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.