In article ,
says...

yes, I've imagined the whole trig thing. That's why I was looking at the
buildings and other higher geographic markers to get a fix on how it
appeared to be moving relative to those things. Plus, for a moment I was
stopped and pretty much next to it, although of course I was on the
ground and it was probably a couple of thousand feet up or less. And, if
it makes a difference in possible explanations, the plane was headed
east and I was moving west. I'm 99.999% sure it wasn't moving or was
moving very slowly.


You were moving in opposite directions - This is notoriously the most
difficult movement to perceive. The enormous size of the object is the other
factor that confuses our judgement. Sooner or later you are going to have to
accept the 0.001% and admit that you were victim - just as all of us have been
- to an illusion. It's actually a very common illusion, and if it's the first
time you see it, in your frequent drives near that airport, it very well may
not be the last. You must accept that your eye *cannot* reasonably appreciate
the size of the thing. You cannot know how high it is, or how far away it is
or its position relative to ground landmarks or where it would land on the
ground if it were to fall at that instant.

I have seen such illusions many times - but your suggestion that the plane
was stopped, or nearly so, is quite impossible.

G Faris