MPG of a Boeing 737-800

idunnoshur

Hi everyone, today my cousin rang me asking how much fuel a Ryanair plane uses on a typical journey say from Cork to Heathrow, he has to do a college project on it. I told him that I'd look into it for him but so far all that I've found is that they typically do 82 MPG over a long run once they've taken off. Roughly how much fuel is burned during take-off and landing? He said that the average number of passengers they carry is 189, I'm not sure if that makes much difference either!

Thanks
ids

John_Mc

idunnoshur wrote: »

Hi everyone, today my cousin rang me asking how much fuel a Ryanair plane uses on a typical journey say from Cork to Heathrow, he has to do a college project on it. I told him that I'd look into it for him but so far all that I've found is that they typically do 82 MPG over a long run once they've taken off. Roughly how much fuel is burned during take-off and landing? He said that the average number of passengers they carry is 189, I'm not sure if that makes much difference either!

Thanks
ids

189 is the max amount of passengers so it is definitely not the average. I'd say they'd be doing well with a load factor of 80% of that.

Can't help you with the other figures - sorry.

IngazZagni

Tomorrow's flight from Cork to Gatwick with Ryanair will burn off approximately 3,000kg of fuel, that's 3.3 tons. That's with no wind, so if there's a headwind it will burn more and if there is a tailwind, it will burn less. In the climb it will burn approx 1400kg, in the cruise it will burn approx 1300kg and if they have a nice idle powered decent path they will burn only about 300kg.

With 189 pax, the aircraft will burn more fuel than with 100pax but with 189pax, the fuel burn per passenger will be less. Also fuel on aircraft is measured in weight, not quantity as fuel can change density with different temperatures giving different readings, but the weight will stay the same. Hope that helps a little.

idunnoshur

John_Mc wrote: »

189 is the max amount of passengers so it is definitely not the average. I'd say they'd be doing well with a load factor of 80% of that.

Can't help you with the other figures - sorry.

So what would the average figure be; 80%?

IngazZagni wrote: »

Tomorrow's flight from Cork to Gatwick with Ryanair will burn off approximately 3,000kg of fuel, that's 3.3 tons. That's with no wind, so if there's a headwind it will burn more and if there is a tailwind, it will burn less. In the climb it will burn approx 1400kg, in the cruise it will burn approx 1300kg and if they have a nice idle powered decent path they will burn only about 300kg.

With 189 pax, the aircraft will burn more fuel than with 100pax but with 189pax, the fuel burn per passenger will be less. Also fuel on aircraft is measured in weight, not quantity as fuel can change density with different temperatures giving different readings, but the weight will stay the same. Hope that helps a little.

I presume it's kerosene that they burn is it not? Also how far will it travel during the climb, is this a constant figure or does it vary on the length of the journey?

I wasn't aware that they're most efficient when full. I find that bit about the fuel interesting but I doubt the cousin will be able to grasp it.

Thanks!

IngazZagni

idunnoshur wrote: »

So what would the average figure be; 80%?

80% is about the average load factor yeah.

idunnoshur wrote:

I presume it's kerosene that they burn is it not? Also how far will it travel during the climb, is this a constant figure or does it vary on the length of the journey?

I wasn't aware that they're most efficient when full. I find that bit about the fuel interesting but I doubt the cousin will be able to grasp it.

Thanks!

Yeah, jet aircraft mainly use Jet A1 which is a kerosene type fuel.

They will travel different distances in the climb depending on a number of factors. For a short hop from say Dublin to Manchester, you may only climb to 23,000 feet or so and that might only take 40 miles or for longer flights up to 37,000 it could be 150 miles. On top of that aircraft may be restricted by ATC and have to level off at lower altitudes due to traffic in the areas. So you could fly a considerable distance before reaching your cruise altitude. This is very common in London.

idunnoshur

IngazZagni wrote: »

They will travel different distances in the climb depending on a number of factors. For a short hop from say Dublin to Manchester, you may only climb to 23,000 feet or so and that might only take 40 miles or for longer flights up to 37,000 it could be 150 miles. On top of that aircraft may be restricted by ATC and have to level off at lower altitudes due to traffic in the areas. So you could fly a considerable distance before reaching your cruise altitude. This is very common in London.

Thanks very much! You seem very knowledgable on flights, are you in trade?

IngazZagni

idunnoshur wrote: »

Thanks very much! You seem very knowledgable on flights, are you in trade?

Ha, yeah I work in the pointy end of the plane.

xflyer

It is more efficient with more passengers but essentially that's an economic factor. More weight burns more fuel. But with 189 paying passengers on board the cost is spread over more people. Thus greater efficiency.

You can work out MPG if you know the specific gravity (SG) of the fuel. But it varies with temperature and indeed the source of the fuel. So you won't get a precise figure very easily unless you are there when the aircraft is refuelled. As the temperature drops so does the volume although the weight remains the same as the density increases. Which means that at altitude the volume is less. So you can see why weight rather than volume is used. In effect MPG varies throughout the flight.

So to even get an approximate MPG you need to know the SG of the fuel. But an approximation can be worked out. Generally SG of Jet A1 is in and around .80. So your cousin can simply multiply the total weight of the fuel used by the SG. Using IngazZagni's figures the total is 3000kg

3000 / .8 = 3750 litres. .84 = 3571, .79 = 3797. A spread there of 150 litres. * corrected

If you know the distance between Cork and Gatwick you can work out the MPG. Your cousin could explain that the actual MPG will vary within a certain range.

But that's only averaged for the entire flight. If you want to know the MPG in cruise you need the SG adjusted for temperature at altitude. Same for the climb and descent. Of course the temperature will be changing during climb/descent, thus changing the SG and the MPG. Naturally of course you will also need to know the distance travelled for each part of the flight. It's all a bit head wrecking.:(

Amazing what I remember of the ATPL exams. Assuming I have remembered properly. Hope that helps or have I completely confused the situation.

Su Campu

xflyer wrote: »

It is more efficient with more passengers but essentially that's an economic factor. More weight burns more fuel. But with 189 paying passengers on board the cost is spread over more people. Thus greater efficiency.

You can work out MPG if you know the specific gravity (SG) of the fuel. But it varies with temperature and indeed the source of the fuel. So you won't get a precise figure very easily unless you are there when the aircraft is refuelled. As the temperature drops so does the quantity although the weight remains the same as the density increases. Which means that at altitude the quantity is less. So you can see why weight rather than quantity is used. In effect MPG varies throughout the flight.

So to even get an approximate MPG you need to know the SG of the fuel. But an approximation can be worked out. Generally SG of Jet A1 is in and around .80. So your cousin can simply multiply the total weight of the fuel used by the SG. Using IngazZagni's figures the total is 3000kg

3000 X .8 = 2400 litres. .84 = 2520, .79 = 2370. A spread there of 150 litres.

If you know the distance between Cork and Gatwick you can work out the MPG. Your cousin could explain that the actual MPG will vary within a certain range.

But that's only averaged for the entire flight. If you want to know the MPG in cruise you need the SG adjusted for temperature at altitude. Same for the climb and descent. Of course the temperature will be changing during climb/descent, thus changing the SG and the MPG. Naturally of course you will also need to know the distance travelled for each part of the flight. It's all a bit head wrecking.:(

Amazing what I remember of the ATPL exams. Assuming I have remembered properly. Hope that helps or have I completely confused the situation.

Good explanation, though I think you mean volume rather than quantity.

xflyer

Oops, points deducted, duly corrected.;)

mickdw

If SG of the fuel is 0.8, doesnt that mean that your calculation should have been

3000kg/08 = 3750L fuel

seeing as 3000kg of water equals 3000L and SG of 0.8 means the fuel is less dense than water so more than 3000L fuel for 3000kg not less like you stated above

Bessarion

My head hurts.............

tippilot

mickdw wrote: »

If SG of the fuel is 0.8, doesnt that mean that your calculation should have been

3000kg/08 = 3750L fuel

seeing as 3000kg of water equals 3000L and SG of 0.8 means the fuel is less dense than water so more than 3000L fuel for 3000kg not less like stated above

More points deducted xflyer the man is right! Back to the books!

funhouse18

I presume you all mean mass rather than weight?

Weight = mass x gravity

Gravity changes with maneuvers. I'm sure your fuel gauges don't go up or down in a steep turn?

IngazZagni

funhouse18 wrote: »

I presume you all mean mass rather than weight?

Weight = mass x gravity

Gravity changes with maneuvers. I'm sure your fuel gauges don't go up or down in a steep turn?

Haha I was trying to keep it simple but then this turned into an ATPL forum lol. I didn't think the OP's cousin was interested in the SG of fuel and converting kg's to litres and mass vs weight etc. But reading it does make me glad the ATPL's are behind me!

idunnoshur

Thanks for all of the replies lads. My Leaving Cert chemistry and physics is just enough for me to follow this. I'll show this page to the cousin, I'm sure there's more than enough here for him to work it out, he's probably better than me at physics and chemistry at this stage!

I also didn't realise that pilots had to know all of that about the fuel, i would've thought that the computer did everything for them.

IngazZagni wrote: »

Tomorrow's flight from Cork to Gatwick with Ryanair will burn off approximately 3,000kg of fuel, that's 3.3 tons.

Just noticed your error there, 3000 kg of fuel would be 3 tons :P

xflyer

Doh, I multiplied instead of divided and then failed to carry out the gross error check. It was late and I was tired, (excuses excuses).

That's why computers are mostly used!

duboce

Reading this is like you guys all from the 'Big Bang Theory' series

I'd be like penny and guess the aircraft MPG works out at

APPROX VALUES

First estimating the distance to be 300 miles

Works out at 10Kg of fuel per mile or 0.465 MPG for the aircraft

or to put in layman terms = A car with 4 people doing 22 MPG

But you have to be amazed with the aircraft travelling at over 500 MPH this is excellent fuel consumption

IngazZagni

idunnoshur wrote: »

Just noticed your error there, 3000 kg of fuel would be 3 tons :P

Ha yes it would. But I lived in the States for a couple years and I think they have a slightly different measurement for tons than we do. I remember getting confused over that when I moved back here. Short tons and long tons I think it is. But the metric ton is the easiest to use because it's a rounded figure and yeah the one used here.

mickdw

Assuming 360 miles between airports, and a 3000kg of fuel used on a 737

3000kg is approx 826 gallons (taking sg of 0.8).
so thats 0.435 mpg that the aircraft does.

MPG for both car and plane:

Typical diesel car 45mpg carrying 4 people (80% full)
Plane 0.435 mpg carrying 150 people (80%)

Considering the plane uses 103.44 times more fuel than the car but with people numbers 37.5 times greater, we can say that the plane uses 2.76 more fuel per person than the car per person.

Or look at it like this:

Gallon per miles per person makes a bit more sense than mpg when talking about per person figures so:

Car = 0.02222 g/mile(4 people)
= 0.005556 gallon/mile per person

Plane = 2.29 g/mile (150 people)
=0.01526 g/mile per person

i.e. plane uses 2.75 times more fuel per person than car per person.

Compare the plane to a car with only 1 person though and the car driver ends up using 1.45 times more fuel than plane pasenger assuming plane is 80% full.

donvito99

idunnoshur wrote: »

Ryanair plane uses on a typical journey say from Cork to Heathrow

:pac::pac::pac:

kub

donvito99 wrote: »

:pac::pac::pac:

I know they don't but, I think during the AL strikes when they hired in FR machines then FR did indeed do this route

xflyer

Reading this is like you guys all from the 'Big Bang Theory' series

You see pilots ARE intelligent...............well some. Those who know the difference between division and multiplacation.

The one thing I've learned from this thread: Google is your friend. Don't guess Google it:p

Stinicker

I read somewhere that an A380 at a full load of 800+ all economy will be the most efficent means of transport over a long distance. Of course no airline as of yet has launched with the all economy option but Air Austral will when they get theirs. It seems a load of fuel is used in the climb, does flying at such a high altitude make sense for short hops or is the air really that thin up there which then saves on the fuel burn.

Run_to_da_hills

Stinicker wrote: »

I read somewhere that an A380 at a full load of 800+ all economy will be the most efficent means of transport over a long distance. Of course no airline as of yet has launched with the all economy option but Air Austral will when they get theirs. It seems a load of fuel is used in the climb, does flying at such a high altitude make sense for short hops or is the air really that thin up there which then saves on the fuel burn.

Have the Japanese ordered any of these? JAL was probably the first airline to kit out the 747 in all economy formation for short hop unternal commuter routes.

savagecabbages

Pondering on what Stinicker said, I think I recall reading/hearing that Concorde was one of the most fuel efficient passenger aircraft ever made once at cruising altitude + speed, but burned LOADS getting up there. Anyone more learned than me care to confirm/rubbish my thoughts?

Stovepipe

Also, don't forget that the 737 has two engines, so divide the consumption figure in two. Also, airlines calculate fuel costs in seat-mile(s/m) or revenue per passenegr per kilometre (rpk) so miles to the gallon, because of all the highly variable factors already posted here, is not really relevant to aircraft operations.
regards
Stovepipe

Run_to_da_hills

More to the point, how much would the average Boeing 738 with 80% pax capacity cost on fuel for a trip from Dublin to Stanstead.

Gracelessly Tom

Run_to_da_hills wrote: »

Have the Japanese ordered any of these? JAL was probably the first airline to kit out the 747 in all economy formation for short hop unternal commuter routes.

So far Skymark are the only Japanese airline to order the 380.

Tenger

Gracelessly Tom wrote: »

So far Skymark are the only Japanese airline to order the 380.

But JAL and ANA have asked Boeing for a 300 seater version of the B787 (Boeing markets it as a 200-250 seater)

It was shelved but there was a B787-300 design that was intended solely for the Japanese domestic market.

Transaero have ordered the A380, we might see a large capacity on those units.

Gracelessly Tom

Tenger wrote: »

Transaero have ordered the A380, we might see a large capacity on those units.

Three cabin config with a capacity of 700.

idunnoshur

Stovepipe wrote: »

Also, don't forget that the 737 has two engines, so divide the consumption figure in two. Also, airlines calculate fuel costs in seat-mile(s/m) or revenue per passenegr per kilometre (rpk) so miles to the gallon, because of all the highly variable factors already posted here, is not really relevant to aircraft operations.
regards
Stovepipe

Forgive me if I'm way off the ball here but aren't most airplanes engines in the wings? If that's the case wouldn't they all have to have two to balance the plane?

I'm finding all of this talk of planes very interesting, pilots must be reasonably good at chemistry, I had thought that they just had to know how to drive the plane. Is there much to know about the weather for pilot exams?

Gracelessly Tom

idunnoshur wrote: »

Forgive me if I'm way off the ball here but aren't most airplanes engines in the wings? If that's the case wouldn't they all have to have two to balance the plane?

He was referring to the fact the 737 has two engines as opposed to a larger aircraft which may have 4 engines.

The total fuel consumption needs to be divided by two in order for the figure to reflect each engines consumption.

mickdw

idunnoshur wrote: »

Forgive me if I'm way off the ball here but aren't most airplanes engines in the wings? If that's the case wouldn't they all have to have two to balance the plane?

Some planes have one on the tail.

Darius.Tr

I'we seen some a/c having 5 engines, whats the deal with that? Is being used or just transported from one place to another? I think it was 747

xflyer

Yes the 747 has a mounting point for transporting an engine. The engine can't be run though, transport only. It's not used much anymore. I suspect the idea came about because when those large engines were developed there were few cargo aircraft capable of taking one.

ScabbyLeg

idunnoshur wrote: »

Forgive me if I'm way off the ball here but aren't most airplanes engines in the wings? If that's the case wouldn't they all have to have two to balance the plane?

You'd be surprised at how unbalanced a plane can look, for example the Rutan Boomerang below. The designer is known for his unusual and brilliant aircraft designs. Here the balancing is done through weight distribution and the aerodynamics of the aircraft itself.

Run_to_da_hills

Darius.Tr wrote: »

I'we seen some a/c having 5 engines, whats the deal with that? Is being used or just transported from one place to another? I think it was 747

The Air India 747 200 that crashed off the Irish coast in 1985 had 5 engines.