Intermediate Fix and lateral safety margin.

[Oddball77]

Originally Posted by Edgington

It depends on the approach, is it straight in, NDB, VOR. For a VOR approach it will taper from the IAF to the IF in the primary area from 2,5 nm to 1 nm and the secondary area from 2,5 to 0,5 nm either side of track. NDB from 2,5 to 1,25 nm in the primary area and from 2,5 to 1,25 in the secondary area

Where is this referenced?