Who is Brian Perri?

And why is he still missing after 18 days?

I'm all for volunteers looking for a missing individual.  That is, I'm all for this exercise one or two or three or four days after an individual (hiker/survivalist/backwoodsman) goes missing.  18 days?  He's way past the point of needing water, and on the verge of becoming incapacitated from lack of food.  Yelling his name when you go off trail is admirable, but at this point, useless.  Either he is dead, unconscious/comatose, or, split town on the midnight train, and used the summit of Mt. Meeker as an excuse to gain a good head start.

Let's start actively considering the latter before too much longer, shall we?  Let's start asking ourselves about bank accounts, recent loves found or lost, any musings he's made in the past year about "ditching all of this and becoming a rail-hopper".  Because the mountains are big but not that big, and wild animals are scarce but not that scarce, and after 18 days of not finding a live body, it seems more and more likely you are going to find a dead body, or no body.