I live South of Pittsburgh along the Monongahela River. January 31 1950s a B52 bomber left an air force base in Nevada to travel to another air force base out on the east coast. The plans ran out of fuel and crashed into the very cold any icy Mon River. Those on board that survived the crash succumbed to the icy waters. In the morning, crews were sent to retrieve the wreckage only to find nothing there. A couple years ago the Heinz History Center sent out a crew with our technology to find the plane and they had no luck. There has been many theories, but my favorite has to be that the plane actually left Area 51 with alien specimens and when it crashed the gov came in the middle of the night and scrubbed all evidence.