This is only one reason why I keep asking for a spreadsheet app included in the iFly GPS app. I have the SR/SS spreadsheet in my tablet. It's not a very big calculation. I also have the moon cycle spreadsheet on my tablet but that one does require quite abit of data and calculation. Anyway, I find both of these spreadsheets very useful when flying long x-countries. I won't think of flying very far from home without all of my aviation spreadsheets! - Jim Williams