In the past I was always taught it is OK to report "localiser established" when turning onto the localiser and the LOC deflection is under half scale.
However on a recent flight I was told that is a "fail" because one is not fully established.
But the ILS flying tolerance is half scale or better, all the way down, so how can it be a fail?
Sometimes you want to get the report in nice and early, before somebody else jumps on the radio with their inside leg measurements
Google is a bit ambiguous on this, and of course in the USA (IIRC, from the FAA IR) they don't use the phrase, because once you are "cleared for the ILS"
you can descend to the platform (if procedural) and just fly it all the way short of a landing clearance.
The fact that you want to fly an ILS a whole lot more accurately than 1/2
scale, especially when far out, is besides the point in this question, IMHO.
Oh dear, Peter, you've done it again.
We'll leave aside the 'fully established' thing because I think you're intelligent
enough to know what that means, but...
How many times do people have to be told to find the proper reference? Google search results are not written by the regulators. How many posts before someone turned up with the basic knowledge the question needed?
If you don't know what's in PANS-OPS, then...