TABLE OF CONTENTS 
"If I had 8 hours to cut down a tree, I'd spend 6 hours sharpening the axe."
A. Lincoln
Designing a single component may be a relatively simple matter, one that a single person can handle. Designing any large system however, whether it's a car, a computer, or an airplane, is typically beyond the ability of any single individual. The instrument or control system engineer should not feel that all the tasks associated with designing a safety instrumented system are his or her responsibility alone, because they're not. The design of a system, including a safety instrumented system, requires a multi-discipline team.
"Hindsight can be valuable when it leads to new foresight."
P. G. Neumann
Hindsight is easy. Everyone always has 20/20 hindsight. Foresight, however, is a bit more difficult. Foresight is required, however, with today's large, high risk systems. We simply can't afford to design large petro-chemical plants by trial and error. The risks are too great to learn that way. We have to try and prevent certain accidents, no matter how remote the possibility, even if they have never yet happened. This is the subject of system safety.
System safety was born out of the military and aerospace industries. The military have many obvious high risk examples. The following case may have been written in a lighthearted fashion, but was obviously a very serious matter to the personnel involved. Luckily, there were no injuries.
An ICBM silo was destroyed...
