Fire at 41,000 feet
My first flight on on NASA's Kuiper Airborne Observatory was interrupted by a smoking HP power supply. The telescope data system was all HP equipment (2100 mini-computers or earlier) and something shorted out during the flight. As the smoke increased it started to get everyone a little worried. Fires on airplanes are not fun. Everyone went back to their seats and someone grabbed a fire ax and started looking for some equipment to attack. The system had a ground fault protector that finally tripped and shut down the whole system. We had to land with the telescope enclosure open (a huge open hole in the side of the airplane) which had never been done before. Not exactly the best flight to start out with.
This is a link to some photos I took on the airplane: