Hope this helps
 

MZFW - Maximum weight allowed before usable fuel and
other specified usable agents must be loaded in defined sections of the aircraft as limited by strength
and airworthiness requirements.

MTW - Maximum weight for ground taxi as limited by aircraft
strength and airworthiness requirements. (It includes weight of taxi and start-up fuel.)

MTOW - Maximum weight for takeoff as limited by aircraft
strength and airworthiness requirements. (This is the maximum weight at start of the takeoff run.)

In other words, the Max Take-Off Weight is the Max Taxi Weight minus the taxi fuel.

Cheers :cool:

MTW
 

mmm! - quite correct.

But taxi fuel can be higher to give a higher than specified MTOW. and LDW, strictly Freight Dog calculation in Africa.

EZFW weight can be used for planning purposes until the AZFW is known.

:cool:

For the attention of itsinthebox

Your question another question about the ZFW / ZFM debate, why plot it on the trim chart?

It is a reference for the PIC to enter into the FMC and for the calculation of the Vr speeds. The loadsheet is a legal document and has to be anotated and signed correct by the loadmaster/dispatcher and the Captain.

Hope this helps
:D

Aux belly tanks
 

I don't think this issue has been addressed:

When aux tankage is installed in the hold, shouldn't any fuel in these be counted in ZFW just as if it were cargo?

It's being carried by the spar exactly as if it were cargo.

=============================================
I don't think this issue has been addressed:

When aux tankage is installed in the hold, shouldn't any fuel in these be counted in ZFW just as if it were cargo?

It's being carried by the spar exactly as if it were cargo
=============================================
Centre Tank Fuel either trapped, becuase of some defect in the
Fuel System, or when using Centre Tank Fuel as a Trim/Ballast for an empty sector, will count as load and therefore will be included as part of ZFW.

DIH

To think that I've worked with aircraft having a VARIABLE MZFW (B744, a fuel density thing), or NO MZFW AT ALL (DHC6 Twin Otter, a struts thing).

MZFW of course represents a manufacturer-defined limitation designed to prevent wing-fuselage joint over-stressing while operating the aircraft at maximum allowable loadfactor and at MTOW (structural), and is expressed in a (fuselage) weight limit.
The derived/designed MZFW represents a theoretical condition, and has no doubt resulted from a necessity to prevent mishandling.

Unless specifically stated otherwise in the Flight Manual, aircraft equipped with a CWT have defined/designed MZFW's that take a full CWT on departure into consideration. Contrary to ballast fuel, useable CWT fuel is therefor not part of any ZFW considerations.
Scavenge pumps INOP will cause a portion of CWT fuel to be un-useable, and therefor become ballast, however, no ZFW impact.

Non-standard fuselage AUX tanks (as in A319CJ), although representing useable fuel, should be considered to impact a ZFW.
The published MZFW should be lowered with the fuel mass loaded into these tanks when the MZFW of the original aircraft design/certification does not take fuselage AUX tank fuel into consideration, resulting in a lower max payload (pardon the pun).

... 4 pages of blissfull ignorance, blatant misconceptions, goodhearted explanations, and a lot of air- which includes this post, of course...

Cheers, Max. :ok:

Nice post Max..............What's a CWT mate?

FEBA, good day,

CWT = Center Wing Tank.

Cheers- Max :ok:

Worrying state of Dispatch/Loading in UK
 

If you think these postings indicate a worrying state of affairs in UK try asking a few questions of your dispatcher/loader around the international traps.

Now that will give you cause for worry!

See Tech log forum Weight & Balance enhancements.

Chok Dee

zfw
 

As an instructor of many years, I can clearly state that agents are taught that the reason for having a ZFW is to ensure that
a/The structure on the wing roots is not compromised/stressed beyond its capability if ZFW was at maximum permitted
b/At any stage of a flight, the captain uses the ZFW to determine diversion data in case of landing at unscheduled airports, usually just into flight. (ZFW plus fuel remaining = est landing weight.
.
There have been two instances whereby an aircraft has run out of fuel en route and still glided safely into land.
(Alidair Viscount-Exeter,, Air Transat-Azores.
................
Any employer using despatchers as runners for the summer season or periodically should not let them lose onto a/c until they have proven training records of understanding _theory of flight-ZFW/TOW/RLW/Loadsheet principals and 6 point check of any document handed to them to give to crew.
........
There is no legislation as to training capabilities in law yet but any good crew member may ask to see training records of any despatcher who appears to be unknowledgeable about the loadsheet/loading instructions.
.......
Who knows..It could just stop a potential incident if more challenges were made to the ground services handling agent about competency of the staff let loose to visit the flight deck!!

Sorry if I haven't read through it all yet, but has anyone added the extra spanner in the works of carrying wing relieving fuel in order to get more out of the ZFW?

Doc C

I have asked a number of people from Engineers to Pilots. Most people are unaware. Please spill the beans......... :p

My sanity (and others ) depend upon it......:)

Craggs

Ballast Fuel
 

On the Citation3, and perhaps others up the line there was unusable fuel, in the tanks, that was considered as ballast fuel.
Long time ago but its in the back of my mind....

Bumz

LOL...okay..all this discussion is very interesting. So here I go. This is what I learn after being a Loadsheeter/Loadmaster/Flight Dispatcher.

DOW = Dry Operating Weight (Weight of the Aircraft/Crew/Pantry..etc..etc..But this depends also on the airlines requirement what they consider as DOW.)

+ cargo + pax + baggage + ULD's (some airlines use this as part of DOW)

ZFW = Zero Fuel Weight. (+ Block Fuel / RAMP Fuel)

= RAMP Weight (- Taxi Fuel)

= Takeoff Weight (TOW) (- Trip Fuel)

= Landing Weight (LDW)

MZFW = Maximum Zero Fuel Weight. The structural limit of the aircraft can handle.

Variable ZFW = This is usually meant for freighter aircraft like B742 or B744. What it does is basically allow the aircraft to carry more weight than the MZFW but the MTOW is greatly reduced.

MTXW = Maximum Taxi Weight

MTOW = Maximum Takeoff Weight

RTOW = Regulated/Restricted Takeoff Weight (if there is a restriction the TOW cannot exceed this weight)

MLDW = Maximum Landing Weight.

All these weights calculated in the 'loadsheet' cannot exceed these figures at any given point.

As for why plot it in the trim chart, well its to see if the weights and the position of cargo/baggage/passenger loaded in the aircraft actually 'balance' the aircraft out. As aircraft has 'curve' each weights has its own limitation hence its to ensure that both weights and the 'balance' of the aircraft is in the safety limits. Like freighter aircraft, the trim checks is to prevent 'tail-tipping' of the aircraft itself. Also, the pilots can use it for FMC for the whole flight.
:mad: