In light of the February 1 Columbia shuttle tragedy, the importance of fault tree analysis and how it relates to the safety profession has garnered greater interest, says Mark Hansen, CSP, PE, president of the American Society of Safety Engineers.

"Fault tree analysis is a logical and structured process that can help identify potential causes of system failure before the failures actually occur," says Hansen. "This powerful technique has long been a staple of safety engineering and the safety profession and is often used as a design tool, which can help ensure that product performance safety objectives are met. Fault tree applications are used extensively in analyzing manufacturing equipment, automotive subsystems, aircraft, nuclear power plants, public utilities, or other complex technical systems.

"The fault tree is a logic diagram that traces all the events that might lead to an undesired event being reviewed. It reasons backward to identify the way the undesired event might have happened. Specific contributing factors are studied and analyzed to see how it could have happened. The tree helps to identify failures and consequences that may not have been obvious.

"The technology used by NASA in building the space shuttle is a good example of how fault tree analysis is used. NASA is one of the pioneers in using systems safety-related approaches to design and implementation and has historically been looked upon as a significant contributor to the system safety body of knowledge.

A key resource on systems safety is the book "System Safety Engineering and Management," Second Edition. Authored by Harold E. Roland and Brian Moriarty, this book is recommended for safety professionals seeking to earn the Certified Safety Professional (CSP) designation, which is an accredited certification offered by the Board of Certified Safety Professionals (BCSP).

For more resources on systems safety related issues and workplace safety for employers, employees and occupational safety and health professionals check ASSE's Web site at