Whoo boy... I probably don't need to say I am an Excel novice! :)

I can pick my way through the program with general ease, but this new
idea I conjured up seems beyond my skill level. Moreover, I don't
know enough of the phraseology to find aid in my help searches.

Please bear with me, and I will set up the issue:

I have a multiple-sheet document started. The sheets share some data
between them and transpose it all onto one "master" sheet, as I call
it.

There are also MULTIPLE "data" sheets (about 20), each containing a
table - These sheets are important!
Each of these tables references a specific variable along the x and y.

I need a specific number transposed onto the MASTER sheet that was
taken from one (1) of the DATA sheets (a different sheet almost every
time, may I add) and I can't figure out how to fetch the specific x/y
co-ordinate of the answer.

Perhaps I need to provide more details? Yes, I believe I do. I can
imagine your glazed stare already. ;)

Data provided by the user for this aviation-related problem:
- Temperature
- Altitude
- Flap Setting
- Aircraft Weight

DATA sheets are broken down as follows:
- Each sheet is for a specific Flap Setting AND Altitude
- Table is set up with Weight up the vertical (y) axis, versus
Temperature along the horizontal (x) axis.
- The plot of x&y will give the user a specific speed for takeoff. <-
THIS IS THE # I NEED ON THE MASTER!

I need a formula (or method) to take the data provided, refer it to
the CORRECT data sheet (flap setting & altitude) as well as find the
correct x/y (speed) cell given the variables.

As it stands right now, I created a drop-down list that encompasses
the appropriate temperature, altitude, flap setting, and weight
ranges... But for the life of me, I cannot figure out how to use this
to grab the information from the charts on the data sheets.

I wish I could be clearer... But if you think you can help and would
like more details, please feel free to email and I will send a
snippet.

Thank you so much,
Craig