Hardly useful. However, if we go to the Instrument Procedures Handbook, we see:
...and that language is quoted from the ICAO. That definition is also consistent with the tolerances for the final segment of an instrument approach in the IR PTS. That works for me. 3/4 scale might work for enroute/terminal operations, but for approaches, I'll stick with 1/2 scale.
Good points. Reporting established isn't nearly as important as being established before leaving your last assigned/published altitude. Descending too soon has killed too many people. Stick with what JC and I said about when you are "established", and you'll live to make that report.
So how many times during the approach do you report "established"?But, but, but that's the only time I'm on the localizer...
There are many places where you are vectored to join a localizer only a few miles outside the FAF. In those places, you may be vectored to join the localizer with the last vectoring altitude being higher than the published altitude for the intermediate segment you are joining. In that case, you cannot safely (or legally) leave the last assigned altitude for the published intermediate segment altitude until "established" on the localizer.
Different issue, but still important.
So how many times during the approach do you report "established"?
Yes, that plus there are also places where radar vectors to final are not available, you fly the full published approach initiating via a procedure turn or DME arc the published minimum altitude of which might likely be higher than the minimum altitude of the intermediate segment between localizer intercept and glideslope intercept.
Even if everything goes right it requires a pretty good rate of descent to make it work, now factor in the fudge factor plus a wind out of the southeast quadrant that's delaying your final approach course intercept while blowing you closer to the airport and it could be tempting to call yourself "established" and start descending early..........until you think about that huge (tall) grain elevator 
So you see, in some cases it's best to know exactly at what point it's safe to consider yourself "established".
Here's a good reason to understand at what point you should consider yourself "established" on the final approach course and OK to start descending to MDA, link is to the NDB 29 approach to Wolf Point, Montana.
http://155.178.201.160/d-tpp/1402/06018N29.PDF
Now you're flying this one the purist way, ADF and timing to determine how far to go outbound while insuring you remain within 10 miles of the beacon. Back in the "good ol' days" the procedure turn minimum altitude was a few hundred feet lower than it is now but it was pushed up to 4300 about fifteen years ago to allow for a huge (tall) concrete grain elevator that was built out in the PT area. Keep in mind that you're determining distance outbound by the imprecise method of estimating groundspeed for timing so you prob'ly should fudge it a little on the short side to insure you don't go outside the ten mile limit. Also note the NDB is located about a mile & a half beyond the center of the airport. Now let's say our estimating and timing is perfect and we intercept inbound at 8 miles, to descend 1420' from PT altitude of 4300' to MDA at 2880' in the five miles that'd put us on a 1 mile final to runway 29 for a straight in .................
later comment; here's something I just noticed, why would we have an MSA that's 100 feet lower than the minimum procedure turn altitude?, charting error perhaps
Yes Bob, I'm certainly aware of that. But still
.........it looks like they're sayin' "you're gonna' hav'ta do the slam-dunk here to avoid crashing into the grain elevator, but hey....if you're a hundred feet low?, don't worry about it :wink2: That's kind'a like the sign that said "NO TRESSPASSING, and if you do....please close the gate". 
