"Incident", from Merriam-Webster:
1: something dependent on or subordinate to something else of greater or principal importance
2 a: an occurrence of an action or situation that is a separate unit of experience : happening b: an accompanying minor occurrence or condition : concomitant
3: an action likely to lead to grave consequences especially in diplomatic matters <a serious border incident>
I lean toward #3, symptomatic of a grave problem that has not been fully recognized.
But per the regulatory definition, it's an accident.