"three-eight-hotel" wrote in message
ups.com...
You described being able to see things "down" but not "at a slant" in
haze
at 3000'. At that altitude, if you can't see prominent objects 11
degrees
below horizontal, you have less than 3 sm visibility (and if you can't
see
prominent objects 35 degrees below horizontal--still nowhere near
"down"--you have less than 1sm visibility).

Any typical day in the Sacramento Valley is going to involve haze,
except for those perfect days. I am certain that I have flown in
conditions of 10, 20+, to almost unlimited visibility, where I couldn't
see Mt. Diable, 90ish miles away, at an altitude that probably put it
at 11 degrees below horizontal.

Of course--it varies with altitude. At 3000', 11 degrees below horizontal
gives you just under 3 sm slant distance. At a much higher altitude, 11
degrees below horizontal gives a much greater slant distance.

Standing on the ground at the departure and destination airports, I can
comfortably say that there was 5 sm visibility, as I was amazed at how
different things could look from the ground and in the air. An
un-intentionally omitted fact was that the flight occured around 4:30
p.m., which added another parameter, being the setting sun. The
setting sun and haze could have likely made for poorer visibility, as
I was flying East to West???

Quite likely. But flight visibility is defined by how far you can see,
regardless of the factors that contribute to limiting that distance. And the
VMC/IMC visibility distinction is defined with regard to *flight*
visibility, not ground visibility.

Another fact that I will humbly admit to, is that my gauge of distance
probably leaves a lot to be desired. I welcome any and all comments to
how people best gauge distance.

Yup, it's hard to judge distance, especially when the air is very hazy.
Calculating the slant distances that correspond to various altitudes and
viewing angles can be helpful. An obvious easy one to remember is that at 30
degrees below horizontal, the slant distance is twice your altitude
(neglecting earth curvature).

I'm certainly not trying to be argumentative and appreciate your post,
nor am I looking to get flamed for flying VFR into IMC, which I assure
you, I would not be comfortable doing or be happy about, if I had let
it occur.

I believe you. But with no flame intended, and with all due respect, your
description (seeing things in the down direction, but not at much of a
slant, from 3000') makes it seem likely that your flight visibility was
*nowhere near* VMC. In fact, if you couldn't see prominent objects from your
altitude 35 degrees below horizontal, the conditions were not only IFR but
LIFR! (Of course, all this applies when you are *in* the haze rather than
*above* the haze.)

Even if you can manage to aviate and navigate without instruments while
flying VFR in IMC, you don't have adequate means to see and avoid anyone
who's legally flying IFR near you. So you're betting their lives that
you
won't happen to collide with them.

As I said above, the visibilty on the ground, after arrival, I would
comfortably call 5 miles.

But that's what not defines the difference between VMC and IMC. What matters
is *flight* visibility, which (as your story vividly illustrates) can be
much less than ground visibility. And it makes sense that the rules refer to
flight visibility, because a primary reason not to be VFR in IMC is the need
to see and avoid other aircraft--and that ability depends on your flight
visibility. (Again, my intent here is not to criticize, but to
constructively point out a vital distinction that you and perhaps other
pilots here may have forgotten.)

Thanks Gary! Your point is taken! I "did" take a 10 minute flight for
granted, and will no longer depend on a forecast and a pop-up and see
how it feels report for current weather. I will "always" get a
breifing at least one hour prior to departure.

That's a good idea too, but the same situation could well have arisen even
with a more up-to-date briefing. Once you take off and discover sub-VMC
flight visibility, the briefing becomes moot.

You might want to file an ASRS report on this flight--not only for your
legal protection (most likely no one noticed anyway), but also because this
is exactly the sort of event that NASA hopes to learn from in order to
improve aviation safety. As do the readers of this newsgroup, so thanks for
your post!

Regards,
Gary