n92r03
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How Much Fuel Is "Left Over"?

Wed Jun 20, 2012 10:09 pm

I'm amazed that one can fly anywhere on earth with just one stop. That being said, I'm also amazed at the amount of fuel it takes to do 15+ hour flights. Watching the wing flex on take-off is a real treat.

Take the UA EWR-HKG flight at appx 15.5 hours, Boeing's website shows the 772 ER has the capacity for 45k gallons of fuel. Assuming the flight is full of pax and a decent amount of cargo, would it be completely full of fuel? Today (June 20) the temperature at EWR is 97 degrees, so the flight is delayed about 4 hours until the temp cools off enough to permit the flight correct? Then, upon landing and pulling into the gate, how much fuel is actually "left over"?

I use this flight as I assume it is close to the max range. I would also be interested in any other long-haul aircraft info for the same question.

Thanks in advance-
 
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Starlionblue
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RE: How Much Fuel Is "Left Over"?

Wed Jun 20, 2012 11:01 pm

Quoting n92r03 (Thread starter):
Assuming the flight is full of pax and a decent amount of cargo, would it be completely full of fuel?

Probably not. If you fill the tanks to the brim your payload is curtailed quite a bit. You can have full payload or full tanks, not both.

Quoting n92r03 (Thread starter):
Then, upon landing and pulling into the gate, how much fuel is actually "left over"?

I think it would depend a lot on the alternate. For HKG your alternates would be something like Macau and Guangzhou. Those are both quite close. If your alternate was, say, Taipei, you'd have a lot more fuel left over when you landed.

Just taking an example from "Flying the Big Jets" for LHR-BOS on a 777. This should be somewhat representative.
Contingency: 1387 kg
Diversion: 4533 kg
Reserve: 2568 kg

Assuming you didn't use any of that, you'd have about 8½ tons left in the tanks.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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Stitch
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RE: How Much Fuel Is "Left Over"?

Thu Jun 21, 2012 5:40 pm

For DXB-LAX on an Emirates 777-200LR:

Contingency: 2600kg
Diversion (LAS): 5622kg
Reserve: 2839kg

For DXB-LAX on an Emirates A340-500:

Contingency: 2929kg
Diversion (LAS): 6366kg
Reserve: 3405kg
 
DFWHeavy
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RE: How Much Fuel Is "Left Over"?

Thu Jun 21, 2012 5:53 pm

In regards to the original poster on EWR-HKG, I believe the aircraft is quite nearly full of fuel on these flights. There likely will be little to no cargo allowed, especially when there is a full load of passengers. It is a long flight and the very edge of the envelope, the tanks would have to be pretty close to full.

As also pointed out, the summer incurs delays out of EWR because of runway length. On really hot days at or near MTOW, 11,000 ft of runway doesn't cut it.


I have a question. How often does this flight go out at MTOW?
Christopher W Slovacek
 
CO787EWR
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RE: How Much Fuel Is "Left Over"?

Thu Jun 21, 2012 8:17 pm

Would a 77L be restricted or would the GE90-115/110 be able to handle the temperature.
 
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Stitch
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RE: How Much Fuel Is "Left Over"?

Thu Jun 21, 2012 10:50 pm

Quoting CO787EWR (Reply 4):
Would a 77L be restricted or would the GE90-115/110 be able to handle the temperature.

GE does offer a "thrust-bump" option on the GE90-110b / GE90-115b that will allow an additional 3% thrust for high-ambient temperatures, though using it does shorten the maintenance interval.
 
sunrisevalley
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RE: How Much Fuel Is "Left Over"?

Fri Jun 22, 2012 1:36 am

Quoting n92r03 (Thread starter):
Then, upon landing and pulling into the gate, how much fuel is actually "left over"?

From examples I have worked on PIANO-X and from some 77W and 77L flight plans typically there is about 10% of the fuel load left assuming no diversion.
 
Viscount724
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RE: How Much Fuel Is "Left Over"?

Fri Jun 22, 2012 3:56 am

Quoting Stitch (Reply 2):
For DXB-LAX on an Emirates 777-200LR:

Contingency: 2600kg
Diversion (LAS): 5622kg
Reserve: 2839kg

For DXB-LAX on an Emirates A340-500:

Contingency: 2929kg
Diversion (LAS): 6366kg
Reserve: 3405kg

Where do you find that type of data?
 
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Stitch
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RE: How Much Fuel Is "Left Over"?

Fri Jun 22, 2012 3:54 pm

Quoting Viscount724 (Reply 7):
Where do you find that type of data?

It was posted by a Flight Operations employee at EK on PPrune.org.
 
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seabosdca
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RE: How Much Fuel Is "Left Over"?

Mon Jun 25, 2012 12:32 am

Quoting Stitch (Reply 2):
For DXB-LAX on an Emirates A340-500:

Does anyone know if that route has actually ever been flown with a 345?
 
StarAC17
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RE: How Much Fuel Is "Left Over"?

Tue Jun 26, 2012 1:05 pm

Quoting DFWHeavy (Reply 3):
As also pointed out, the summer incurs delays out of EWR because of runway length. On really hot days at or near MTOW, 11,000 ft of runway doesn't cut it.

I wonder how YYZ copes with their runways as the two longest 5/23 and 33R/15L are only just over 11,000 feet also as it in the summer can get just as hot as EWR, although the route is a tad shorter.

I guess Boeing and Airbus have the runway lengths in mind when designing for these ULH routes.
Engineers Rule The World!!!!!
 
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Stitch
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RE: How Much Fuel Is "Left Over"?

Tue Jun 26, 2012 2:30 pm

Quoting seabosdca (Reply 9):
Does anyone know if that route has actually ever been flown with a 345?

I believe EK had the 777-200LR in their fleet when they started this route, so the A340-500 might have done it as an equipment substitution, but I do not believe it was ever scheduled equipment.

That being said, EK knows what an A340-500 burns on a long-haul mission so their computer projections should be very accurate.
 
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zeke
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RE: How Much Fuel Is "Left Over"?

Tue Jun 26, 2012 2:39 pm

Quoting Stitch (Reply 11):

How many time have you operated a commercial airliner ?

There are numerous reasons why the amount of fuel carried varies between flights, even on the same type. Without explaining those differences, expressing any sort of comparison is null and void.
We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
 
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Stitch
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RE: How Much Fuel Is "Left Over"?

Tue Jun 26, 2012 4:42 pm

Quoting zeke (Reply 12):
How many time have you operated a commercial airliner?

In answer to your question, that would be never, but then these were not numbers I personally generated nor did I imply or state that they were from personal experience. So I'm not sure of the relevance of me actually having operated a commercial airliner is in terms of me posting information provided by people who do operate commercial airliners as well as those schedule them and therefore should be aware of these numerous reasons that can account for differences in fuel loads and burn.

Quoting zeke (Reply 12):
There are numerous reasons why the amount of fuel carried varies between flights, even on the same type. Without explaining those differences, expressing any sort of comparison is null and void.


Yes, I am sure that if the A340-500 went out (near) empty, it would need to carry less fuel than a (near) full 777-200LR.

According to posts by EK Flight Operations people and pilots, an EK A340-500 has a significantly higher DOW than an EK 777-200LR. An EK A340-500 also has a significantly higher fuel burn when operated on a C-Market / ULR mission than an EK 777-200LR. The EK A340-500 also looks to take a significant payload hit on DXB-LAX compared to the EK 777-200LR.

If EK felt the A340-500 was the more profitable aircraft to operate between DXB and LAX, they would have done so as EK is in the business of maximizing profit.

[Edited 2012-06-26 10:41:36]
 
OldAeroGuy
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RE: How Much Fuel Is "Left Over"?

Tue Jun 26, 2012 7:17 pm

Quoting n92r03 (Thread starter):
Then, upon landing and pulling into the gate, how much fuel is actually "left over"?

One way to get a rough idea is to compare the max landing weight to the max zero fuel weight. The increment between the two is usually set to cover the max. reserve fuel case.

This amount of reserve fuel won't be carried in every case, but it'll give an idea as to how much fuel could be left over.

Don't forget to subtract out the taxi-to-the-gate fuel. This fuel is burned out of the reserves.
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
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zeke
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RE: How Much Fuel Is "Left Over"?

Tue Jun 26, 2012 8:56 pm

Quoting Stitch (Reply 13):

The two posts do not address the various factors are that result in changes in fuel uplift required even for the same type over the same route. Even different airlines over the same route have different fuel uplift requirements. Fuel policies are airline specific.

The OP was rather specific with the route, and type in their question, your post did not address either. It does not explain the reasons between what the manufacturer calculates, and what the airline actually uses.

MFM which is normally used as a flight planning alternate for HKG only has an ILS into one end of the runway, the requirements for what is acceptable as an alternate at the flight planning stage is normally different to what is required for the planned destination. MFM also is a single runway, and has regular periods where the runway is closed for maintenance. These are just two facility related reasons why the amount of flight planned fuel will change.

The terrain around HKG, and restrictive airspace make the use of MFM operationally more difficult than it looks on paper, the two ports are only 20 nm apart. The actual distance one would fly to divert can be 4 times that. I have diverted from HKG with over 10t of fuel on-board, to land at one of the other airports in the Perl River delta with just over 4t, the flight planned fuel required for that alternate was less than 5t, including reserve. If I only had minimum divert fuel onboard at the time I commenced the diversion I would have been short by around 2t, without having minimum reserves onboard when landing.

This time of year it is also common for large frontal activity in the Pearl River to have associated TAFs which result in Wx conditions which make them unusable as alternates, this then rolls into the typhoon season which can take out an even larger area.

EK do not operate the the route, or that type on such long sectors, so I fail to see the relevance of those numbers to this thread. It reads like it is some minor point scoring exercise for your favorite manufacturer, rather than a technical response to a rather specific question in tech ops. I will enjoy your reading your contribution that actually addresses the OPs question, which related to a specific route (which attracts some specific flight planning requirements from different regulators), and a specific type.
We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
 
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Stitch
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RE: How Much Fuel Is "Left Over"?

Tue Jun 26, 2012 9:09 pm

Quoting zeke (Reply 15):
The OP was rather specific with the route, and type in their question, your post did not address either. It does not explain the reasons between what the manufacturer calculates, and what the airline actually uses.

Neither did Starlionblue's post, but whatever, I guess. *shrug*

[Edited 2012-06-26 14:10:38]
 
n92r03
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RE: How Much Fuel Is "Left Over"?

Thu Jun 28, 2012 1:41 am

Quoting zeke (Reply 15):
MFM which is normally used as a flight planning alternate for HKG only has an ILS into one end of the runway, the requirements for what is acceptable as an alternate at the flight planning stage is normally different to what is required for the planned destination. MFM also is a single runway, and has regular periods where the runway is closed for maintenance. These are just two facility related reasons why the amount of flight planned fuel will change.

The terrain around HKG, and restrictive airspace make the use of MFM operationally more difficult than it looks on paper, the two ports are only 20 nm apart. The actual distance one would fly to divert can be 4 times that. I have diverted from HKG with over 10t of fuel on-board, to land at one of the other airports in the Perl River delta with just over 4t, the flight planned fuel required for that alternate was less than 5t, including reserve. If I only had minimum divert fuel onboard at the time I commenced the diversion I would have been short by around 2t, without having minimum reserves onboard when landing.

This time of year it is also common for large frontal activity in the Pearl River to have associated TAFs which result in Wx conditions which make them unusable as alternates, this then rolls into the typhoon season which can take out an even larger area.

Those are some of the scenarios that got me thinking about it in the first place... One of the flights to HKG we came in from the north, over Macau and did a huge "360", and came around over the New Territories, Sha Tin, etc, to land. All the while I saw lightening out of the window. Thanks again for the info.

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