Not sure if this is the right catagory for this post but here it goes. I am a private pilot based in the NE and have been flying PMDG's md11 and js41 for quite a while and are just incredible. I've used both a/c's supplied weight and balance software and given loadsheet and was wondering, more for the md, how variable items such as potable water and the catered food are factored into the weight and balance? are they just added as a seperate zone similar to the passengers' weights? thanks

Hi Nameless,Are you thinking real world...or in the PMDG simulation?Thanks,Chris.

Both would be great. In the real world, I've seen the FA's do a head count in each zone and hand a sheet to the pilots and I'm guessing there's a section for the catered stuff but that's just a guess. But no clue in PMDG's. maybe just factored into the ZFW?David A.

I work in the weight and balance department for a RW airline that only operates NG's and I can say that potable water and catered food are calculated in the OEW. They are variable weights but for the most part the potable water is topped up before every flight as well as any galley items. The flight also is initialy planned with a weight buffer from dispatch to allow any variance in weight to a certain limit. In the case the potable water wasnt filled up or galley items added, there isnt enough weight variance to be of concern. We also do have the ability to change a few things on our end. Such as added life rafts for ETOPS flights or less flight attendants, ect. when everything is said and done with baggage,cargo, passangers, and fuel the captain receives a trim report that accurately reflects the weight on board the aircraft.Greg Keath

I work as a dispatcher - part of my job is the preparation of the loadsheet.When we calculate the Zero Fuel Weight - it is made of two parts - Dry Operating Weight + PayloadPayload= Passengers + their hand luggage + checked bags + cargo/mail + anything loaded specifically for revenue or some other reason (for example company documents or something along those lines)Dry Operating Weight = Operational Empty Weight + Weight of the crew + Weight of the cateringOEW = This is "fixed" and includes the plane when it's empty, all the documentation on board, all the things needed to make it legal - first aid kits, loud hailers etc etc....and included potable water and assumes the waste tank is empty.Weight of the crew - depends on the "crew config" - and depends on the type of flight being performed. "Crew config" is often passed as x over y so "We're 2 over 2 today". Two Flight deck members and 2 cabin attendants. This varies quite alot depending on whether the crew are training or if the flight is particularly long.As a dispatcher I then consult a table - which tells me the weight and index affect of the crew config - and I add this to the OEW.The weight of the catering is, in my experience fixed for the most part, but changes depending on the type of flight - in my last job we had two catering codes - one for charters (where everyone gets fed) and one for scheduled services (where it's buy on board). In my current job there are several codes - one where the aircraft is catered at the outstation, and comes in to us - so we apply "one way catering". This includes all the food, and the equipment involved too.Again - this is looked up on a table - and added to the OEW.It should be noted - that the plane is weighed once .... and this establishes the OEW - and this never reflects the weight of the plane again. We then assume weights of the crew members ... and for the catering...and then use average weights for bags, passengers and hand luggage....This means alot of what we do is essentially guesstimation...but I believe the Canadian authories especially have investigated how close to "reality" this is - and it bears rather a close resembelence - simply a case of all the errors balancing out - and putting us slap bang on the actual weight.David,What you have seen with the count - is the flight attendant informing the captain where everyone is sat - he then compares this with the loadsheet - so he then can set the trim to a value that reflects the actual Center of Gravity - there have been a couple of 737NG incidents where the loadsheet incorrectly reflected the seats allocated - and the aircraft tipped onto it's tail when takeoff thrust was set.Hope this helps....In terms of the PMDG simulation - in fact every addon i've seen - models a single Dry Operating Weight - so one crew config, one catering code and one OEW. Doubt PMDG have something in line for upcoming products...but who knows - they're implimenting alot of Flight Sim "firsts" so maybe....Chris.

Both would be great. In the real world, I've seen the FA's do a head count in each zone and hand a sheet to the pilots and I'm guessing there's a section for the catered stuff but that's just a guess. But no clue in PMDG's. maybe just factored into the ZFW?David A.

I can confirm this needs to be done on occasion, and depending on the aviation laws in the country the airline is based, they often are counting number of males, females and children in each zone as those also are calculated as seperate weights.

Thanks for the replys. It's great to be able to connect to pros like you guys, very humbling as a private pilot SEL.

Thanks for the replys. It's great to be able to connect to pros like you guys, very humbling as a private pilot SEL.

No problem, I owe alot to this community for giving me such a strong passion for aviation as both a hobby and and in the workplace.