Decent people don't need a code of conduct.
There's been pressure on the D Language Foundation to have a CoC. I've consistently refused one. The only thing I demand is "professional conduct". Sometimes people ask me what professional conduct is. I reply with:
1. ask your mother
2. failing that, I recommend Emily Post's book on Business Etiquette.
And an amazing thing happened. Everyone in the D forums behaves professionally. Every once in a while someone new will test this, their posts get deleted, and then they leave or behave professionally.
I meant for flights (edited accordingly). In both cases I think "don't be a dick" probably would go most of the way
You'll get treated better by the staff if you dress better.
I'm less concerned with the behavior of the staff than the behavior of the other passengers