Believability (not to mention crew safety) demands that the 
Enterprise environmental support systems be extremely reliable with many 
redundant backups. The problem from a television standpoint is this makes it 
a little tough to create story situations in which our crew can be threatened 
by life support failure. In one episode, ÒBrothers,Ó writer-producer Rick 
Berman needed all bridge atmospheric support systems to fail. He 
rationalized it by having Geordi express amazement that seven independent 
safety interlocks had been bypassed, thereby acknowleding that the ship is 
indeed designed to make such failures extremely improbable.  Æ