MZFW now considered in loading calculations

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Chris Trott
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MZFW now considered in loading calculations

Post by Chris Trott »

Gentlemen,

Konny has finally been able to return to active development of FlyNET and he has already graced us with a new feature to FlyNET - MZFW consideration.

The calculation has been simplified somewhat over real life considerations, but it will greatly enhance the realism and difficulty of the system. The calculation goes like this (directly quoting Konny) -
1. Calculate number of passengers
2. Take the maximum cargo value and deduct the baggage ( PAX x 25kg )
3. If the new maximum cargo value is higher than "MZFW - DOW - PAX x (25kg + 77kg)", adjust the maximum cargo value
4. Calculate cargo
As a result, I ask that all of the CBFS Managers check the CBFS fleet aircraft types in the database and make sure that *ALL* fields are properly filled out on the aircraft. If MZFW cannot be found, find the MLW (Maximum Landing Weight) and deduct 20%. This seems to be a good number to give a proper fuel reserve for the aircraft without eliminating their cargo carrying capacity. If someone finds a better reduction number to use, please let me know ASAP and I'll revise the guidelines on the FlyNET Forum and let the other staff members know.

Also, for the lighter aircraft like the Chippie, if it doesn't have an MZFW right now, just set the MZFW=MTOW. Since these aircraft aren't used to make money, they're only loaded with a couple of pax and cargo, and those numbers shouldn't be greater than what is available to have nearly full tanks anyway, so MZFW isn't a major consideration but it does still need to be entered.

Thanks for your attention to this matter!

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Post by DaveB »

TksVM for this Chris :wink:

At what point in the proceedings is this calculation going to take place?? I'd presume FlyNET will check after fuel has been loaded otherwise some aircraft are not going to make it to their destination :shock: There should be little or no impact on certain aircraft.. the 146's spring to mind as they were designed with a MTOW to equal full pax/cargo and fuel.

I need to see it in action I think :wink:

ATB

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Chris Trott
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Post by Chris Trott »

This is calculated when you book the flight. MZFW has no bearing on fuel weight. MZFW is the maximum weight allowable for the aircraft WITHOUT fuel (hence- Maximum Zero Fuel Weight). :smile:

The point being, that if any of the CBFS Aircraft Types are missing the MZFW or it is incorrect, it needs to be added because failure to do so will result in no cargo being loaded for the flight.

The point of the MZFW is that it ensures that the aircraft is not loaded above a point where a safe flight cannot be completed. What therefore is the point of having an aircraft where MZFW = MTOW since that means that if the plane is fully loaded it can't carry any fuel and thus has no practical purpose?

I can assure you that the MZFW of the BAe-146 is at least several thousand pounds below MTOW. It's MLW (Maximum Landing Weight) may be the same as the MTOW, but the MZFW is always going to be less that MTOW. The only aircraft without an MZFW are light aircraft where it's not required as part of the certification process. I know that the Cessna 206, if certified for commercial operations *DOES* have a MZFW, but if you look at the POH, none is stated. It's stated in the Aircraft Operations Manual that is only in place on commercial certified aircraft (as there are several additional modifications that have to take place to certify a Cessna 206 for commercial operations).

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Post by MALTBY D »

Thanks Chris

Our BAC 1-11 & Trident numbers seem ok on FlyNet, except for the cargo capacity.

I'm not sure what it ought to be, but they do look odd at the moment...
1-11 200 = 4360 kg
1-11 400 = 3158 kg
1-11 500 = 1484 kg
Tri 2 = 12700 kg
Tri 3 = 12700 kg

I've no idea where these came from originally & clearly they are bollox.

Can we just set this cargo capacity value as the max payload?
ie. if they carried no passengers you could load up the hold to the max payload weight.

Taking a 1-11 500 for example...
MZFW - DOW - PAX x (25kg + 77kg)
36741 - 24758 - (109 x (25 + 77)) = 865
So with 109 pax it could actually take 865 kg cargo.

I'm not sure I understand it right.
Any opinions?

DM
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Chris Trott
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Post by Chris Trott »

Yep, you're correct in your understanding.

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Post by DaveB »

Hi CT..

Yup.. I know what MZFW is and my ref to the 146 was for the real aircraft.. not the cr@p some of us fly very occassionally on the VA :wink:

DM intimated possible problems with the 1-11 and Tridents and as far as I can remember, the Vanguard has a similar problem.. not so much with it's MZFW but with it's cargo capacity on the pax aircraft.. Flynet presumes max pax and max cargo which in practice, would make it over MTOW. The default DC3 suffers the same btw :wink: It could be that this latest addition by Konny will sort this anomaly out without any input from us :smile: I can't recall any data input for our aircraft being knowingly incorrect though it is sometimes the case that not all the info was available. :smile:

ATB

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Post by RAF_Quantum »

Hi all,

Chris,

The weights for the Britannias were a load of cack, not submitted by CBFS. I've sent an edit with revised figures per 'Bristol-Britannia.com' and a MZFW provided by Fraser. The cargo can be left as-is as there is a bit to spare after pax and baggage before we get to MZFW.

DaveB,

The cash cow status of some of the aircraft will be gone, but we knew that anyway. The Vanguard is one of the few passenger aircraft that had the weight carrying capacity within it's baggage holds to bring it to MZFW. A lot of the older aircraft would only be able to carry the heavier loads if seats were removed and baggage holds were very much baggage only holds. A lot of the figures were questionable but this will sort most of them out now.

Rgds

John
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Chris Trott
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Post by Chris Trott »

That is correct. It wasn't until the late 1970s and early 1980s where the carriage of cargo by passenger aircraft really became a reality. Mostly this was due to the advent of high-efficiency, high-bypass turbofan engines that allowed for much larger interior volumes and true widebody aircraft like the DC-10, L1011, 747, and A300 where the lower deck volume was large enough for palletized cargo to be quickly loaded and unloaded from the aircraft. What before required an upper deck hold (i.e. Combis) or dedicated freighter to be flown, could now be fitted into the lower holds of these new aircraft. Now the maximum cargo capacity of the aircraft could become much greater and in fact, some aircraft could be loaded to MZFW by cargo alone (the DC-10-10 comes to mind), allowing the aircraft to potentially make a profit even when flying without passengers. The old calculation method loaded everything to 100% if the airline's reputation was high enough, regardless of MZFW, making it possible for modern aircraft with accurate loading information to make massive profits since they had massive cargo capacity that in reality usually isn't realized. The new MZFW calculation allows for the passengers and baggage to be maximized and the cargo load to fill any remaining space up to the aircraft's MZFW, meaning that on most flights, the pilot can load the appropriate amount of fuel and not reach MTOW, thus it makes the operations more reasonable and levels the playing field on the older aircraft that don't have the ability to carry those massive amounts of cargo since now the cargo will only fill to MZFW instead of MTOW.

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Post by DaveB »

Tks Chris (and John) :wink:

That makes complete sense and I for one look forward to profit margins on certain aircraft being more inline with the norm :wink:

ATB

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Post by DispatchDragon »

Gents

ALL the 1-11s have the correct MZFW per the 1-11 website
Other than that nothing has been changed - The odd 'cargo" weights
that DM refers to are a mystery - I didnt change them and I know no one
from CBFS did - and they should make NO difference to the equation anyway - The way it works in real life - if the BOW and payload exceed
MZFW your screwed no matter what - people bags or cargo are coming off
the only fuel that can enter the equation is ballast (read unusable fuel). What flynet should be doing is this

Taking the BOW of the aircraft .
Loading the pax/bags as posted by flyswat
THEN loading cargo up to MZFW (this should be an option)
Then load fuel - If payload and sector fuel exceeds MTOW
then your only option is start offloading cargo then pax until you reach
MTOW.

BTW Chris - I suggest that you all placate Konny to hard wire the structural weights of the aircraft into Flynet do stop some of the tampering that goes on - If you look at the figures I posted for the 777 and the A340 at flynet you will see that some of the VAs are grossly overflying the
aircrafts capabilities.


Leif

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