I remember it very well too. I was sitting at the computer and had the TV on in the background. I was hacking away at something - I think I was on vacation or working from home. Suddenly Jutta came in and said that a plane had crashed into the World Trade Center. We briefly discussed what might have happened - possibly an error in the flight control system? Meanwhile, I switched over and watched the images. Shortly after, the second plane crashed into the other tower. It took me a long time to believe what I was seeing. I still had some hope that it was an error in the flight control system, but then the plane hit the Pentagon and after that it became clear that it must have been a terrorist attack. After that, I spent hours trying to find more information, flipping through news channels all day, trying to access websites and looking for where to find news. In between, I called the office and spoke with colleagues - they had only heard about it on the radio up to that point. Dirk Steins has the original article.