George Spafford wrote "there are a number of behaviors that can dramatically increase the odds of human error yet organizations fail to manage them". He identifies a wide range of factors that make human errors more likely including: complexity; deadlines; fatigue; multitasking; poor planning; insufficient testing; lack of change management ... and many more (just read George's paper and I'm sure you will think of more).
George continues, "some organizations may have multiple behaviors that when combined further increase risk levels. Organizations must take a careful look at their culture and processes to understand and subsequently manage the level of human error being introduced." 'Taking a look at' culture and processes is easy enough but changing them (especially the culture) is a different matter entirely. That said, George's list of issues implies a whole load of options for those willing to take up the challenge.