<my point again is that most always the errors are inadvertent and unintentiona>
or due to a lack of resources or trying to fix a problem and later causing a problem...
consider the transponder AD...going to standby after 5 seconds etc...obviously well intentioned so as not to trigger a 7700 alarm etc...but better the transponder be on with the wrong code than off with the code improperly set...
at least TCAS would work with the wrong code.
AS with the COMAIR thread, swiss cheese lining up...just one thing...if you want more slices of swiss cheese with the same amount of milk, you have to have more holes...