Trialled:

1974

Even methods to stop airplane hijacking can be totally absurd. Now here comes the insight into the genius; there is a hypodermic syringe built into every seat on the plane! According to the inventor, the needle is driven through the seat cushion, instantly sedating or killing the would-be terrorist. Ouch! But what if the crew hits the wrong button or the hijacker won't sit down? Erm?