"Andrew Gideon" wrote in message
online.com...

How could "near miss" be defined in this case, with one (or both, out of
curiosity) aircraft instructed to maintain visual separation?


"Near miss" is not defined, the proper term is Near Midair Collision. A
Near Midair Collision (NMAC) is "an incident involving one or more aircraft
in which a hazard or a perceived potential hazard to safety is involved."