"Steven P. McNicoll" wrote

It assumes nothing at all. If a pilot reports he's in the
clouds, then any other
aircraft that is within 2000 feet horizontally, 1000 feet above,
or 500 feet below
the reporting aircraft MUST be in IMC.

ATC's definition may be different, but I found these defined on
the web.


From FAR Part 1
IFR conditions means weather conditions below the minimum for
flight under visual flight rules.

This seems to be the definition that you are using for IMC.



From http://www.visi.com/~lindowdy/aviation/glossary.htm
Glossary of Aviation Terms
IMC instrument meteorlogical conditions; unable to see visual
references outside the plane

This seems to be the definition that most mortal pilots use.

Bob Moore