a. Estimate track miles to FAP, using any method you could find
b. [NM x 3] + FAP ALT = 3° profile, check where you are compared to that
c. use Ground-Speed / 20 to find out, what V/S will give you 3 deg trajectory and check what descent rate is being achieved
E.g
Track miles to FAP 26
FAF ALT 6000'
your FL150
IAS 290 kt, GS 370
actual V/S 2200 fpm
What do you think? My answer after yours.
