She is only allowed to fly to her destination, not anywhere else. She notices that she is not where she should be, that she cannot progress to where she was told to go, and she careens out of control when her wings won't flap anymore, and she crashes.
"There isn't some - bizarre spell over everything making it impossible to say or impossible to be believed, there hasn't been a long conspicuous history of people trying and unpleasantly failing...?"
"I think you may be overestimating the degree to which anyone consciously assesses the risks," he says. "My personal reasons for not having gone public include the fact that I don't have a good reason to try it in the first place and the fact that it observably hasn't happened despite the lack of overt obstacles."
"Do you have any theories about what the covert obstacles might be, if they exist?"
"I don't expect it to be useful to the project to announce magic to mortals in general, but having to operate as if it's a secret is an unhelpful constraint..."
"My advice is that you refrain from blatantly announcing the existence of the supernatural to mortals until you anticipate some direct benefit from doing so. I don't know that there is some covert obstacle that might get in your way, but I don't know that there isn't, and it seems plausible, so it's worth waiting until you'd get something out of it that might make up for whatever unknown inconvenience would befall you."