Yes. I do. When I'm at one end of a runway that's less than a mile, and I can't see the end of it, I don't have to be Einstien to add 2 and 2 together.
Good to see this simple observation turned into the usual pissing contest.
Not necessarily, midfield there could be a reduction in vis, or the weather could be changing at such a rate that by the time
you went to depart the visibility was below 1SM, and at one end it could be exactly a mile, or some other combination therein, regardless, he didn't break any laws, provided that from his seat at the exact time he was flying, the average
flight visibility was one statute mile or greater. Call the feds, and unless the guy is a complete idiot what's he going to say anyway? "At the time of my departure from KXYZ, the average in flight visibility from the cockpit was 1SM." At that point there is exactly nothing that the Feds can do about it because the ASOS was out of service. So even if he blasted off zero-zero without filing, there isn't a damn thing you can do about it.
You're going to jump down this guy's throat when you appear to have blasted off IFR in a single on this same flight? You want to talk risk management? Where's the difference? So you're flying a departure procedure, if you lose you're motor at 200' you're just as screwed as he is. Another question for you (and maybe you posted it already) was the obscuration due to ground fog in the vicinity, or was it a solid layer. What I mean is, where did you break out?
Maybe we should reflect on why this is a pissing contest. Why? Because people who weren't in the cockpit with the guy at the time of departure are armchair qb-ing it all the way to the endzone. The simple truth is, you don't know if the guy departed IMC or not. You may think you know, but you weren't there with him in the airplane, so you don't.
Maybe my somewhat virulent response to these sorts of threads is due in part to the "one-size-fits all" attitude among pilots. A sort of "my way or the highway" approach to flying. Flying is very different from place to place, and flying at one edge of the envelope very different that flying at the other. Just because
you personally did not approve of the level of safety of his maneuver does not mean that it was conducted in an unsafe manner. Look at the regs. If he departed with a mile of vis, was he legal? Yes. Did he have a mile of vis from the cockpit? No way to know now.