Flight Planning Software

[reprise]

Hey guys,

I'm working on a flight plan Excel sheet, and I'm not really well versed in excel formulae and this one has kind of stumped me.

I'm creating a new cell on our airline's operational flight plan form, and my job is to display the current weight and balance index for the particular aircraft which has been selected. All the indices are different and all the indices depend on the current weight and moment-arm of the aircraft, but both those numbers are always current on a seperate sheet of the spreadsheet.

I thought I could probably figure out how to do it but I've gotten fed up so I thought I would ask for help, and if you fine folks can understand these formulae and programming magics I would be eternally grateful.. I understand that to reference a different cell on a different sheet you use something like Sheet2!C4 but it's more complicated than that, the cell reference depends on what aircraft a person selects in a dropdown box on the top of the screen. Which cell you want to reference is always different and that's what I don't understand how to make that conditional reference.

So here's the problem I can't figure out -- How do you reference a different cell on a seperate sheet depending on what selection a person makes on a dropdown box on sheet2 of the spreadsheet?

I know it's possible, I've seen the same thing done where a reference weight comes up in a different cell on sheet2 depending on what selection a person makes for airplanes on sheet2 -- but I don't know how to do it... here is the formula that guy used:

=IF($P$2="","",IF(M13="","",IF(E5="","",IF(E5="multiple",AH11,INDEX(type_data,MATCH($E$5,registration,0),3)))))

So if you guys can understand that formula and apply it to my issue that'd be awesome. Dunno how to figure it out. I have the spreadsheet on my computer though, and I gotta figure out how to do this new function, which is basically the same function as that above formula.

Thanks for your consideration!

EDIT

Actually I may as well tell you -- what I want is ((OMA - 227.5) x OW) / 6000) - 0.6

Where,

OMA = operating moment arm on sheet5
OW = operating weight on sheet5

And there are 5 different OMA's and OW's on sheet5 depending on what selection you make on sheet2