80/20 said:
TonyC are you asking for cockpit nav indications that defines "established on a DME ARC"? (Or for the point on the arrival where you can continue the descent?)
(and later....)
80/20 said:
ICAO Doc 8168-OPS/611, Procedures for Air Navigation Services - Volume 1, which simply says:
"Established" is considered as being within half full scale deflection for the ILS and VOR or within +/- 5 degrees of the required bearing for the NDB.
80/20 - you've got the question right, and that's
exactly the type of answer I'm looking for (direct quote from an official document). THANK YOU !
I've been somewhat amazed to hear the variety of "techniques" offered on this thread. Of course, flying the centerline is desired - - doing so provides the maximum margin of error in both directions - - and, believe me, I try. But I also know that I am considered "established" and can descend (or slow or whatever the specific procedure and/or clearance calls for) once I am within 1 dot/5 degrees (1 dot is half deflection on my instruments) of a localizer/VOR/NDB course. Since we realize we can't be perfect, we accept errors within certain tolerances.
That certainly doesn't mean I TRY to maintain that 1 dot/5 degrees deflection the entire time. That would be like saying I'll double my margin of error on one side, but reduce my margin of error on the opposite side to nothing. If all of the errors are working against me in the wrong direction, and I get a gust of wind from the wrong side, I'm dead.
So, back to my original question.

Do you have a reference of the type you cited for Localizer, VOR, NDB that applies to a DME Arc? I'm inclined to believe the "tolerance" is 1 NM either side (11 DME arc, "established" is between 10 DME and 12 DME) but I have nothing in writing to support that belief.
Again, your help is appreciated !
