Originally Posted by
Booker
Just to add, there are a few approaches where, if one intercepts the glideslope prior to the published intercept location, the aircraft will be below mandatory minimum crossing altitudes. I believe LAX and CVG have approaches that have this characteristic.
Correct...and I believe the ILS 4R into ORD is one of these cases as well. You can absolutely follow the GS outside the FAF, just be sure that you are at or above those hard altitudes. I think you miss one or two of the outer hard altitudes by a couple hundred feet if you strictly follow the GS.