Bob, the calc does not work for future PAS, but in your case you could work out the pre-PAS bit, re-run it as a wg cdr at appropriate level to work out the 2015 to 2020 bit of AFPS15 (ignore the '75 element for the wg cdr calc) then add your pre-2015 flt lt figure to the post-2015 wg cdr figure and Bob's your… well err.
Hope this helps, if not send me your details and I will have a go for you.
Last edited by Just This Once...; 1st Jan 2014 at 10:43.
Reason: Emphasised the 'future PAS' for clarity.