fortune, hazard, luck, chance - an unknown and unpredictable phenomenon that causes an event to result one way rather than another; "bad luck caused his downfall"; "we ran into each other by pure chance"

accident - a mishap; especially one causing injury or death

near miss - an accidental collision that is narrowly avoided

derailment - an accident in which a train runs off its track

ground loop - a sharp uncontrollable turn made by an airplane while moving along the ground

misfortune, bad luck - unnecessary and unforeseen trouble resulting from an unfortunate event

puncture - loss of air pressure in a tire when a hole is made by some sharp object

trip, slip - an accidental misstep threatening (or causing) a fall; "he blamed his slip on the ice"; "the jolt caused many slips and a few spills"

collapse - a mishap caused by something suddenly falling down or caving in

crash - (computer science) an event that causes a computer system to become inoperative; "the crash occurred during a thunderstorm and the system has been down ever since"