I was reminded in 1992 when I bought a Cessna Cutlass (172RG), my first retractable gear airplane, to stay humble because there are only 2 kinds of retractable gear pilots - ones who have landed gear up and ones who will. (I thought about that and then deep down I thought it could never happen to me. How could anyone be so distracted to forget to put the gear down?)
Fast Forward to 1997. I had just bought a 1996 Mooney TLS Bravo and a friend needed me to drive him up to catch a commercial flight in Austin TX. No problem, I'll fly you to Austin Mueller (now closed). He had flown with me many times and knew that hot starts in Texas summers can be tricky. We went over it before we ever left the ground. He was going to exit the airplane, get his bag, shut the baggage door and walk behind the airplane to the FBO for his ride to the terminal while I kept it at idle and didn't have to shut down. We landed, taxied, he exited. I got my clearance, taxied, took off and shortly after take-off I heard a loud bang from the back of the airplane - the baggage door has popped open on my new airplane. I was sure it had probably exited the airframe and had taken the tail section with it. I let the tower know what happened and that I was coming around to land on the perpendicular runway - all the way picturing what my airplane must look like. I turned final and wanted to get this thing on the ground to assess the damage. On final a Delta pilot waiting for take-off, who had heard everything, says "Mooney, check your gear down". I got that horrible feeling. I would like to think that I would have made a short-final gumps check, but I'm not sure. After all was said and done after landing and then taxiing to the FBO and looking over the airplane, I closed the baggage door, locked it and there wasn't a scratch or a bend anywhere on the airplane. I had turned a minor distraction into what could have been a major problem. After that I realized it can happen to anyone - all it takes is something out of the ordinary thrown in the mix. Don't ever say it couldn't happen to you.