I'm going through this stuff now and I'm stuck on Charlie. If anyone has the ATC BAK book, it'll allow you to follow along with my confusion easier, hopefully.
Ok, for those playing along at home, page 329 is the question "Load System Charlie - Working".
Basically, it's given me all the info except the load in Row 2. The question it asks is, what is the maximum passenger weight, in kg, that may be carried in row 2 at take off?
The current data, with 0 at row 2 is:
ZFW = 75kg, Arm: 2,927mm, Index units: 25,790
Fuel = 99kg, Arm: 2,950, IU: 2920
TOW = 980kg, Arm: 2,930, IU: 28,710
And they've given a "Ballast to add" formula:
[GW (kg) x distance to move CG (mm)] / [new STA - current STA]
GW = 980
Distance to move = AFT limit - current STA = 3,004 - 2,930 = 74mm
New STA = 3600
Current STA = 2930
Therefore ballast to add = 108 kg = max passenger weight in row 2.
My question is....how did they arrive at the new STA value?
I can't seem to work it out... :confused: