Based on the testimony that was given, it appears to me that the defense strategy on that charge was to argue that Lakin was not guilty because he hadn't been given an explicit order to be on that plane. That the process had been just informal enough that Lakin could justifiably say he hadn't consciously disobeyed a direct order.
That defense strategy ended up falling apart when the prosecution put on a witness who stated that she had given exactly that order to Lakin.
Well, there you go. I knew not about that which I was blathering. :)