Mentioned the National Transportation Safety Board on the ground at San Bruno. The board is there because the disaster involved a transportation system. The National Transportation Safety Board is not your conventional bureaucracy. It doesn't promote industries and it can't regulate them either. It's strictly there to make investigations on a wide range of public transportation incidents, then issue preliminary reports and final findings on probable cause. It also maintains a list of the most pressing safety issues. Here's a recent piece on the need for professionalism among regional carriers, highlighted by the NTSB and others. The Board can bring attention, but not force action. Sometimes the lack of an industry or congressional response is frustrating. But I'm glad the NTSB is on the job and it's a model for other nations.
The Chemical Safety Board has a similar mission when it comes to all kinds of plants that process reactive chemicals, not just refineries but factories.
A good description of the NTSB's process is in Bill Adair's book, Mystery of Flight 427, Inside a Crash Investigation. Here's a summary of his book. It's about how investigators puzzled out a mechanical flaw in the rudder actuator that caused a Boeing 737-3B7 to crash six miles from the Pittsburgh, PA airport in 1994.
While investigators head for the site of a disaster as quickly as they can (they keep "go bags" packed and ready) a complex investigation takes time. A year to two years is common, depending on workload and complexity. The principal parties in a major incident, which can be the airplane manufacturer and the pilots' union in the case of an airliner crash, designate representatives to participate in meetings and to review the evidence. Sometimes evidence takes months to locate, such as an engine part that comes off a plane and lands in in a cornfield short of a crash site.
While investigators do have to form hypotheses along the way, as they work toward a report to the board, their ethic is to keep an open mind and let the facts set the course. This can be tough because sometimes key parties get very nervous about what a rigorous investigation might turn up.
Still we can be confident in the board's neutrality. At one time it was connected to the Department of Transportation, but Congress cut those ties in 1975.
The board finishes its work with a "probable cause" finding. Sometimes there is a public hearing. Reporters benefit from the stacks of reports issued and available on the Net. And I think the board's work also benefits from the press's involvement, including the investigative pieces.
I had the chance to meet now-vice chairman Christopher Hart when we were presenting to the Chemical Safety Board staff and members. I was impressed. His specialty when an assistant administrator for system safety with the FAA was the promotion of statistical methods to pick up precursors well before they turn into failures: it's called GAIN, for Global Aviation Information Network. GAIN uses principles lined out by operational research in World War II, which improved military tactics with statistical analysis.
Here's a link to proceedings in 2003 on close-call analysis to improve railroad safety -- a summary of Chris Hart's talk on the application of GAIN principles starts on page 27.