The Greatest Plane Mysteries

The disappearance of Malaysia Airlines Flight 370 is not the first airborne drama that has raised more questions than answers.

It’s not the first big jet in the past five years to go missing with no distress signal. It’s not the first suspected plane crash that has taken days to turn up any signs of wreckage. And if some past aviation puzzles are any guide, the debate about what happened to the Boeing 777 and its 227 passengers may go on for years or decades after investigators find the aircraft and pinpoint a cause.

Facts about Flight 370 have been scarce ever since the plane left Kuala Lumpur on a red-eye flight to Beijing early Saturday.

The state-of-the-art plane disappeared at cruising altitude — typically, the safest part of the flight — with no distress signals and no emergency beacon to help light rescuers’ way. Three days of searching by planes and ships from multiple countries, including two U.S. Navy destroyers, have found little more than oil slicks and floating debris that turned out to be unrelated to the flight. The probe has also pulled in reports of stolen passports and a mysterious Iranian ticket-buyer, though those may not prove to have anything to do with what happened.

Did the jet disintegrate on its own? Did a bomb blow it up? Was it hijacked? For now, the answers are lost at sea.

Here are some of the biggest past mysteries involving plane crashes and disappearances:

1. Air France Flight 447 (2009)

If the Malaysian jet has crashed, this incident could be most similar to a deadly 2009 accident involving an Air France Airbus A330 that disappeared over the Atlantic en route from Rio de Janeiro to Paris.

As with the Malaysia Airlines flight, the Air France pilots issued no distress call. Investigators found nothing more about the plane or the 228 people on board for five days, when search-and-rescue teams finally found some of the tail section in the water.

But the wreckage of the plane itself wasn’t found at the bottom of the sea for nearly two years, and it took yet another year for investigators to figure out the cause of the crash — ice crystals that had blocked the plane’s airspeed sensors, leading to a deadly stall.

2. TWA Flight 800 (1996)

The Boeing 747 was bound for Europe when it exploded and crashed shortly after taking off from JFK International Airport, killing all 230 people on board. After a four-year investigation, the National Transportation Safety Board found that the probable cause was a fuel tank explosion sparked by faulty wiring.

But abundant conspiracy theories remain that the cause was something more nefarious, such as a bomb or shoulder-launched missile, even spawning a documentary that came out last year. The NTSB felt compelled to hold a media briefing last summer on the nearly-two-decade-old crash, emphasizing that no radar evidence, physical remains or witness testimony was consistent with a missile strike.

3. EgyptAir Flight 990 (1999)

The Boeing 767 en route from New York City to Cairo crashed shortly after takeoff, killing all 200 people on board. After a two-year investigation, the NTSB concluded that the relief first officer in the cockpit had deliberately caused the crash.

The evidence included the trajectory of the plane, as well as cockpit voice and data indicating that the captain and first officer had fought for control of the plane in its last moments, as the first officer repeatedly said, “I rely on God.” But the Egyptian government disputed that version of events, releasing its own report concluding that the crash was caused by a mechanical failure of the plane’s elevator control system.