One day, a lady decides to take helicopter lessons. She goes to the flying school, but the teacher is busy that he says he will instruct her by phone. So she gets in and flies up and she does so well that the teacher tells her to go higher and higher and so on. After a while, he lets her go on her own, but all of a sudden she crashes. The teacher asks her what happened, and she says, "I got cold so I turned the big fan off."