There was a lot of fear mongering. Y2K is actually when I realized that I can’t believe everything on the news. They kept reporting on it as an imminent threat for long after it was known that the engineers had patched the issue, and chances of problems were very low. As far as the planes go, the big threat was from air traffic control shutting down, and having thousands of planes in the air with no way to track all of them and safely route them in for landings. Plus there were concerns about navigation. So there were definitely issue, just not fall out of the sky issues.