I had been scheduled to travel EWR-LGW-STO on 9/13th. Given the tragic events, I cancelled on 9/12---with the thought that my seat could be better used by someone who really needed to be there. CO then cancelled my flight. They gave me a full refund, which I then proceeded to use to rebook the same trip on 10/18. I am not at all worried about travelling abroad, but it is a very personal matter and if you feel in the least bit concerned, and that concern may spoil your trip--then you should cancel. Most airlines are still allowing full refunds given the situation, just call them and explain.