There are other possibilities beside "plane controlled by terrorists" - radio failure, for example (for all the redundancies, this still happens in the 21st cen

There are other possibilities beside "plane controlled by terrorists" - radio failure, for example (for all the redundancies, this still happens in the 21st century). In that case, rudimentary visual communication comes in handy. In other words, not all in-flight emergencies follow the Hollywood movie conventions ;)