Your regulator will dictate what is acceptable. For example (Australian AIP):
ENR 1.5 Section 1.21.2
Can't descend on Final until "established", defined as:
Note: “Established” means being within half full scale deflection for the ILS, VOR and GNSS, within ±5° of the required bearing for the NDB, or within ±2NM of the DME arc.
Originally Posted by Pineteam
5 degrees in our SOP which is ridiculously low considering how much the needle fluctuates in the real world. In the sim it's doable tho,
Here here!