  DO-178B was based on the consensus of the avionic software community as it
existed in 1992. Twenty two years after publication, we have no publically
available experimental data as to its efficacy. It appears to work extremely
well, since there have been no hull loss accidents in passenger service
ascribed to software failure. This is a comforting and surprising result.
However, if we don't know why DO-178B works so well, there is a danger that we
could stop doing something that really matters, which could lead to an
accident.
