  Each new concept of operation and equipment generation in aviation becomes
more automated, integrated and interconnected. In the case of Unmanned Aircraft
Systems (UAS), this evolution allows drastically decreasing aircraft weight and
operational cost, but these benefits are also realized in highly automated
manned aircraft and ground Air Traffic Control (ATC) systems. The downside of
these advances is overwhelmingly more complex software and hardware, making it
harder to identify potential failure paths. Although there are mandatory
certification processes based on broadly accepted standards, such as ARP4754
and its family, ESARR 4 and others, these standards do not allow proof or
disproof of safety of disruptive technology changes, such as GBAS Precision
Approaches, Autonomous UAS, aircraft self-separation and others. In order to
leverage the introduction of such concepts, it is necessary to develop solid
knowledge on the foundations of safety in complex systems and use this
knowledge to elaborate sound demonstrations of either safety or unsafety of new
system designs. These demonstrations at early design stages will help reducing
costs both on development of new technology as well as reducing the risk of
such technology causing accidents when in use.
  This paper presents some safety analysis methods which are not in the
industry standards but which we identify as having benefits for analyzing
safety of advanced technological concepts in aviation.
