One of the strangest mysteries is the US government losing a bomber carrying nuclear weapons. Back in 1956, a B47 Statojet was lost across the Mediterranean Sea. Nothing from the flight, including crew, debris, or the missiles were ever recovered.
Reports say that the three manning the aircraft were descending into a cloud while trying to refuel for a second time. No one made contact with the tanker. Luckily, the nukes were never a threat to start a nuclear war; as there are plenty of safety precautions to avoid such issues when a plane is going down. The US government has a lost a total of 11 nukes, and two of them that still remain the biggest mystery are from this flight.
Two different aircrafts of the same flight number were involved in accidents in the same year, but this one from USAir back in September 8th, 1994, killed all 132 crew and passengers on board. On a path from Chicago, Illinois, to West Palm Beach, Florida, Flight 427 was making a stop at Pittsburgh. Upon arrival, the crew lost control of the aircraft when it made loud thumps, clicking sounds, and was rolling over. In a span of minutes, the plane nose-dived into Hopewell Township in Beaver County, Pennsylvania, and barely missed a shopping mall.
After a four and a half year investigation from the National Transportation Safety Board, they determined that the probable cause was due to the ” movement of the rudder surface to its blowdown limit“. Essentially, there was a jam in the rudder power control unit that caused the pilots to lose control.