This　paper　presents　an　approach　to　learning　lessons　from　past　accidents　through　retrieval　of an　accident　database.　First，a　databas management　system（software）and　ah　experimental　construction　of　the　database　are　discussed.　Then，tags　and　their　values　to　describe　the　accidents　are improved　and the database　is　reconstracted　accordingly. Finally，results　of　the　retrieval　are　given，showing　how　they　can be　used　to　improve　safety．

Faut　trees　for　real　systems　can　get　very　complicated，　and　algorithms　for　tree　generation　are required to be applied to complex systems．This paper presents an algorithm for the synthesis of fault trees　in　control　systems　which　employ　the　combination　of　feedback　control　loops，and　the　one　of feedback　and　feedfoward　control　loop.　The　algorithm　is　an　extension　of　the　companion　paper　Part 1 of this series．It should be noted that the feedback control loop is located in the top structure of fault trees，but　contains　the　feedfoward　control　loop　as　one input.