Individual and often uncontrollable circumstances have resulted in nearly all facility engineering functions, from conceptual planning to project startup, being contracted to outside consultants at one time or another.
Uncontrollable situations have been negative experiences, but leads to other things. 
mnli hypothesis: Uncontrollable situations have been negative experiences, but leads to other things.  premise: Individual and often uncontrollable circumstances have resulted in nearly all facility engineering functions, from conceptual planning to project startup, being contracted to outside consultants at one time or another.