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.
[1]Illusions and unhealthy attitudes need to be discarded.
[2]Feeling helpless in the face of major tragedy.
[3]