Posted by Bob on February 14, 2005
In Reply to: (to go) tits up posted by Peter Sabourin on February 14, 2005
: Do not think this means "to fall over on ones back". Rather, "to go wrong". Believe origin is early floating navigation instruments in aeroplanes designed to turn over when not working so as not to mislead pilot. Undersides resembled a pair of tits.
Interesting. I've been Googling old aircraft instruments, and the "attitude indicator" on old planes have a W as you described.