"Bob Chilcoat" wrote in message
...

The altimeter in this illustration http://en.wikipedia.org/wiki/Altimeter
is almost identical to the one in our Archer. I've been puzzling over
what that little black and white hatched area is on the dial ever since I
bought into the plane. It doesn't rotate with the Kollsman window knob,
although perhaps it rotates with the thousands hand, since it appears in
this illustration to be exactly opposite the hand. Anyone know what it's
used for? Inquiring minds want to know.


It does rotate, just rather slowly. It tells you when you're over 10,000
MSL.