"Steven P. McNicoll" wrote in message
ink.net...
I worked a flight above FL600 just once. About fifteen years ago I was a
controller at Chicago Center working traffic in the Madison, WI, area. A
NASA ER-1 departed MSN requesting an unrestricted climb to FL610.

What's an ER-1?

I
coordinated with the high altitude sector and issued the climb. He went
up
like a rocket! The Mode C readout couldn't keep up with him. Shortly
after
he reported out of FL600 and cancelled IFR, the Mode C read FL600. I
asked
a Data Systems Specialist about it and he told me that FL600 and higher
will
read out as FL600.

Cool!!!