It’s really unfortunate that certain things happened that caused by airplane crashes or mishaps. Although this is a rarity to go out, it still does happen. Here are 4 mysterious airplane tragedies.

Pan Am Flight 103

In 1988, this flight from Europe to North America ended up in an explosion over Lockerbie, Switzerland. 270 people died on this flight. It was believed that a Libyan intelligence operative was the one behind the crime, but a former Iranian intelligence officer claims it was a hit ordered by Iran as payback for a U.S. strike on an Iranian passenger flight.

TWA Flight 800

230 people were killed in 1996 when this flight crashed just outside of JFK. The probable cause was an explosion of flammable air vapors in the fuel tank that may have been triggered through a short circuit. However, some people said they saw a missile hit the airplane.

EgyptAir Flight 990

In 1999, this flight crashed 60 miles into the ocean off of the coast of Nantucket, Massachusetts. The wreckage was found, and the only theory from the U.S. National Transportation Safety Board was that the crash was due to a distraught pilot. However, the Egyptian Civil Aviation Authority thought otherwise when they believed it a mechanical error.

Air France Flight 447

In 2009, this flight from Rio de Janeiro to Paris crashed into the Atlantic Ocean killed 228 people. It took three years to report that ice caused the autopilot to disengage. 74 bodies are still unaccounted for years later.