I was on a plane recently, listening to the usual safety briefing, when I heard the flight attendant say that “it is a violation of federal law” to ignore illuminated safety signs, such as the “fasten seat belt” sign. I was surprised because, on another flight, I had overheard a flight attendant tell a passenger who wanted to use the bathroom while the “fasten seat belt” sign was illuminated that she couldn’t authorize him to get out of his seat but that she wouldn’t stop him either. The sense I got from that previous exchange was that the sign was essentially a recommendation. So, I decided to look into it.