Right on target Tom.  Pun intended.  These creatures are called "targets".

The USAF has had a system in place for what....30-40 years?

Robisan and other independent labs have been pushing for this kind of stuff ever since at least the late 80s.

Jack Crawford has explicitly told me that IPC legal believes assessment of the "human part" too-hot-to-touch.  And actually the "Visual Acuity Testing" from IPC-QL-653 is supposed to be stricken in the next revision.

My father was on the front lines arguing this issue for the Navy against the union.  To the best of my knowledge the Navy won, but that was 20 years ago.

Is the human the largest ingredient in the "uncertainty of observation" budget?  I don't know.  Probably.  At any rate, it sure is hard (if not impossible) to assess the system without the observer.  

Today-- quality optical system manufactures state resolution on the device's specs.  You could simply use these numbers in conjunction with IPC-OI-645 to build the "better than nothing"  table.

The bottom line is... the bottom line.  As features become smaller and smaller, it will without question, become cost prohibitive to use human inspection.

Unless, of course, you redefine your sample.  The microsection part of 600/6012 has always used this human inspection-very small sample model.

Chris

Chris Mahanna
Quality Manager
Robisan Laboratory Inc.
6502 E 21st Street
Indianapolis, Indiana 46219
phone 317.353.6249
fax 317.917.2379