All depends upon the direction you're approaching. Unless it's a straight in app I use this... dme distance direct to the field plus double what ever distance final you expect. Now use you ROD Calcs to sort the rest.
Take the first two Numbers of the G/s then divide by 2 ie G/s 300kts =30/2 = 15(x100'/min) 1500'min
Just try and build up a mental Circuit in your mind then 'unfold it'
All about trying to see the picture
