On Sun, 15 Mar 2009 19:45:36 +0700, Bruce In Bangkok
wrote:

Or just reduce the air pressure. I understand that is how some of the
vets put dogs down these days. No panic, just pass out.

I have been high enough in an unpressurized aircraft to die fast
without oxygen equipment. Watch my Stuka impression if the oxygen gear
fails. Basically you pass out often without noticing anything wrong.

You want to gas someone carbon monoxide is painless, unlike cyanide
which may not be. The gas chamber starts out with a breath holding
contest.

Casady