How safe is flying? There are the risks you know about. There are some you probably don't. And then there are unknown unknowns. NASA did a survey of both commercial and general aviation pilots, and the data was apparently so troubling that they have refused to release it:

When The Associated Press sought the data under the Freedom of Information Act, the request was rejected by a high NASA official. He said releasing the data “could materially affect the public confidence in, and the commercial welfare of, the air carriers and general aviation companies whose pilots participated in the survey.”
— Via The New York Times

WTF? We can't release the data because it might scare people? (As Dr. Christian Szell might say, "Is it safe?") A House committee has promised to investigate:

[C]hairman of the Investigations and Oversight Subcommittee of the House Committee on Science and Technology, wrote in a letter to the NASA administrator, Michael Griffin, that possible damage to the image of the airline industry “does not appear to fall within any of the exceptions” to the Freedom of Information law, and that not releasing the information would be contrary to NASA’s mission of improving the safety and efficiency of airplanes.
— Via The New York Times

Kind of makes you wonder what's in the report. Various media outlets have mentioned bird strikes, separation failures, and runway incursions, citing anonymous sources. The House committee better fasten their seat belts.