What would you do if someone panicking during take off or landing?

First what I would do, it is to contact pilots telling them about the situation and asking how much time do we have before landing/before seat sign will go off, in case of take off. In that case after a go around, with the Captain’s permission, I would have time to approach a passenger asking him/her to calm down, reassuring about the safety onboard. Taking back my seat I would keep an eye on him/her to make sure that everything is under control”