WEIGHT AND
BALANCE
AIRPLANE
OPERATIONS
MANUAL
1-06-40
Page
16
Code
03
REVISION 29
EXAMPLE 2 (EMB-145 MODEL LR):
For the EMB-145LR on a standard configuration (50 seats) with the
passenger cabin divided in three sections.
Section A refers to rows 1 to 6, section B refers to rows 7 to 12 and
section C refers to rows 13 to 18.
Considering the window and aisle seating concept, the first seat to be
occupied is window-row 1, then window-row 2, then windows-row 3,
then windows-row 4, ..., then windows-row 18, then aisle-row 3, then
aisle-row 4, ..., then aisle-row 18.
When window-row 1 is occupied, there is a moment margin of the
passenger weight times the distance between cabin A centroid and row
1 centroid. When window-row 2 is occupied, the moment margin is
increased by the passenger weight times the distance between cabin A
centroid and row 2 centroid. The moment margin keeps increasing
until the seats aft of the cabin centroid start being filled and then
moment margin decreases.
When cabin B starts being filled, the moment margin starts increasing
again and then decreases when the seats aft of cabin B centroid are
filled. The same occurs with cabin C.
The forward seating allowance to be used in the determination of the
constrained CG envelope is the summation of the most negative
moment change of each cabin section.
For the aft seating allowance, a very similar procedure is performed,
but considering the aircraft being loaded from the aft portion of the
cabin, and considering the most positive moment change of each
cabin section.
The following tables show the determination of the forward and aft
seating allowances:
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