The term System in Safety Management System refers to the system of controls applied to the operational processes of a certificate holder, and that produces safety as its output. This system is characterized in the three box model as a protection system, in contrast to the production system that delivers freight and passengers to their intended destinations, and the oversight system exercised by FAA. The use of the term system to describe such an assembly of processes and controls is somewhat of a stretch. To the extent that such an assembly can be called a system, it is an open system, using the terminology described by Gerald Weinberg in the standard textbook on the topic “An Introduction to General Systems Thinking.” There are multiple factors that affect safety that are not under the controls of Flight Standards and the Certificate Holder such as the environment (Canadian Geese, to mention a recent example), Technology (until recently, we did not know how to inert aviation fuel), and economics (certificate holders have to be able to stay in business). Furthermore, the output of an SMS is safety. But safety is not directly observable. To the extent that it is observable, it is as the absence of undesired outcomes. Thus it is difficult to determine whether the system is working, since the absence of events may be due to other causes than the ones under AFS and certificate holder’s control.