Nigel Packham, Associate Director, Safety and Mission Assurance, NASA Johnson Space Centre
Is it Safe? This seems to be a reasonable question to ask when trying to assess whether or not to undertake a particular action or endeavor. Indeed, in the realm of Human Space Flight, this is a commonly asked question. However, when you contemplate strapping your best friends into a capsule atop a launch vehicle capable of producing 7 million pounds of thrust for 8 minutes, you rapidly find out that asking that question is nonsensical.
Human spaceflight is inherently risky, and certainly not “safe”. The better standard that is used by NASA and other high risk organizations is to ask the question, “Is it Safe Enough”. There will always be risk in such endeavors. The challenge is to identify and manage that risk so that the remaining, or residual risk is acceptable.
Ideally, the level of risk can be expressed in quantifiable terms of the likelihood of the event happening. We are all familiar with the risk of being struck by lightning being over one in a million (or 1:1,000,000). In human spaceflight, typical residual risks of losing the crew (LOC) are in the 1:200-1:250 range. But can you guess what the real risk of the very first Shuttle flight, STS-1, was back in 1981? I say real, because the LOC risk back in 1981 was estimated to be somewhere between 1:1,000 and 1:10,000.
This presentation will discuss the management of risk in several non-aerospace fields and compare the various methodologies to that used in Human Spaceflight.
