Everybody makes mistakes, it doesn't matter who you are. We all do stupid things, it is life, and human nature. Not one person on this earth is perfect. I don't think that a person's mistakes define them. Mistakes are a part of life. They help you learn, and making mistakes, sometimes, is the best way to learn, even if they are bad ones.
Most jobs will do a background check. Therefore, if you think that the charge being lessened will be on your background check, then I would be honest about it. I doubt everyone at that airline, including the interviewers are perfect. I am sure they have made plenty of mistakes in their lives too.
I have made mistakes in my life too. Granted I am young, and haven't done anything that will be on my background. I accept the mistakes I made, and wouldn't change them. I have learned and grown from them. I think at the same time you learn who people really are when you make mistakes. People who will not hire you, or forgive, are, in my opinion, much worse of a person then the person who made the mistake. I think you see straight through a person in that situation, and who they really are. If they don't hire you, or people don't forgive, etc., then they are the ones on the losing end. There is no need for them in your life, nor a need to work for that airline.