To avoid further discussions, I changed the subject title from "incident" to "accident", according to
http://www.thefreedictionary.com
in·ci·dent (ns-dnt)
1. A definite and separate occurrence; an event. See Synonyms at occurrence.
2. A usually minor event or condition that is subordinate to another.
3. Something contingent on or related to something else.
4. An occurrence or event that interrupts normal procedure or precipitates a crisis: an international incident.
adj.
1. Tending to arise or occur as a result or accompaniment: "There is a professional melancholy . . . incident to the occupation of a tailor" (Charles Lamb).
2. Related to or dependent on another thing.
3. Physics Falling upon or striking a surface: incident radiation.
ac·ci·dent (ks-dnt, -dnt)
1.
a. An unexpected and undesirable event, especially one resulting in damage or harm: car accidents on icy roads.
b. An unforeseen incident: A series of happy accidents led to his promotion.
c. An instance of involuntary urination or defecation in one's clothing.
2. Lack of intention; chance: ran into an old friend by accident.
3. Logic A circumstance or attribute that is not essential to the nature of something.