An aspect of this is "why are we here?". This conversation needs to be useful for that. Doesn't need and shouldn't be "rudely useful", but still, let's try and

An aspect of this is "why are we here?". This conversation needs to be useful for that. Doesn't need and shouldn't be "rudely useful", but still, let's try and make some progress. This is true even if your purpose is to pass the time pleasantly by chatting with your neighbor until your airplane boards. If you are merely humoring that person, then okay you have no interest and there is no point. This is something that bothers me with "safe" ways to conversation. So safe as to be pointless. And same for "endless answers" and "derailing the conversation" - which might be fun material perhaps in some nerdy way, but might as well kill a conversation. Striking a conversation is a skill, so is keeping it on track.