6 Mysterious airline tragedies that stumped experts for years

Here are six of the most recent mysterious plane disasters. Some remain unsolved, decades later.

6. March 2014, Malaysia Airlines MH370

Japanese Defense officials at RAAF Base Pearce, before Japan's final search flight for the missing Malaysia Airlines flight MH370 on April 28, 2014. Photo by Emily Wang / AP.

Endless theories are swirling about what became of Flight MH370. To date, the flight still hasn't been found. Was it hijacked or did one of the pilots simply decide to end it all? The latest news suggests the flight veered away from its path and could have disappeared somewhere en route towards India. To this date the mystery remains.

5. 2009, Air France Flight 447

Workers recovering the flight data recorder from the 2009 Air France flight that went down in the mid-Atlantic. Photo by Johann Peshel / AP.

An Air France Flight from Rio to Paris crashed into the Atlantic Ocean in 2009. 228 passengers and crew were killed. For five days, the world waited for the mystery to unravel. Eventually, the search-and-rescue team found the wreckage. It took another three years for a report to reveal the cause of the accident: ice had caused the autopilot to disengage. To this day, 74 bodies still remain unaccounted for.

4. 1999, EgyptAir Flight 990

Police stand guard shortly after victim's family members viewed the remains of EgyptAir flight 990 at a hanger at Quonset Point in North Kingstown, R.I. Photo by Charles Krupa / AP.

Cairo-bound Flight 990 crashed 60-miles into the ocean off the coast of Nantucket, Massachusetts. 217 passengers were killed. The wreckage was found, but the mystery remains. A U.S. National Transportation Safety Board reported that the crash was caused by a distraught pilot. The Egyptian Civil Aviation Authority disagreed and claimed that the crash was due to mechanical error.

3. 1988, Pan Am Flight 103

A salvage crane begins the removal of the nose section of the Pan Am Boeing 747 airliner near Lockerbie, Scotland, Dec. 29, 1988. Photo by Peter Kemp / AP.

Pan Am Flight 103 was flying from Europe to North America when it mysteriously exploded over Lockerbie Scotland. 243 passengers, 16 crew members, and 11 people on the ground were killed. Eventually investigators would discover a bomb caused the explosion. The question, who planted it. A Libyan intelligence operative was convicted of the crime. However, in March 2014, a former Iranian intelligence officer claimed that the bombing was ordered by Iran in retaliation for a U.S. strike on an Iranian passenger flight.

2. 1996, TWA Flight 800

TWA Flight Attendant, Joanne Brody touches the names of several of her fellow employees and friends inscribed on the TWA Flight 800 memorial wall at Smith Point County Park, NY. Photo by Kathy Kmonicek / AP.

230 people were killed when TWA Flight 800 crashed just outside of JFK. A report four years later suggested that the accident was probably caused by an explosion of flammable air vapors in the fuel tank ignited by a short circuit. But the crash investigation was clouded in mystery when several witnesses came forward claiming they saw a missile hit the plane.

1.Flight 191 Mystery

National Transportation Safety Board workers examine the engine that fell off 1979's American Airline's Flight 101 DC-10. Chicago, Ill., May 26, 1979. Photo by Fred Jewell / AP.

The flight number "191" has been associated with numerous crashes and incidents over the years. It has even prompted some airlines to discontinue the use of this number. In 1979, American Airlines Flight 191 went down between Chicago and Los Angeles. In 1985, Delta Air Lines Flight 191 crashed at Dallas-Fort Worth International Airport. In 2006, Comair Flight 5191 crashed in Lexington, Kentucky. In 2012, passengers aboard Jet Blue Flight 191 avoided disaster by subduing the captain who was having a panic attack.