To dream of being in this event is a feeling of not only a dramatic negative change in your life, but also to everyone around you as well as your envorment.
A very negative symbol and should be meditated upon.
To dream of witnessing this event is symbolic of feelings of helplessness in the face of a great tragedy. In prohetic dreams this heralds a great change in the distant future (planes are associated with great distance). This change may not be negative.... Encyclopedia of Dreams
Psychological / emotional perspective: A crash as in a collision suggests a traumatic occurrence, perhaps by not paying attention to detail. Crashing out would suggest losing a hold on reality.... Dream Meanings of Versatile
Dreams about being in a car or motorcycle crash mean your beliefs or lifestyle are clashing with someone else’s. It may also represent a recent shocking situation you were involved with. Dreams about airplane crashes mean you have set unrealistic goals for yourself.... My Dream Interpretation