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Old Jul 9, 07, 1:33 pm   #1
 
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Anyone know the average cost per pound to fly 1,000 miles at $3/gallon fuel?

I read a magazine article recently that had information about how airlines were working to keep weight down and how much they saved in a year for each pound or kilo of weight they were able to shed. It was a pretty good amount although I can't remember the figure. Given the way they have started cracking down on overweight luggage it must be a real cost.

If I read the article correctly, it said half the fuel on long-haul flights (I presume trans-Pacific) was used just to carry the gas for the trip, and suggested that if fuels costs continued to rise there might be a return to the days of shorter hops for refueling.

Anyway, just curious if anyone can come up with a ballpark figure of about how much the marginal cost is to transport one pound 1,000 miles, and whether it is a significant amount. Of course, when we're talking about luggage and passengers, we're talking about more than one pound. I realize planes differ and it must be a ballpark figure.

Part two of this question, assuming it is possible to calculate a marginal cost per mile per pound (and the cost actually amonts to something), is would you be willing to fly on an airline that charged a flat fee for each seat and then charged extra for poundage, whether it be luggage or body weight. In other words, instead of pricing a round trip at $300 they might price it at $200 plus fifty cents per pound, or whatever. Needless to say a family with small children flying up to grandma's for the weekend would likely pay less per pasenger than a team of sumo wrestlers with a full load of luggage.

Personally I would like such a system because it would make everyone pay their fair share. Right now, I tend to overpack. If I had to pay for every pound I might try to pack a little lighter, which would be to everyone's benefit. Of course, I might watch my own weight a little more, too.
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Old Jul 9, 07, 5:59 pm   #2
 
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I've heard of some puddle jumper flights that weighed customers and luggage to balance the plane, but I've never been on one. I'm guessing the first airline that includes customer weigh-ins as part of its pricing and ticketing will lose all its potential female customers, and will never earn a dime thereafter.
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Old Jul 9, 07, 6:38 pm   #3
 
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Quote:
Originally Posted by deubster View Post
I've heard of some puddle jumper flights that weighed customers and luggage to balance the plane, but I've never been on one. I'm guessing the first airline that includes customer weigh-ins as part of its pricing and ticketing will lose all its potential female customers, and will never earn a dime thereafter.
You may be right, except that most women weight a lot less than men. I don't know if you've ever seen women split a bill at a restaurant, but they get it to the penny (obviously a stereotype, but more often than men). I would think they would love the chance to fly for 10 to 20 percent less.
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Old Jul 9, 07, 7:03 pm   #4
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This article reports that airlines average 49 revenue-passenger-miles per gallon of jet fuel. That's about 20 gallons per 1K miles/pax. Jet juel is about $2.10/gallon recently, so $42/pax/1K miles.

If the average pax + bags weighs 200 lbs, that's 21 cents per pound/1K miles.

Not sure how cargo fits into that equation.

And of course, that's not the marginal cost - the empty plane itself is heavy and that cost is buried here. But it's a ballpark starting point.
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Old Jul 10, 07, 9:42 am   #5
 
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Originally Posted by swag View Post
so $42/pax/1K miles.
Not even close.

$42/passenger in a 137 seat SWA 737, for example, would be $5754 in jet fuel. At your $2.10/gal figure that's 2740 gallons or 18,358 pounds. That's enough fuel to fly a 737 for over 3 hours including flying the weight of the airplane, bags, cargo, etc.
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Old Jul 10, 07, 11:39 am   #6
 
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I may have the answer using this sample chart for a 777-200:
http://www.boeing.com/commercial/air...sec3charts.pdf

The last 20,000 pounds of payload requires an extra 5,000 pounds of fuel to maintain a constant range of 3,300 nautical miles. (In other words, starting from a 100,000 pound payload, we add 20,000 more pounds to get the marginal difference for the 120,000 pound maximum payload. The chart shows that the extra 20,000 pound payload adds 25,000 pounds to the gross weight, therefore an extra 5,000 pounds of fuel was required.)

So, if a passenger has a total weight of 200 pounds, including baggage, that would require 50 pounds of extra fuel. Roughly. Converting to cost will be left as an exercise for the reader.
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Old Jul 10, 07, 12:27 pm   #7
 
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Oh, by the way, my calculation neglected to mention that it takes a little under 100,000 pounds of fuel to fly the plane with no payload. So each passenger is also reponsible for their share of that 100,000 pounds.

Last edited by Bobster; Jul 10, 07 at 12:36 pm.
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Old Jul 10, 07, 4:46 pm   #8
 
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Quote:
Originally Posted by Bobster View Post
I may have the answer using this sample chart for a 777-200:
http://www.boeing.com/commercial/air...sec3charts.pdf

The last 20,000 pounds of payload requires an extra 5,000 pounds of fuel to maintain a constant range of 3,300 nautical miles. (In other words, starting from a 100,000 pound payload, we add 20,000 more pounds to get the marginal difference for the 120,000 pound maximum payload. The chart shows that the extra 20,000 pound payload adds 25,000 pounds to the gross weight, therefore an extra 5,000 pounds of fuel was required.)

So, if a passenger has a total weight of 200 pounds, including baggage, that would require 50 pounds of extra fuel. Roughly. Converting to cost will be left as an exercise for the reader.
Bobster, you've enabled me to answer my question. If we convert the nautical miles to real miles we get about 3,800 miles. Jet fuel weighs 5.2 pounds per gallon, which I'l calculate at 5 pounds per gallon. So it takes 10 gallons of fuel to transport 200 pounds 3,800 pounds.

To get closer to my original question, It takes 1.3 gallons of fuel to transport 100 pounds 1,000 miles. By my calculation, it takes 1.664 ounces, more or less, to transport 1 pound of weight 1,000 miles. If we calculate the cost of jet fuel at $2.50 per gallon, then the cost to carry one pound 1,000 miles is 4.16 cents, at least on a 777.

At least I think that's the answer. Someone check my math and logic. Thanks Bobster for coming up with the facts.
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Old Jul 10, 07, 4:59 pm   #9
 
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I figure it's 0.25 pounds of fuel to carry 1 extra pound for the full 3300 nautical miles on a 777. Divide that by 6.7 (not 5) to get 0.037 gallons. At $3 per gallon, it would cost 11 cents per pound. So, if you want to penalize a passenger for being 10 pounds overweight, that's about a dollar.

Since the 777 isn't designed for 1000 mile flights, you'd have to lookup the graph for a more reasonable plane like the 737.

correction: Actually, it's OK to use the 777 for a 1000 statue mile flight. The problem is that it's hard read the graph that Boeing provides on their web site for that distance. It looks like a couple thousand pounds of extra fuel for the last 20,000 pounds of payload. Even though the 777 is less efficient at the shorter distance, the cost of the extra fuel required is still less than it would be on the longer flight, or less than a dollar for being 10 pounds overweight.

Last edited by Bobster; Jul 10, 07 at 5:35 pm.
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Old Jul 10, 07, 5:53 pm   #10
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Quote:
Originally Posted by LarryJ View Post
Not even close.

$42/passenger in a 137 seat SWA 737, for example, would be $5754 in jet fuel. At your $2.10/gal figure that's 2740 gallons or 18,358 pounds. That's enough fuel to fly a 737 for over 3 hours including flying the weight of the airplane, bags, cargo, etc.
So a 3.5 hour flight is what, about 1700 miles? Vs. the 1000 I estimated? That's actually kind of close. Biggest source of the discrepency is likely that the numbers I used were per revenue-pax-mile. Not sure what the average number of revenue-pax are per flight, but accounting for empty seats, award tix, deadheaders, and employees, I'll bet that explains most of the gap.

But good to see some better numbers posted.
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Old Jul 11, 07, 10:35 am   #11
 
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Quote:
Originally Posted by Rebelyell View Post
Jet fuel weighs 5.2 pounds per gallon
It's 6.7 pounds per gallon.

Quote:
Originally Posted by swag View Post
So a 3.5 hour flight is what, about 1700 miles? Vs. the 1000 I estimated? That's actually kind of close.
70% off is close? It also included the weight of the airplane and cargo, not just the passenger's weight.
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Old Jul 11, 07, 6:21 pm   #12
 
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This looks like a problem that can be solved using calculus.
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Old Jul 11, 07, 6:49 pm   #13
 
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It's not that bad...

Roughly 1.75 gallons per mile for a B737NG at about 140,000 pounds total weight. So that's 0.0125 gallons per pound per 1000 miles.
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Old Jul 11, 07, 10:03 pm   #14
 
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For the 737-900 (no winglets) I get 0.0155 gallons per pound per 1,000 statute miles.

(Payload 48,000 pounds, fuel 5,000 pounds extra compared to zero payload.)

Less than a nickel a pound.
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Old Jul 12, 07, 8:12 pm   #15
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Strangely a friend of mind sent me an email about this topc recently that I found interesting, if not a bit lacking in all the details. It comes from an AA employee, so that should (theoretically) lend some credibility to it, but judge for yourself...
Quote:
I did a little research per our discussion yesterday regarding the fuel cost of flying to LAX (one way). Note that the cost will vary from aircraft type to type, so I have included the different equipment that AA flies (though you might be hard pressed to get on a 767-200 from DFW to LAX (you could from JFK or Boston) or an Airbus A300 to fly to LAX period). The assumptions are as follows:

*All flights are 185 minutes (this is pretty much true per Sabre, our reservations software). Note that some equipment are much faster, but the scheduled (block) times are the same. (777 is about 555MPH, and MD80 is about 490 MPH).
*The carried weight is 200 lbs (this would be a 170# person with a 30# carryon bag). Of course, you can scale up or down, but that is "typical".
*The data I used is to compute the benefit of taking off x#; and I assume sufficiently straight slope to apply in negative direction.
*Today, Jet fuel is $90.30 per barrel. At 30 gallons per BBL, that works out to $3.01/gallon.

(B=Boeing, A=Airbus, PAX = number of passengers, Max)

Code:
Equipment  Gallons      Cost          4oz              PAX   Everybody
B777        17.76        $53.47        6.7 cents       245    $16.38
B767-300    19.88        $59.82        7.5             225     16.83
B767-200    20.74        $62.43        7.8             167     13.03
B757TW*     21.86        $65.80        8.2             188     15.46
B757**      21.94        $66.03        8.3             188     15.52
A300        22.78        $68.56        8.6             268     22.97
B737-800    23.13        $69.61        8.7             148     12.88
MD80        32.84        $98.85       12.4             140     17.30
* (ex-TWA, Pratt&Whitney Engines)
** (AA, Rolls Royce Engines)
You'll note that it only costs $53.50 to fly you to LAX on a 777, whereas it costs nearly twice as much ($99) to fly you there on an MD80!!! I think my estimate to you was $75-80.

If a person went to the bathroom before boarding the flight, he or she might lose 4 oz (average). The 4 oz column is the savings of just one person going to the bathroom. If everyone went to the bathroom we could save up to $23 on that one flight (actually, it would be more if I added the crew). If everyone went to the bathroom before each flight, American would save $3.1 million annually, based upon 85% full planes. So, the next time you prepare to board a flight, ask yourself, "Can I go to the bathroom first?" :-)
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