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How much extra fuel can be uplifted?

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How much extra fuel can be uplifted?

Old 4th May 2018, 08:59
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How much extra fuel can be uplifted?

Hello everyone,

Please bear with me.

In our company flight plan, the format goes like this,

R/W limited t/o weight.........79.0 ( letís say the max structural t/o is for today)
Max Ldg weight.....66.4
B/o fuel..................10.0
Ldg limited t/o weight.....76.4 (adding above two)
Max ZFW......62.7
Required fuel....13.5 (excluding taxi)
ZFW limited t/o weight....76.2 (adding above two)

planned zfw...61.0
planned t/o weight...74.5
landing weight....64.5

Now the problem Iím facing about how much extra fuel I can take for this flight. I know maximum time and easy calculation is just to subtract ldg weight from max ldg weight which gives us 66.4 minus 64.5= 1.9 tons. But in the above case we are limited by zfw limited t/o weight which is 76.2 (lowest of the three above) so should we minus this from planned t/o weight 76.2-74.5=1.7 tons. I am a bit confused here. If we take 1.9 tons then we are uplifting additional 0.2 tons here? So for the above what will be the correct answer? Thanks in advance.
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Old 4th May 2018, 23:22
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, landing weight limited
RTOW=max landing weight + trip for that sector
from this calculated RTOW deduct ZFW=max fuel you can take.
zfw weight limited, iow you cannot make MZFW because of trip length, MTOW-FUEL required(in Tanks)=LiMiting zfw
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Old 4th May 2018, 23:39
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Using 1.9 extra:

Planned ZFW = 61.0 (< Max ZFW, ok)
Fuel uplift = 15.4 (> required fuel, ok)
TOW = 76.4 (< RTOW, ok)
LdgW = 66.4 (= Max ldg weight, ok)

All looks fine to me. I don't see how the MZF limited take-off weight is actually a limit, more just advising what the take-off weight will be if you have a full payload and minimum fuel, but I don't fly your aeroplane and I don't work for your company so I may be missing something.
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Old 5th May 2018, 05:38
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When I calculate my extra fuel I do not consider the MZFW.

As you said most of the time, I consider only MLW except when the minimum required fuel is more than MTOW – MLW (here 12.6t, which represents a quite long flight) In the latter case only I consider both mlw and mtow limitation. Just be careful of overweight landing when taking the maximum extra fuel with mlw consideration, sometimes actual zfw is less than expected so optimum level will be higher and you can get shortcut…it is good for fuel saving but makes you sweating

Wondering if it’s too simplistic.
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Old 5th May 2018, 06:09
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If you go about this way it is easier to understand. Fuel reqd.13.5+61(planned zfw)=74.5 which is less than 79.0T Max structural (actually WAT limited weight). So in this case the take off weight is restricted by Max Ldg wt. You work backwards MLW limit is 66.4+10(BO)= 76.4. Your take off weight cannot exceed that. So 76.4-61(planned ZFW)=15.4T. This is the maximum fuel you can uplift. So you can take extra 15.4-13.5= 1.9T. Max ZFW is limit by itself don't confuse it with RTOW.
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Old 5th May 2018, 08:22
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Thanks for the replies.
If we take 1.9 tons of extra in this case so basically we are limited to our 'planned' zfw which means we can not take any more extra load? 13.5+61.0+1.9= 76.4 (minus burn off gives us 66.4). We are absolutely limited by planned zfw. No additional LMC. Whereas if we took 1.7 tons extra that is (max zfw minus req) we could get 0.2 extra load? I am with the consideration of max ldg wt to be the limiting factor GIVEN we will not exceed planned zfw. My calculations,
(LDG wt + b/o) - planned zfw - req fuel = max fuel that can be uplifted
My another question is then why are we calculating Max ZFW plus Req fuel
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Old 5th May 2018, 08:29
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Theoretically, you would be able to load slightly more than 1.9 t extra, because there will be a burn-off penalty due to the additional weight as compared to the original planned take-off mass.
Most OFPs will show the burn penalty for every extra 1000 kg loaded?
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Old 5th May 2018, 11:57
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Forget MZFW TOW limit - it is simply a nonsense. It is not a limit unless your airline, for whatever weird reason, has chosen to make it a limit.

You can add fuel until you reach one of your calculated limits for today's flight or a structural limit. Today it's 1.9T extra from LDW limited TOW. You will, of course, have a slightly greater sector burn due to the increased weight but it would be tiny. Keep it for a bit of a margin if your flight time is a bit less.
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Old 5th May 2018, 12:38
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I have no idea why you are calculating MZFW plus required burn. All I can think is to check that this figure does not exceed your RTOW because then you just can't go at all.

In general, the way I do it is this.

The difference between max landing weight and max zero fuel weight is the absolute most fuel I can plan to land with while still providing the company with maximum payload. If I know the payload then I can increase the extra fuel to the difference between MLW and actual ZFW. If I have a rough idea of the payload but it may change a little, then I would use the difference between MLW and actual ZFW but with a bit of a buffer.

On my type, the vast majority of the time, the difference between MLW and MZFW is ample arrival fuel, so I can usually take the fuel I want and preserve max payload.

In your example, if you take 1.9T extra then yes, you are at your landing weight limit and can't take any extra payload.

Originally Posted by carnival30 View Post
Thanks for the replies.
If we take 1.9 tons of extra in this case so basically we are limited to our 'planned' zfw which means we can not take any more extra load? 13.5+61.0+1.9= 76.4 (minus burn off gives us 66.4). We are absolutely limited by planned zfw. No additional LMC. Whereas if we took 1.7 tons extra that is (max zfw minus req) we could get 0.2 extra load? I am with the consideration of max ldg wt to be the limiting factor GIVEN we will not exceed planned zfw. My calculations,
(LDG wt + b/o) - planned zfw - req fuel = max fuel that can be uplifted
My another question is then why are we calculating Max ZFW plus Req fuel
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Old 5th May 2018, 15:00
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My another question is then why are we calculating Max ZFW plus Req fuel
No! We don't. RTOW can restrict ZFW. ZFW doesn't restrict RTOW. Because when RTOW is restrictive you cannot reduce required fuel so only ZFW has to be reduced. Just go the way I said in my earlier post.
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Old 5th May 2018, 16:11
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After reading your last post only I understand better your question. Can you add load after refueling completed if the fuel quantity you took with the initial zfw will make you land at mlw? If yes how much?

Yes you can, but you have to burn the equivalent weight of fuel in order to land at mlw (by holding or by flying at lower level, etc...) Off course not exceeding the mtow.
How much? As much as you want as long as it is less than mzfw, here 62.7t.

Actually I think the terms you use are not very appropriate so that's why it is mixed up a bit like "limited by planned zfw" "ZFW limited t/o weight" ... there is only one structural limitation of zfw which is the mzfw.

Hope it helps.
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Old 5th May 2018, 16:19
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Just for precision, if you accept an extra last minute load more than the LMC approved by your company policy, you have to change the fuel trip also otherwise you will exceed the mlw in your load sheet. So you add your fuel trip the weight you have accepted at last minute.
And off course...it has to be in accordance with your fuel policy.
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Old 5th May 2018, 16:26
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Thanks guys! Lot of things got cleared.
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Old 5th May 2018, 16:53
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Yes you can, but you have to burn the equivalent weight of fuel in order to land at mlw (by holding or by flying at lower level, etc...)
No! You can't. Arithmetically possible but not legally. RTOW Landing weight limited means just that. It is applicable for takeoff. You cannot legally exceed that and then burn extra to get within MLW.
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Old 5th May 2018, 23:22
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Originally Posted by vilas View Post
No! You can't. Arithmetically possible but not legally. RTOW Landing weight limited means just that. It is applicable for takeoff. You cannot legally exceed that and then burn extra to get within MLW.
Perhaps not, but you can adjust the calculated burn prior to take-off so the figures work. Then you just have to burn what you said you were going to. Fly a lower level or something.
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Old 6th May 2018, 01:59
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I think you can. If it is arithmetically good you can make it legally good. How? By increasing the planned trip fuel or if company policy allows by increasing the planned trip and taxi fuel (on the loadsheet)
I just want to make me clear again to avoid misunderstanding, common sense should be used about the quantity (I am not talking about tons of last minute load but about 2 or 3 passengers)
Remember, the figures on the loadsheet are not the real ones, so if it shows that you land at 63,324t in real it will be more than that or less than that depending on the actual weight of every passenger. You may have easily 100 or 150 kgs difference.
However, when I plan my extra fuel because of bad weather or traffic or whatever, I try to keep the planned ldw at a maxi of 1t or 500 kgs less than the mlw to have margin in case of shortcut which is very common in some areas.
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Old 6th May 2018, 14:29
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vilas,

I am not quite sure why you say, 'No! You can't.'

Back in the 1970s, when James Mancham was President of the Seychelles, I was flying a VC10 to the island from Nairobi. There was a large load of fruit and veg in the hold, plus a goodly load of passengers. Mombasa was the fuel alternate and all this put us over the max landing weight at Seychelles, the only remedies were either to offload the fruit and veg or offload some passengers, neither of which seemed a good idea - so, I decided to burn the excess fuel off on the way so as to be below MLW.

President Mancham was on board in first class and when, en-route, I went back to talk to the passengers (we did in those days) I explained the problem and asked him if he would like to see his island. He was delighted at the idea, so I sat him in the jumpseat and we flew round the island at around 500ft and burnt off the excess fuel. Both he and the passengers on the left side were very happy.

So - all legal with problem solved and good diplomacy and publicity achieved at the same time!

Last edited by Bergerie1; 6th May 2018 at 17:18.
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Old 6th May 2018, 17:29
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Originally Posted by vilas View Post
No! You can't. Arithmetically possible but not legally. RTOW Landing weight limited means just that. It is applicable for takeoff. You cannot legally exceed that and then burn extra to get within MLW.
I was on a flight recently where the undercarriage was lowered for about 20 minutes in the cruise in order to burn off excess fuel that had been loaded by mistake before we had departed, so clearly it is possible.
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Old 6th May 2018, 18:15
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Bergerie and dastocks
I hope you are aware that one of the conditions of RTOW is landing weight limit. It is not a question of what you did or what is possible. RTOW Landing wt. Limited is legal limit for takeoff weight. What you did violates that. Just because you landed below max Landing weight it doesn't absolve that. Then why have this limit at all? Secondly why burn extra fuel just follow overweight landing procedure. It doesn't make any sence. At take off as long as your flight plan BO shows you are over landing weight it is violation. In landing weight limited scenario sometimes you don't burn contingency fuel and may end up overweight at destination. In that case you can burn that extra to land within max ldg wt it's ok.
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Old 6th May 2018, 20:05
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Hi guys,
I tend to agree with what vilas says. Load-sheet is a legal document that remains accessible to the dgca for a couple of years.
It can not show a planned overweight landing.

Choosing to burn extra fuel or performing overweight ldg proc is another story. Everyone will decide.
But as far as I know, it's also a limitation. So I would prefer to burn it.

Concerning the very first question. Max FOB is 15.4 + taxi fuel.

Last edited by Feather44; 6th May 2018 at 20:17.
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