PDA

View Full Version : How much extra fuel can be uplifted?


carnival30
4th May 2018, 09:59
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.

sjimmy
5th May 2018, 00:22
, 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

AerocatS2A
5th May 2018, 00:39
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.

new_era
5th May 2018, 06:38
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.

vilas
5th May 2018, 07:09
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.

carnival30
5th May 2018, 09:22
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

Stanley Eevil
5th May 2018, 09:29
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?

mustafagander
5th May 2018, 12:57
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.

AerocatS2A
5th May 2018, 13:38
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.

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

vilas
5th May 2018, 16:00
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.

new_era
5th May 2018, 17:11
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.

new_era
5th May 2018, 17:19
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.

carnival30
5th May 2018, 17:26
Thanks guys! Lot of things got cleared.

vilas
5th May 2018, 17:53
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.

AerocatS2A
6th May 2018, 00:22
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.

new_era
6th May 2018, 02:59
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.

Bergerie1
6th May 2018, 15:29
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!

dastocks
6th May 2018, 18:29
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.

vilas
6th May 2018, 19:15
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.

Feather44
6th May 2018, 21:05
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.

new_era
7th May 2018, 02:26
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.

vilas
7th May 2018, 04:10
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.

Feather44
7th May 2018, 04:39
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.

vilas
7th May 2018, 05:16
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.

new_era
7th May 2018, 05:57
I'm very interested about the RTOW Ldg Wt Ltd you are talking about. Can you please elaborate by giving an example?

Bergerie1
7th May 2018, 06:22
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.

Goldenrivett
7th May 2018, 08:48
vilas,
Important thing to understand is that RTOW Ldg Wt Ltd. is a regulatory takeoff weight limitation and it legally controls takeoff weight
Correct. But you may increase the planned burn by choosing to fly faster, lower or even holding to ensure Landing Weight is not exceeded.

wiggy
7th May 2018, 09:04
As you say..there will be a legal requirement that one should not produce a load sheet with illegal landing weight figures. OTOH even in these days of the computer saying “no” upstream of loadsheet production there are ways of generating a Trip Fuel that produces a legal landing weight figure.

bar none
7th May 2018, 11:39
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.

Bergerie1
7th May 2018, 11:54
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.

A and C
7th May 2018, 12:15
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.

unfortunately common sense has now left the building.

Goldenrivett
7th May 2018, 12:24
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.
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?

Bergerie1
7th May 2018, 12:30
Golden Rivet,

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

Goldenrivett
7th May 2018, 13:10
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/84816-minimum-fuel-required-no-destination-alternate-isolated-airfield.html

carnival30
7th May 2018, 13:50
We can plan to burn extra fuel BUT legally it can not be documented as Vilas said. Common sense or not, a flight can not depart with a flight plan that says OW landing at destination. Boeing fctm has a different section on OW ldg and it will do fine but that does not mean we can plan overweight landing or plan to burn excess fuel BEFORE departure deliberately in order to achieve ldg wt limitation at destination. If you plan to burn more than normal burn off by choosing different altitude or speed/mach etc then the additional burn off gets to add in the total burn off in the flight plan so I dont know how its possible to document the additional burn off for legal purpose

Bergerie1
7th May 2018, 15:40
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?

Goldenrivett
7th May 2018, 16:29
Bergerie1,

Itís 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).

vilas
7th May 2018, 18:49
Bergerie1
Is everyone these days blinkered by strict rules, SOPs and overbearing managements? 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.

AerocatS2A
7th May 2018, 23:39
You don’t do it so you can take extra fuel, you do it when your payload is higher than expected or perhaps you got over-fueled. Given a choice of offloading a couple of pax, de-fueling the aircraft, or revising the burn to make the load sheet work, I’d take the latter.

new_era
8th May 2018, 01:23
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.

Vessbot
8th May 2018, 04:09
Now please tell me, where is the cheating, where is the illegal thing on it.

This is legitimate, as long as you actually replan for 310 and get a load sheet that gives a good landing weight at/below the limit. (Or, in the case of my airline, this isn't shown directly but there's just a takeoff weight that is predicated on that.)

What's illegal is to just say "we'll burn it off in the air" and take off at the higher weight without replanning.

"Cheating," depending on the slang of where you're from, may refer to something that's legitimate but involves a clever work-around an initial obstacle; i.e., it could be either one of the above two actions.

vilas
8th May 2018, 04:18
The point I have been making is that Regulatory Takeoff Weight has limitation that arise from approach and landing part. What you intend to do at landing is not enough the loads sheet before takeoff must reflect that it fulfills those (RTOW) requirements.

new_era
8th May 2018, 05:19
Can you give an example using the same figures in what case the limitation you are talking about is violated?

zfw…61.4 < mzfw
tow…76.8 < mtow
ldw…66.3 < mlw

vilas
8th May 2018, 14:14
Bergerie 1
So - all legal with problem solved and good diplomacy and publicity achieved at the same time! I am afraid I have to disagree. There are many occasions when civil aviation authority officials come on board after landing and check the fuel remaining. They don't want to to know your story but want to see in tanks alternate fuel+30min holding fuel at alternate. If you didn't have that you would be hauled over coals. If an airline repeats such incidents their AOP is in danger.

Goldenrivett
8th May 2018, 16:08
vilas,
They don't want to to know your story but want to see in tanks alternate fuel+30min holding fuel at alternate. If you didn't have that you would be hauled over coals.

Not true!
Have a read of the recognised procedures when you are "committed" to a single airfield.
http://www.ifalpa.org/downloads/Level1/Briefing%20Leaflets/Air%20Traffic%20Services/13ATSBL01%20-%20ICAO%20changes%20for%20minimum%20and%20emergency%20fuel.p df
or
https://publicapps.caa.co.uk/docs/33/InformationNotice%202015082.pdf

Company procedure is to file an ASR so any trend can be monitored.

pineteam
9th May 2018, 05:43
I agree with Goldenrivett on this one. We discussed about it recently in this thread: https://www.pprune.org/questions/607266-flying-b-minimum-fuel.html

vilas
9th May 2018, 06:48
Golden rivette and Pineteam
If you read carefully the reference you have given it only confirms what I am saying. You are supposed to keep track of fuel consumption all along in cruise and you are supposed to divert before minimum fuel situation arises. You cannot burn extra fuel to create a situation to commit to land and claim the privilege of minimum fuel. Incidently at Heathrow they have checked minimum fuel on board after landing.

Goldenrivett
9th May 2018, 08:54
vilas,
you are supposed to divert before minimum fuel situation arises.
If landing is assured at your destination (no weather problems etc) what is the advantage of diverting to an airfield with a single runway and arriving with only 30 mins of fuel remaining?

B737900er
9th May 2018, 09:26
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.
Under EASA you are allowed to depart if the Expected landing weight (dispatch) exceeds the required weight for landing performance. You will need to file two alternates.

Inflight - The expected landing weight must be at or below the landing perf limit weight.

pineteam
9th May 2018, 12:24
vilas,

If landing is assured at your destination (no weather problems etc) what is the advantage of diverting to an airfield with a single runway and arriving with only 30 mins of fuel remaining?

Yes. Does not make any sense. Better to cancel alternate fuel and hold. The crew has to monitor the fuel during flight not to land with less that minimum legal fuel which is 30 min at holding speed at 1500 feet AAL. Not a situation anyone wants to be but landing with only 30 min of fuel in the tank is 100% legit. Below that, no question asked, the crew must call Mayday Fuel.

vilas
9th May 2018, 12:50
Goldenrivett
Far too many variations have got in the original question and we are going around in circles. IFR flight/VFR flight, Alternate required/not required/not available, remote destination all these situations have different fuel requirements, we can't discuss all in one breath. I was referring to Bergerie1. His RTOW calculation at Nairobi was incorrect. Period! Refusing some payload or passengers is always a bad idea but you have to do it many times otherwise Regulated Takeoff Weight will become a joke. You have no option unless you manipulate the BO. I do not want to repeat what I have already stated. I don't know how any one can justify doing unplanned low flying with passengers and a VIP/Semi VIP on board and claim a pat on the back.You can check weather and traffic but ask Sully he will tell you cannot check for birds. Then you burn fuel and along with it your diversion and claim privileges of a committed landing. And despite my quoting Airbus manual page number B737900er states EASA doesn't have landing weight limit. May be AIRBUS doesn't form part of EASA.

bucks_raj
9th May 2018, 14:52
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.


THERE IS ONLY ONE WAY TO DO THIS.... Which is sorry.... THAT IS the RIGHT WAY!!

MZFW+TakeOff Fuel
MLW + Trip (Takeoff Roll to Landing Roll or Burnoff - Taxi)
MTOW
Performance Limited Takeoff weight from RTOW Charts or Software

Calculate the above four numbers --->> Choose the Smallest of Them all --->> Smallest number - ZFW + Taxi Fuel = The amount of fuel you can carry

If the amount of fuel you can carry is fixed due to destination weather or enroute weather or any other reason in that case -->> Smallest Number - Fuel + Taxi Fuel = YOUR Max Zero Wt

Period ...

new_era
9th May 2018, 17:46
Goldenrivett
Far too many variations have got in the original question and we are going around in circles. IFR flight/VFR flight, Alternate required/not required/not available, remote destination all these situations have different fuel requirements, we can't discuss all in one breath. I was referring to Bergerie1. His RTOW calculation at Nairobi was incorrect. Period! Refusing some payload or passengers is always a bad idea but you have to do it many times otherwise Regulated Takeoff Weight will become a joke. You have no option unless you manipulate the BO. I do not want to repeat what I have already stated. I don't know how any one can justify doing unplanned low flying with passengers and a VIP/Semi VIP on board and claim a pat on the back.You can check weather and traffic but ask Sully he will tell you cannot check for birds. Then you burn fuel and along with it your diversion and claim privileges of a committed landing. And despite my quoting Airbus manual page number B737900er states EASA doesn't have landing weight limit. May be AIRBUS doesn't form part of EASA.
With my previous example of last minute load, can you say at what moment the RTOW has been violated?
Thank you for answering.

vilas
9th May 2018, 18:30
As long as the load sheet shows all weights below or equal to limit weights it's fine. As I have been pointing out some people relate RTOW only to takeoff. That's not so, even landing and GA performance at destination has influece on takeoff weight.

new_era
10th May 2018, 02:06
No! You can't. Arithmetically possible but not legally. (...) You cannot legally exceed that and then burn extra to get within MLW.
Ok! So a least everything is clear regarding this and no one plans to "cheat"
As for RTOW, if it is the equivalent of limitation due to other than structural with Boeing, you do not have to calculate anything. It specified in the OM-C (sometimes lower with wet runway) and it is the MLW you have to consider for the flight instead of the structural mlw.

bar none
10th May 2018, 10:12
Just to complicate things even further Tristars used to have a variable zero fuel weight.

InSoMnIaC
10th May 2018, 10:56
Every aircraft has a variable zero fuel weight

vilas
10th May 2018, 12:05
Every aircraft has a variable zero fuel weight A particular aircraft has only one ZFW. It is not variable but there can be some versions of the same model with different certified ZFW.

vilas
10th May 2018, 12:26
and it is the MLW you have to consider for the flight instead of the structural mlw. I am unable to understand the meaning of this statement. What's the difference between MLW and structural mlw?

Goldenrivett
10th May 2018, 12:54
vilas,
What's the difference between MLW and structural mlw?
Some aircraft are restricted to a Maximum Planned Landing Weight at certain airfields due to performance.
e.g. B707 at old Heraklion airport in 70s was restricted to Structural MLW minus 2 Tons.

AerocatS2A
10th May 2018, 13:02
A particular aircraft has only one ZFW. It is not variable but there can be some versions of the same model with different certified ZFW.
A particular aircraft has one MAX ZFW but the actual ZFW is different on each flight. In that sense all aircraft have a variable ZFW.

AerocatS2A
10th May 2018, 13:05
I am unable to understand the meaning of this statement. What's the difference between MLW and structural mlw?
MLW takes into account the length of runway, density altitude, runway slope, braking action, go-around performance etc. it canít be more than structural but may well be less.

InSoMnIaC
10th May 2018, 13:42
A particular aircraft has only one ZFW. It is not variable but there can be some versions of the same model with different certified ZFW.


I know. I fly once such aircraft. My comment was tongue in cheek.. he didnt say variable Maximum ZFW :)

MarkerInbound
10th May 2018, 15:29
Some Boeings do have a variable ZFW. There will be a number such as 276,691 kg for the ZFW. However you can operate that aircraft up to a ZFW 288,031 kg as long as there is a reduction in the MTOW. The W&B manual will have a chart showing the trade off between higher ZFW and lower MTOW.

bar none
10th May 2018, 16:13
Further to my post no 56 I meant Tristars used to have a variable MAX zero fuel weight. British Airtours was the airline.

vilas
10th May 2018, 17:10
MLW takes into account the length of runway, density altitude, runway slope, braking action, go-around performance etc. it canít be more than structural but may well be less. why not just call it landing weight? Max landing weight is a limitation that is structural. When you calculate the RTOW for that take off weight a certain landing weight results. We don't calculate max landing weight.

AerocatS2A
10th May 2018, 22:46
why not just call it landing weight? Max landing weight is a limitation that is structural. When you calculate the RTOW for that take off weight a certain landing weight results. We don't calculate max landing weight.
Because it’s not the landing weight. The landing weight is the actual landing weight. The max landing weight is the max weight you could land at on the day, might be limited by structural limit or some lower limit due to a short runway.

new_era
11th May 2018, 00:01
why not just call it landing weight? Max landing weight is a limitation that is structural. When you calculate the RTOW for that take off weight a certain landing weight results. We don't calculate max landing weight.
There are 2 types of limitation: structural and performance.
Structural is about your aircraft and it is normally fix number (c.f FCOM)
Performance is about other than aircraft (rwy length/condition, obstacle, etc..) and it is variable (c.f Company Manual Route OM-C)
You chose the most restrictive applicable for your flight. Usually it is structural.

vilas
13th May 2018, 09:11
pineteam
I agree with Goldenrivett on this one. We discussed about it recently in this thread: https://www.pprune.org/questions/607...imum-fuel.html (https://www.pprune.org/!607266!https://www.pprune.org/questions/607266-flying-b-minimum-fuel.html) What you discussed in that thread had many riders and a lot of confusion. Imagine you are flying a commercial jet from A to B, flight time is 1h15m, A is your also your destination alternate and both airports are single runway only and weather is cavok on both airports.
Due to long taxi on the ground, you have burned more fuel than expected and once airbone you only have 5 min extra fuel Since you mentioned an alternate, it is an IFR flight plan with alternate required. Then it requires usual fuel A to B+Cont+ to C+30min hold. You couldn't burn that during taxiing. There is an exception of not requiring a destination alternate in IFR but it has two conditions i.e. VMC approach and landing is possible and the destination has two runways. Since your destination has only one runway you cannot file an IFR flight plan. So I take it as a VFR flight plan which requires fuel A to B + 30min . If you discover after take off that you have only 5min extra then you simply land back. You would avoid everything that can happen at destination. Five minutes fuel is nothing by the time you reach there you may not have even that. Now coming to our thread, a President of a country should definitely be treated as more valuable than half a ton of vegetables. For heaven's sake you can't take law in your hand and do whatever you feel like.

Goldenrivett
13th May 2018, 10:35
vilas,
If you discover after take off that you have only 5min extra then you simply land back. You would avoid everything that can happen at destination. Five minutes fuel is nothing by the time you reach there you may not have even that.
OK, please see thread # 37.
Consider 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?

A) 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.
B) 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 would you take, A or B?

vilas
13th May 2018, 12:44
Goldenrivette
Before I answer your question, in support of my post I will quote from IFALPA(ICAO) document you referred.
4.3.7.2 The pilot-in-command shall continually ensure that the amount of usable fuel remaining on board is not less than the fuel required to proceed to an aerodrome where a safe landing can be made with the planned final reserve fuel remaining upon landing.
So the moment you discover you only have 5minutes reserve instead of 30min you have to land back otherwise you violate this. What happens at destination won't save you. On takeoff you are supposed to be go minded and not in the air. Now coming to your question. Do a FORDEC and see for yourself. With further delay which cuts into alt+reserve regulation wise you should divert. Because if you are delayed still further or forced to divert later due to unforeseen events then you will land much short of regulatory minimum.

AerocatS2A
13th May 2018, 13:18
Vilas, your quote only mentions final reserve, not alternate plus reserve. I don’t fly in your regulatory environment, but that quote itself doesn’t support what you are saying. Ditto for a mayday call, it’s a fuel mayday when you will land with less than fixed reserve, not when you will land with less than alternate plus reserve. Surely you can see that it is far safer to land at a good destination with lots of fuel instead of an alternate with minimum fuel. Why would you divert from a perfectly good airfield?

new_era
13th May 2018, 13:38
You are Mayday Fuel if you expect to land at the nearest suitable airport with less than the final reserve (30 mn for jet). Example: your fob is 1h and you need 35 mn to fly to the nearest suitable airport.

You are Minimum Fuel if "committed to land at an airport" (alternate, destination or whatever) meaning you go to that airport and you expect to land at that airport with a fuel not less than the Final Reserve BUT you cannot accept any delay otherwise you would land with less than final reserve.

vilas
13th May 2018, 14:17
The quote is about post #69 which is in reply to another thread by pineteam where in a VFR flight plan there is no alternate fuel all you have is 30min extra. The rest deals with Golden's example which I agree I misquoted. In his case the situation will only arrive at the alternate if you divert later. I will correct my post. What is practical and what is regulatory sometimes does not tally and in dynamic environments things can rapidly change. Off course this example is hypothetical. The decision will also depend on what is your sequence in landing.

vilas
13th May 2018, 14:21
new_era
I corrected my post. I was dealing with two different scenarios caused the confusion.

Goldenrivett
13th May 2018, 14:57
vilas,
With further delay which cuts into alt+reserve regulation wise you should divert.
Interesting logic.
Q. Do you believe the act of diverting will guarantee there will be no "unforeseen events" at your diversion airfield?

What is practical and what is regulatory sometimes does not tally
I have found all regulations are logical and practical. Please give an example of one which is not.

vilas
13th May 2018, 16:33
Example? The whole thread is about that. RTOW Ldg Wt Ltd? Practical is carry extra and burn it before landing but not allowed to do so unless you manipulate the BO. Why? Practical is to carry minimum fuel and burn alternate if you find weather OK and land. Not allowed legally. Believe me DGCA checks fuel in tanks airlines/pilots have been penalized. Why aviation while driving at red light see the traffic and jump. Not allowed.

Goldenrivett
13th May 2018, 21:02
vilas,
Practical is carry extra and burn it before landing but not allowed to do so unless you manipulate the BO.
You may load extra fuel up to your Take Off limited RTOW.
You have to consume surplus fuel (e.g. by holding) to ensure you are below maximum landing weight. Hence adjust the planned burn for the load sheet calculation.

Practical is to carry minimum fuel and burn alternate if you find weather OK and land. Not allowed legally.
When operating to an isolated airfield (say Seychelles), inflight fuel management allows use of decision point.
"Decision Point: The nominated point, or points, en-route beyond which a flight can proceed provided defined operational requirements, including fuel, are met. If these requirements cannot be met the flight will proceed to a nominated Alternate Aerodrome.
Note 1: The operational requirements required to be met are specified by the operator and approved, if required, by the State.
Note 2: Once past the final Decision Point the flight may not have the ability to divert and may be committed to a landing at the destination aerodrome."

Bergerie 1, in his VC10, may have elected to make his decision point say 10,000 ft on the descent. Weather at destination was CAVOK, he was number one for the approach and thus a successful landing was assured. If he decided Landing was not assured, then he could easily have diverted to Mombassa with all Reserves intact.
He was overweight for a straight in approach, so elected to "hold" by doing a visual circuit around the Island and landed below Max Landing weight at his destination.

Which bits are "Not allowed legally"?

Weeonerotate
13th May 2018, 23:20
pineteam
What you discussed in that thread had many riders and a lot of confusion.


It seems pretty clear to me, except I do not understand so many pilots are so eager for extra fuel.


Since you mentioned an alternate, it is an IFR flight plan with alternate required. Then it requires usual fuel A to B+Cont+ to C+30min hold. You couldn't burn that during taxiing. There is an exception of not requiring a destination alternate in IFR but it has two conditions i.e. VMC approach and landing is possible and the destination has two runways. Since your destination has only one runway you cannot file an IFR flight plan. So I take it as a VFR flight plan which requires fuel A to B + 30min . If you discover after take off that you have only 5min extra then you simply land back. You would avoid everything that can happen at destination. Five minutes fuel is nothing by the time you reach there you may not have even that. Now coming to our thread, a President of a country should definitely be treated as more valuable than half a ton of vegetables. For heaven's sake you can't take law in your hand and do whatever you feel like.

You have so many wrongs here, and in most of your replies. You seriously need to read up on this, not joking.

The fuel in your PLANNING phase needs to be in your tanks at pushback, this is taxi,trip,cont,alt,+final.

You can do a continues inflight replanning, just always land with final reserves. Where you land does not matter.

If you return to departure airport because you are 5 min short, I hope the DFO will call you in for tea no biscuits. If you divert on a cavok day because you are down to final+alt, youíll get another invite for tea!

All these rules are pretty simple, and been the same in all the different CAAs I have worked under, its simple and straightforward, so donít make it complicated.

happy landings.. also on final fuel.

vilas
14th May 2018, 06:21
Goldenrivette
We are going round in circles. I hope you get the facts right. You can disagree if I express an opinion but not with the regulations
You may load extra fuel up to your Take Off limited RTOW.
You have to consume surplus fuel (e.g. by holding) to ensure you are below maximum landing weight. Hence adjust the planned burn for the load sheet calculation. Read my post #24 and #38. You are an airbus pilot read page 74 of PTM. RTOW also contains Ldg Wt Ltd takeoff weight. So you cannot load more than that. You are doing manipulation with BO not for load sheet calculation but to stay within the legal Ldg. Wt. limited RTOW.
Bergerie1 filed Mombasa as an alternate so it was not isolated airfield case and all your explanation for isolated airfield is irrelevant and not valid.
Which bits are "Not allowed legally"? virtually everything. Lifting Pay load and raising ZFW which put RTOW beyond limit ( read post #38). Burning alternate fuel. Doing unplanned low flying at 500ft with passengers and if I may say a VIP on board. If slammed with sea gulls I can assure you, he wouldn't have got Sully's welcome. And Seychelles has or had only one runway. If this is common sense then I am happy I don't have that. Actually I should ask what is legal in this flight?

Goldenrivett
14th May 2018, 07:44
vilas,
Actually I should ask what is legal in this flight?

In an earlier post, I thought you said you'd flow B707. How on earth did you operate that into places like BDA or SEY without using Decision Point Planning?
See http://www.ifalpa.org/store/doc9976.pdf .
Look at page 152 Figure 5-App, 3-1:

If you are not familiar with DP Planning, then stop accusing Bergerie 1 of doing something illegal in the 1970s.

vilas
14th May 2018, 09:12
DP planning is not atomic science and whatever you are capable of understanding why wouldn't I understand? Your perception of procedures and regulations is different. Haven't we seen that before? I have nothing more on the subject.