ability in launching that puppy.
