20,000 feet is about 3.3 nm, so 3.3nm/min*60min/hr is about 198 nm/hr
That's a fast rate of descent!!!

Dan Moos wrote:
I live in Washington state, home of McCord airforce base. They have C-17's
there, and the local news station just stated what seems to me to be an
unbelievable fact. They reported that th C-17 can descend 20,000 feet in 1
minute. Now I'm a general aviation pilot, and 2,000 feet per minute is a
fast descent in my world. Is 20,000 fpm with a C-17 for real, or did the
news (KOMO channel 4 for you other western Washinton folks) get it wrong?