Originally Posted by
gophish11
So definitely less than "conventional" radar separation and less than you'd want during IFR, but it was during VFR flight in perfectly stable air, so probably acceptable given the conditions.
You're conflating flight rules Instrument/Visual Flight Rules with flight conditions Instrument/Visual Meteorological Conditions. Flight rules....are the the rules you fly by. Who controls you, what procedures you fly, what ATC is responsible for, etc. Meteorological Conditions are whether you can stay upright and navigate just by looking out the window (to oversimplify).
Scheduled airline flights are pretty much IFR all the time. You can fly IFR in VMC, and you can legally fly VFR in IMC (think "moonless night over the desert").