This question was inspired by the events that took place on the Southwest flight from Portland to Sacramento where a woman became unruly and threatened to kill everyone on the plane when she was caught smoking a cigarette mid-flight.
In one of the comments on the linked article, a person noted how calm the person sitting next to her was even as she made these threats and other people on-board and the crew had to restrain her for the remainder of the flight.
Now, if I were the person next to her I don't know what I'd do but I don't think I'd just sit there. I feel my first reaction would be to try to reason with her and calm her down but from my experience, when someone is in such a state (clearly not making logical or reasonable actions/decisions) this approach would just make her and yourself more frustrated and agitate the situation.
What is the best ways to interact with a person in an unreasonably hostile state in a situation where keeping out of it is just not an option? The goal would be to calm the person down until someone of authority can come in and handle the situation (waiting to land the plane or for a police officer to show up).
I'd equate her behavior to that of someone acting drunk and disorderly so I'm looking for answers that could be used in this aspect as well, essentially how to communicate with and calm someone who is in an immature, illogical state of mind.
A reported followed up with an interview of the woman and she could give no reason to her actions so it's still unclear if she suffers from mental illness or was intoxicated from drugs and/or alcohol.