How can a passenger jet just disappear?
That's what many people are asking Monday after Malaysia Airlines Flight 370 vanished three days earlier. The families of the 239 people on board, who were on their way from Kuala Lumpur, Malaysia, to Beijing, China, have been told to prepare for the worst.
There have been reports of oil slicks and debris in the waters of the South China Sea, but none of it has matched the missing plane.
It's certainly not the first time a flight has met a mysterious end. Here's what happened to some other planes that disappeared or crashed amid strange circumstances:
1937: Amelia Earhart disappears during round-the-world flight
It was her final challenge and one she wanted to undertake as she neared her 40th birthday: become the first woman to fly around the world. On July 2, Earhart took off with her navigator. The pair vanished over the Pacific Ocean. The United States gave up looking for the plane after spending millions of dollars to search hundreds of thousands of miles of ocean.
1945: The legend of the Bermuda Triangle is born
Flight 19 was supposed to be a routine training exercise for five U.S. military torpedo bombers. The men completed their task with no problems and then, 90 minutes after taking off to head back to Ft. Lauderdale, the squadron commander reported that he was lost. Over the next three hours, the men were taken off-track and far out to sea, where it is believed they lost fuel and eventually crashed. This area -- a cone-shaped vicinity extending northward from Puerto Rico to about halfway up the U.S. Eastern Seaboard -- became infamously known as the "Bermuda Triangle."
1957: "Romance of the Skies" crashes over the Pacific
The Boeing 377 was en route from San Francisco to Honolulu -- the first leg of a round-the-world journey -- when it crashed. All of the 44 people on board were killed. Investigators found "no probable cause" for the crash, but did find elevated levels of carbon monoxide in several of the recovered bodies.
1979: American Airlines Flight 191 falls out of the sky
American Airlines Flight 191 was bound for Los Angeles when it took off from Chicago O'Hare International Airport. Less than a mile from the runway, the DC-10 jet fell out of the sky, killing all 271 people on board and an additional two people on the ground. The National Transportation Safety Board (NTSB) determined that shoddy maintenance eventually allowed for an engine to tear loose during takeoff and damage other vital systems on the aircraft.
1983: Korean Airlines 007 goes off track
The 747 was en route from the United States to Seoul, South Korea, when it drifted off course and headed for Soviet territory. The plane, which was carrying 61 Americans, including Rep. Larry McDonald of Georgia, had been set on autopilot. But what pilots didn't know is that the autopilot had been set to fail as a result of what pilots now believe may have been pilot error. After deviating more than 200 miles off course, Soviet pilots shot down the airliner, killing 269 innocent people. It wasn't until nearly a decade later, when the Cold War ended, that Russia released a transcript of the cockpit voice recorder, which detailed the truth.
1996: Conspiracies swirl after TWA Flight 800 crashes
The Boeing 747 was bound for Paris when it crashed into the Atlantic shortly after taking off from New York. All 230 people on board died in the explosion. The NTSB later blamed the blast on an electrical short circuit that found its way into the center wing fuel tank. Witnesses, however, say they saw something shoot up toward the plane before it crashed. But investigators have continued to stick to their findings, insisting even last year that a missile did not take down the jumbo jet.
1999: Learjet flies out of control
Former PGA champion Payne Stewart was one of six who died on board his Learjet when it crashed into South Dakota farmland. The plane was intercepted by several other aircraft before it spiraled down to the ground. Pilots who observed the Learjet in the air said the front windshields seemed to be covered with frost or condensation. The NTSB ultimately determined that the cabin lost pressurization for "undetermined reasons," causing crew members (and the others) to become incapacitated from lack of oxygen.
1999: Officials point the finger at a pilot
All 217 on board a Boeing 767 were killed when the plane, which was on its way from New York to Cairo, Egypt, crashed into the Atlantic Ocean. The NTSB concluded that a pilot intentionally downed EgyptAir flight 990. Investigators said any possible mechanical failure was inconsistent with the downward trajectory of the plane. The cockpit voice recorder also captured the pilot sounding unsurprised when the plane started to go down and he kept saying "I rely on God" as they crashed. Egyptian officials, however, have pointed to supposed mechanical failures.
2009: It takes years to finally get an answer
Air France Flight 447 was en route from Brazil to France when it plunged into the Atlantic Ocean, killing all 228 people on board. It took four searches over two years to find the bulk of the wreckage and the majority of the bodies, which were hidden in a mountain range deep under the ocean. French officials released a final report on the disaster in 2012, which blamed the crash on errors by pilots who failed to react effectively to technical problems. Ice crystals had blocked the plane's pitot tubes, which are used to determine air speed, according to the report. When the autopilot disconnected, the pilots didn't know how to respond, according to officials.