How much extra fuel can be uplifted?
 

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.

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.

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.

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?

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.

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.

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.

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.

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.

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.

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.

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!

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.

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.

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.

vilas, Feather44
If you change the trip fuel on the loadsheet you solve the legal issue. But then you have to burn it in real.

Feather
you're absolutely correct. I am not suggesting OW landing that is also a limitation just trying to show the incorrectness of planning OW landing RTOW. And new_era I already said that BO needs to be adjusted. The one that got away doesn't make anything legal.

new era, Yes, I understand your point.
Unfortunately, I don't believe we are allowed to round numbers on our own.
I suppose it must be documented. Which means you need a new CFP to show the new figures for fuel trip or taxi fuel.

Of course not doing so will probably go unnoticed. Until a poop hit the fan and dgca start to investigate.

Important thing to understand is that RTOW Ldg Wt Ltd. is a regulatory takeoff weight limitation and it legally controls takeoff weight it has nothing to do with what weight actual landing is carried out. This is not an arithmetical exercise.

I'm very interested about the RTOW Ldg Wt Ltd you are talking about. Can you please elaborate by giving an example?

vilas,

As I remember it (it was a long time ago) it was only necessary to sign a section on the load sheet declaring that the excess would be burnt off before landing. Perhaps the law has changed or perhaps captains were allowed more discretion in those days.

vilas,
Correct. But you may increase the planned burn by choosing to fly faster, lower or even holding to ensure Landing Weight is not exceeded.

Bergerie1

If you required a certain amount of fuel to get to the Seychelles and then have enough to divert to Mombasa and this put you overweight at the Seychelles surely by burning off fuel to get to the landing weight at Seychelles you would be below the legal requirement to reach Mombasa has a last minute incident closed the Seychelles airport.

I suspect the only legal solution would have been to reduce the traffic load ex Nairobi.

bar none,

The weather was CAVOK, and no other traffic - I checked with ATC. Yes, I agree my decisons may have been legally marginal but they were safe.

Why is holding to Land at Seychelles with min reserve + lots extra fuel at Max Landing weight less legal than diverting to Mombassa and arriving with min reserves?

Golden Rivet,

I totally agree! This conversation has become ridiculous - all common sense has gone out of the window.

Hi Bergerie1,
The rules sill make common sense. It's just some crew's flawed interpretation.
We used to operate to BDA with Island Reserve fuel plans. i.e. Arrive overhead BDA with the ability to hold for 90 mins and no where else to go.
https://www.pprune.org/questions/848...-airfield.html

Goldenrivett,

Yes we did that too - many times. And this thread has made me think back a bit. I forget the likely fuel figures I would have had to play with - lost in the mists of time I fear! I guess I would have had to burn off about 20 to 30 mins of fuel after arriving at the field. Whether I would have had the equivalent of Island Reserve I don't recall, but it must have been close to the required amount.

What concerns me about the discussion on this thread is the lack of lateral thinking. Is everyone these days blinkered by strict rules, SOPs and overbearing managements?

Bergerie1,

It’s a bit like the story of two Flights A and B with no weather problems at their destinations.
A plans to go to airfield Z with airfield Y as the Alternate. B plans to go to Y with Z as the Alternate. Flying time between Y and Z is say 30 mins.

Both A and B arrive at their intended destinations at the same time and due to some airfield delays have to hold for say 20 mins.
Both are now down to their Reserve + Diversion Fuel. ATC advise of a further 5 mins delay, then both airfields will be open.
Do they continue to hold at their respective destinations or divert?

If they divert, then A and B will pass each other halfway between Z and Y and both will arrive at their respective Alternates with only Reserve fuel remaining.
If they both continue to hold at their respective destinations for a further 10 mins say, then both will land with Reserves + most of their Diversion Fuel remaining.

Which option is safer? (Both are legal).

Bergerie1
Rules, SOPs and overbearing management are different things. When it comes to regulatory requirements there is simply no option but to follow them. Breaching SOP and management decisions may cause a reprimand or at worst loss of that job but you still have the license you can go somewhere else. Person who operates within regulatory requirements is not blinkered but is disciplined and knowledgeable. I have not seen any rule that allows you to simply sign that you will burn the extra and breach RTOW requirements.
New_era I don't know which aircraft you fly but if it is airbus then open the performance training manual and you will see that there two requirements at destination that limit your take off weight. It is clearly written on page 74: MTOW is the lowest of:
1. Max Take off weight due to limiting landing weight at destination.
2. Max take off weight due to limiting go round weight at destination.
3. Limiting performance take off weight( obtained with Regulated Takeoff Weight charts.)
All the conditions are simultaneously applicable. You cannot violate the first two for take off by saying we will manage later for landing.
Yes! you can cheat by showing higher fuel burn. But I don't see any logic in picking up more fuel only to burn by flying low. Especially in the original post for extra 200kgs.

Vilas,

Thank you very much for explanation. I’m on the 737NG. I got your point now about the limitation. Yes we do have also these performance limitations (field length, go around, obstacle, …) and the structural limitation.

Please! Please! It is not about cheating or doing illegal thing.

As AerocatS2A said it is in the case that refueling is completed and you expect to land at mlw (performance or structural)

Consider my following example (original post figures) considering ONLY structural limitaion:

zfw…61

fob…15.4 (13.5 +1.9)

tow…76.4

trip….10 (FL350)

ldw…66.4

Then you have last minute 4 pax (90 x 4 = 360 kgs) Is it arithmetically and legally possible to take them? YES

How? Change to cruise at FL 310. Rule of thumb, if you fly 4,000 ft below the optimum you will burn roughly 5% more fuel (FPPM p2.1.1)

Figures become:

zfw…61.4 (+4 pax)

fob…15.4 (13.5 +1.9)

tow…76.8

trip….10.5 (FL310)

ldw…66.3 (even less than mlw)



Now please tell me, where is the cheating, where is the illegal thing on it.