I got the chance to sit up front in a plane in the flight levels a few
weeks ago, and it looks really close from the front window too. :-)
Especially dramatic is when you have two planes, one 1000' above you,
and another 1000' below you, passing at almost exactly the same time.
It feels like you are threading a needle between the other two
planes...

Chris

When you are at flight levels, due to the curvature of the earth, on first
apperance, the "higher" aircraft may appear to be lower, and as the distance
closes, the appearance is that he climbs from below to above, where he was
all the time.

I will agree that it is "dramatic".

BT