The reason I mention this close encounter is that I have always been
hesitant about how well I can spot aircraft at a distance. I felt
that I should have seen this guy at least a few miles out but never
did. Depending on the sun angles, the haze, the background clutter
etc., I am not completely confident yet on my ability to be able to
immediately spot an aircraft 3 or 5 miles out. And in this case I
never saw him until he was right under me.

It's not so much being able to =see= him, as being able to =notice= him.
I can see traffic many miles away, once I notice it. Sometimes
however I have to notice it again before I can see it again. Motion, a
glint of sun, a good silhouette against a cloud, these things help.

Does the ability to spot other aircraft improve with experience?

Yes, some. However, it will probably never be excellent. The field of
good vision is narrow, and the eye doesn't actually send an image to the
brain, it pre-processes it. Different parts of the retina (different
areas of view) are pre-processed differently. There's a lot of sky to scan.

Lots of experienced pilots, myself included, miss lots of targets that
are called out. That's why four eyes are better than two.

Jose
--
The monkey turns the crank and thinks he's making the music.
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