C. BALANCE CHART DESIGN
b) Inaccuracy on the cargo weight
Cargo weight is supposed to be known without inaccuracy : for freight loading airlines usually
weight the pallets and container after they are prepared, then for baggage the total weight of
baggage per flight is accurately known as each individual piece of luggage is weighed.
So Ecargo weight is usually supposed to be nil.
Note : in case the cargo weight cannot be accurately known it may be needed to introduce a cargo weight inaccuracy, this inaccuracy may be due to the fact that the ULD weight is estimated and not weighed or to the fact that the baggage weight per cargo position is estimated, usually using an average weight per baggage piece. In the case a cargo weight inaccuracy is to be determined the method to be applied is similar to the one described in the next chapter for passenger weight inaccuracy.
3.4.2. Inaccuracy on passenger loading on board the aircraft
a) Inaccuracy on the passengers’ location
On the balance chart the passenger influence is taken into account as a delta index per passenger cabin section (CABIN OA, CABIN OB, …), this delta index is based on an average H-arm for the corresponding cabin section. Now the real loading may result in an H-arm different from the average one. This difference will generate an inaccuracy on the aircraft CG determination. This inaccuracy is named passenger distribution inaccuracy.
. Passenger distribution inaccuracy:
Eitem location = Witem x (H-armitem real . H-armitem assumed)
Eitem location is determined with H-armitem assumed being H-armCabinOX and H-armitem real being the H-arm of the real passengers seating configuration.
The process for checking the different configuration is the following :
. Determine the cabin section average H-arm : refer to paragraph 2.4 .Index for
passenger boarding.
. Determine the passenger seating configuration which generates a significant inaccuracy.
The maximum inaccuracy would be determined when all seats in front of the average H-arm are full and all seats aft of the average H-arm are empty. But this boarding configuration is not a realistic one and the inaccuracy is in this case very high. So a realistic boarding scenario needs to be determined.
WEIGHT AND
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WEIGHT AND
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C. BALANCE CHART DESIGN
The following boarding scenario is taken into account : . Passengers board first on (or ask first for) window seats. . Passengers board then on aisle seats . Finally passengers board on middle seats.
Following this scenario the forward inaccuracy is determined when . Either all the window seats in front of the average H-arm are full and all the window seats aft of the average H-arm are empty.
H-arm real passenger
. Or all window seats are full and all the aisle seats in front of the average H-arm are full and all the aisle seats aft of the average H-arm are empty. 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：Getting to Grips with Aircraft Weight and Balance(68)
