I don't have FAR with me, but I remember somewhere in the FAR that you are
responsibility for the safety of flight. So, this rule does apply to your
situation. If your passengers are drunk and wild, then it is compromising
the safety of flight. If they can handle their drink, there is no rule that
prevent them from taking ride as long as they are not in PIC. Since, I fly a
very small aircraft, I wouldn't allow anyone who is drinking onboard. There
are no specific rules that prevent them from consuming alcohol onboard. Keep
in mind, if they are drinking at high attitude in non-pressured plane, they
will get drunk on their normal consumption (lack of oxygen). They probably
don't know this. Therefore, the risk factor is extremely high in your
situation.


Toks Desalu