This term, used in news reports concerning the Columbia disaster, is new to me.

http://www.relexsoftware.com/reliability/faulttree.asp

cool stuff. all them funky bifurcations...

One fault in a vulnerable limb and the tree faults down.

Just goes to show that there are some dinosaur programmers still working in NASA. I learned about Fault Tree Analysis as a part of my analytical studies during my college years but no self-respecting programmer would admit to using it these days. It's so archaic.

Maybe they've run out of ways to analyse their problems........

They somewtomes look like buildings, whence the term fault tree towers (Sorry, Mr. Cleece!)