Topic Author
Posts: 117
Joined: Wed May 11, 2005 5:03 am

On Airlines, Aircraft And Fuel

Folks, I'm looking to see information and discussion on the subject of fuel with regards to the airlines and their aircraft. I had thought I understood a fair bit about it, but find that assumption may be flawed and am looking for your help and knowledge. Some questions (in no particular order) to point the discussion:

Is there a standard for the purchase of fuel which most airlines use, or is there a variety?

When airlines have their aircraft fueled prior to flight, what are some of the most important variables involved? How much of a role, if any, does cost play a factor?

Is there an average or a standard for how many cycles an aircraft can/will undertake between fuelings?

I look forward to the discussion; thank you for your time and effort!
TANSTAAFL!

Starlionblue
Posts: 17579
Joined: Fri Feb 27, 2004 9:54 pm

RE: On Airlines, Aircraft And Fuel

 Quoting NADC10Fan (Thread starter): Is there an average or a standard for how many cycles an aircraft can/will undertake between fuelings?

For long-haul, you always fuel every cycle. No other way is possible.

Ideally, you want to fuel the plane each cycle, since otherwise you're burning (quite a lot of) fuel just to carry more fuel.

One exceptionis when the turnaround is very short, but fueling is normally faster than debarkation/boarding anyway.

Another exception is brough about by fuel prices variations. In the southern US, fuel might cost significantly less, making it worth carrying fuel for two flights (from and to the cheap fuel).
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo

Topic Author
Posts: 117
Joined: Wed May 11, 2005 5:03 am

RE: On Airlines, Aircraft And Fuel

 Quoting Starlionblue (Reply 1):For long-haul, you always fuel every cycle. No other way is possible. Ideally, you want to fuel the plane each cycle, since otherwise you're burning (quite a lot of) fuel just to carry more fuel.

By "long-haul," I would expect we're speaking either transcontinental or intercontinental routings? Are there shorter examples beyond which an airline would always refuel between cycles?

 Quote:One exception is when the turnaround is very short, but fueling is normally faster than debarkation/boarding anyway. Another exception is brough about by fuel prices variations. In the southern US, fuel might cost significantly less, making it worth carrying fuel for two flights (from and to the cheap fuel).

How prevalent would you say this practice may be? Is there commonly such variance in fuel prices between such relatively nearby destinations to warrant the cost incurred for a higher first take-off weight in order to save having to fuel at such a destination? What sorts of capability exist for multiple cycles between refuelings (i.e. more than two landings before the next refueling)?
TANSTAAFL!

Starlionblue
Posts: 17579
Joined: Fri Feb 27, 2004 9:54 pm

RE: On Airlines, Aircraft And Fuel

 Quoting NADC10Fan (Reply 2):Quoting Starlionblue (Reply 1): For long-haul, you always fuel every cycle. No other way is possible. Ideally, you want to fuel the plane each cycle, since otherwise you're burning (quite a lot of) fuel just to carry more fuel. By "long-haul," I would expect we're speaking either transcontinental or intercontinental routings? Are there shorter examples beyond which an airline would always refuel between cycles?

 Quoting NADC10Fan (Reply 2):Quote: One exception is when the turnaround is very short, but fueling is normally faster than debarkation/boarding anyway. Another exception is brough about by fuel prices variations. In the southern US, fuel might cost significantly less, making it worth carrying fuel for two flights (from and to the cheap fuel). How prevalent would you say this practice may be? Is there commonly such variance in fuel prices between such relatively nearby destinations to warrant the cost incurred for a higher first take-off weight in order to save having to fuel at such a destination? What sorts of capability exist for multiple cycles between refuelings (i.e. more than two landings before the next refueling)?

You'd have to do the math for both of these, but obviously if you take your average short/medium haul jet (let's say a 737-800) and fly 1ï¿½ hour segments (let's say by Ryanair) you are not even close to half of the max endurance. So technicaly you would have no problems flying even three segments without refueling. But carrying all that fuel around for no good reason will burn a lot of fuel and can be likened to tossing ï¿½100 bills on a fire.

I would say most airlines fuel every cycle, except if the airport is a bit short of refueling capability (LCY?) or the fuel is MUCH cheaper at one end. I could be wrong though. Why don't you ask the real propellerheads over in Tech/Ops?

For medium/long haul (over 4-5 hours), the cost of carrying fuel for both legs becomes prohibitive. I think PhilSquares (who flies the 747) once mentioned that for every extra 1000kg of fuel you have to carry 6 hours, you use 300kg just to carry it. I could have the numbers wrong but in any case it was a lot of money.

[Edited 2005-09-27 22:20:53]
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo

OPNLguy
Posts: 11191
Joined: Tue Jun 15, 1999 11:29 am

RE: On Airlines, Aircraft And Fuel

 Quoting NADC10Fan (Thread starter):Is there a standard for the purchase of fuel which most airlines use, or is there a variety?

I'm not quite sure about your question; "standard" in what context? Fuel tech specs? (Jet-A)

 Quoting NADC10Fan (Thread starter):When airlines have their aircraft fueled prior to flight, what are some of the most important variables involved? How much of a role, if any, does cost play a factor?

The main variables are the stage length of the flight involved, and enroute weather (and any fuel needed for deviations or altitude changes), winds and tempts aloft,weather at the destination (and any required alternate plus fuel to reach it) plus holding fuel and fuel for any MEL/CDL-related penalties.

 Quoting NADC10Fan (Thread starter):Is there an average or a standard for how many cycles an aircraft can/will undertake between fuelings?

This is largely a variable of the stage lengths involved and the payloads of each flight. On such short flights, the limiting factor weight-wise isn't a takeoff limitation, but a max landing weight limitation. If a flight is to operate A-B-C-D (all on short hops) it may be possible to fuel up at A such that you can get all the way to D without refueling, but things have to line up just right. It's more likely to be possible if the weather is good on all the segments (no alternate fuel thus required, as above), and if payloads are reasonable, i.e. not full. You're also more likely to do it if any "full" flight is on the back end of the sequence. If you're full on the A-B segment, you're almost certainly going to run into the MLW limitation and not be able to fuel all the way to D.
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.

legacy135
Posts: 966
Joined: Sat May 14, 2005 11:06 pm

RE: On Airlines, Aircraft And Fuel

In regard to fuel prices, it is a point, where the operator can save a lot of money or as well spend quite a bit. The thing is, prices vary a lot all over the world. You may even find big differences in prices between two different suppliers on the same airport. Airlines do work a lot on contract base with suppliers and deal out there prices.

As Starionblue already stated correctly, it is the most economic to carry the minimum. With every kilo you carry more, you brun more. On the other hand it may be cheaper to transport cheap fuel, if you have a "cheap source".

For corportae operators or charter companies, flying to places they don't have a deal set up, is the possibility to work with an agent. They give you fuel cards and have contacts all over the world. Companies as BP, Multiservice, UVair, Avcard are some names in this business. Here again, the prices may vary between different suppliers. Let me give you some examples:

Prics per 1000 US Gallons in US \$, valid today, 27. 09. 2005

Ft Lauderdale FLL:

National Jet, payed by UVair 306.59
Jetscape, payed by Avcard 280.00

Amsterdam AMS:

Texaco, payed by UVair 220.76
KLM, payed by UVair 242.00
Statoil payed by Avcard 190.00
Q8, payed by Avcard 207.45
Air Total, payed by Multiservice 186.00
KLM, payed by Multiservice 256.00

Dubai DUB:

ENOC, payed by Avcard 207.57
Air BP, payed by Multiservice 229.00
Air BP, payed by UVair 230.33

Stuttgart STR:

Shell, payed by UVair 368.29
Exxon, payed by Avcard 368.00

You see, there is quite something in the price....

As an example, I can give you, that we pay at the moment in Bern BRN an average of 380.00 per 100 US Gallons. On the other hand, in Tunis TUN still an average of about 200.00 per 100 Gallons. If I fly the E135 on minimum fuel from TUN-BRN I burn about 1800 Kilos for the trip, which lasts about 1:45. If I go with the maximum possible, I burn about 2000 kilos for the same trip, maybe 10% or so more. On the other hand, I will land with 5000 kilos left at a price which is nearly half price!

So you see, it is strongly dependable from the individual situation. Apart from economical aspects we should not forget all the operational and safety aspects. If the weather is great I can go with much less as if we do face the possibility of severe delays or even reroutings do to weather. If the runway is wet, it may be a good idea to land with a lower weight than on a dry one.

What the law says, is that we need to carry the following:

- the fuel we go to burn on the trip, plus 5%
- the fuel to hold 30 minutes (45' with piston aircrafts)
- the fuel to fly to the alternate
- the fuel to fly a go around and another approach at the alternate

The total of this figures is called "Minimum Block Fuel". In additon to this the crew may/needs to add all the factors mentioned above and anything else, that could affect a safe and economic operation. What finally results is called "Actual Block Fuel" and is what the Captain wants to see on board.

Topic Author
Posts: 117
Joined: Wed May 11, 2005 5:03 am

RE: On Airlines, Aircraft And Fuel

Guys, thanks much for posting your thoughts on the subject; I most definitely appreciate them!

Legacy, I'm not quite sure I understand the example you're giving of the BRN-TUN round trip. Which is it originating in? If TUN, then it would be understandable to me that you would fully fuel there, turn around in BRN without doing so and return to TUN. Is that what's happening? (Apologies if I have it turned around.)

Also, was looking at the fuel prices that you mentioned - do I understand correctly that those are what are paid by private/charter currently in those locations? Or by the airlines? Or both?

OPNL - the "standard" I was referring to (if such it is) is the manner in which the airlines purchase fuel. I am honestly in the dark as to the reality of this. I know that WN, for example, employs a hedging strategy where they negotiated years ago for their prices to remain static for a term of x years (I believe that agreement expires in '07)? How prevalent is this - the most common (i.e. standard)? If not, what other such strategies are used, and which is the most common?

Starlion, OPNL - your points on modern a/c being capable of multiple stops without refueling is well-taken. It sounds as though the rule is that - while you don't necessarily carry only enough fuel to get to a place (unless you're flying long-haul) - you generally at least top off your tanks at a given stop. Is that a fair-enough expression of how it generally works?
TANSTAAFL!

OPNLguy
Posts: 11191
Joined: Tue Jun 15, 1999 11:29 am

RE: On Airlines, Aircraft And Fuel

 Quoting NADC10Fan (Reply 6):Starlion, OPNL - your points on modern a/c being capable of multiple stops without refueling is well-taken. It sounds as though the rule is that - while you don't necessarily carry only enough fuel to get to a place (unless you're flying long-haul) - you generally at least top off your tanks at a given stop. Is that a fair-enough expression of how it generally works?

You almost never top off the tanks. Generally speaking, you fuel for the mission, i.e. the specific flight, and some flights may "tanker" extra fuel if the fuel costs less at the takeoff airport and costs more at the destination airport. Our computers figure this out, and take into consideration the fuel consumed by carrying the extra fuel weight from A-B.

And a note on fuel hedges. SWA pays the same thing everyone else does for fuel. What the hedges are are various financial instruments, the profits from which offset the cost of the fuel we buy. Various levels of hedges are in effect through 2009. There was a separate thread on hedging recently, so a search will give you alot more info on this.
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.

legacy135
Posts: 966
Joined: Sat May 14, 2005 11:06 pm

RE: On Airlines, Aircraft And Fuel

 Quoting NADC10Fan (Reply 6):Legacy, I'm not quite sure I understand the example you're giving of the BRN-TUN round trip. Which is it originating in? If TUN, then it would be understandable to me that you would fully fuel there, turn around in BRN without doing so and return to TUN. Is that what's happening? (Apologies if I have it turned around

This fuel can be used to go anywhere. With a load as high as 5 tons I could do a flight as far as Cairo CAI without fueling in BRN. The idea is to carry as much of the cheap fuel as possible in order to avoid an expensive uplift.

 Quoting NADC10Fan (Reply 6):Also, was looking at the fuel prices that you mentioned - do I understand correctly that those are what are paid by private/charter currently in those locations? Or by the airlines? Or both?

This is correct, as long as they use the agents mentioned for payment. If an airline serves any of these destinations with a high number of flights, they will go and deal out their own prices with the suppliers. It will be cheaper then. Imagine a situation like Southwest in Houston Hobby. They basically control the market there and I am sure, they tell the suppliers pretty much what the price is

Starlionblue
Posts: 17579
Joined: Fri Feb 27, 2004 9:54 pm

RE: On Airlines, Aircraft And Fuel

 Quoting OPNLguy (Reply 7): And a note on fuel hedges. SWA pays the same thing everyone else does for fuel. What the hedges are are various financial instruments, the profits from which offset the cost of the fuel we buy. Various levels of hedges are in effect through 2009. There was a separate thread on hedging recently, so a search will give you alot more info on this.

Actually fuel hedges are insurance poliies against price fluctuation. While the actual construction of the total risk profile can be very complex, the principle is that the fuel buyer buys a fuel future (that is, a promise to be able to buy at price x at time y) from the fuel seller. The buyer is betting that the price of fuel at time y will be larger that x + the price of the future. The seller is betting the opposite, and/or that the profit from getting the deal makes it all worth it.

Of course, the seller will no hedge (his bets) by, for example, buying an option on fuel. This is an option so it does not have to be exercised (used). the seller can cover some of his risk.

It becomes very complex, but traders try to calculate how they are exposed to risk according to their wishes. Some companies are more risk exposed than others, and will hedge in some way dependent on it.

I could explain better, but I would need a whiteboard   I used to work in the financial industry, and my wife still does. It gets very complex very fast.

If you really really want to learn about all this stuff, I recommend Brealey-Myers: Principles of Corporate Finance, a lot of paper and a few weeks of your time
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo

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