Second vote for Krav. My instructor has played with plane,bus and train scenarios. The biggest problems are lack of room and unwillingness of other passengers to get involved - the 'Don't upset them' mindset..

My daughter has worked out that airlines will allow her to wear her favourite chopsticks in her hair AND allow a pencil sharpener in her pencil case.

Like Dewey said a Cross pen or a Rotring is also a useful tool, espcially for filling the green card on the flight