MH370 and 5 Other Unsolved Aviation Mysteries

— -- After nearly three years and $150 million dedicated to scouring the bottom of the Indian Ocean, authorities suspended the search today for Malaysia Airlines Flight 370.

The Boeing 777, with 239 people on board, disappeared after inexplicably veering off course on March 8, 2014 — beginning the world's greatest aviation mystery.

A major international effort led by the Australian Transportation Safety Bureau examined more the 45,000 square miles of ocean floor at a painstaking pace.

Only small pieces of debris have been found west of the search area, none of which definitively point to answers in the mystery.

As the search for the jet comes to an end, at least for now, it remains one of many unsolved aviation mysteries that have captivated people all over the world. Here are a few notable events in aviation history that have perplexed both aviation experts and the public.

Amelia Earhart

Various theories swirl around Amelia Earhart's mysterious disappearance over the Pacific Ocean. In her effort to become the first female pilot to circumnavigate the globe, she was low on fuel and struggled to find a landing strip on tiny Howland Island, southwest of Hawaii.

Radio transmissions with a U.S. Coast Guard cutter assigned to assist her approach to Howland Island were unsuccessful. Strong signals from Earhart suggest she was in the immediate area, but on a cloudy day, visibility was limited. Her plane was never found.

Eastern Airlines Flight 980

On New Year's Day 1985, Eastern Airlines Flight 980's Boeing 727 crashed on its approach to La Paz, Bolivia. The airport's runway is at an altitude of 13,000 feet — the highest international airport in the world.

On a cloudy night, with storms in the area, Bolivian air traffic controller cleared the U.S. airliner to descend to 18,000 feet. Unequipped with radar, the controllers didn't know the aircraft was several miles off course and that such a descent would lead it straight into the side of Mount Illimani, killing all 29 people on board.

The cause of the accident was never determined, but many nefarious theories have circulated. The wife of the U.S. ambassador to Paraguay was on board, as were members of a prominent South American family.

At 19,600 ft, the crash site was long considered inaccessible, and an international recovery effort came to a halt. It wasn't until May 2016 that two Bostonians, inspired by a Wikipedia search, ascended the mountain and recovered remains of a flight recorder. After months of a diplomatic impasse, the evidence was finally handed over for examination to the U.S. National Transportation Safety Board on Jan. 4, 2017. The agency has not yet released any findings.

D.B. Cooper

The real identity of D.B. Cooper, or Dan Cooper, remains a mystery after he hijacked a Northwest Orient Airlines plane bound for Seattle in November 1971.

He forced the Boeing 727 to land and demanded $200,000 and a parachute. After authorities met the unidentified man's demands, he ordered the crew to take off and head to Mexico. After takeoff, somewhere between Seattle and Reno, Nevada, the hijacker jumped out of the back of the plane with the parachute and cash. The FBI conducted an investigation, finally suspending the case in July 2016 without ever discovering what happened to the unidentified man.

EgyptAir Flight 990

In October 1999 a Boeing 767 from New York bound for Cairo crashed off the island of Nantucket in Massachusetts. All 217 people on board EgyptAir Flight 990 were killed.

Egyptian authorities pointed to mechanical failure, while a final report from the NTSB said the crash was a result of the first officer's actions, but the reasons for those actions were never determined. The final words from the flight's cockpit voice recorder are the first officer's repeating over and over, "I rely on God."

B-47 Disappearance

In 1956 a Boeing B-47 went missing over the Mediterranean Sea carrying nuclear weapon material.

The three crew members were flying nonstop from MacDill Air Force Base in Florida to Ben Guerir Air Base in Morocco. The flight refueled in air without incident. After descending to make a second refueling effort, the jet lost communication with the fuel tanker. An extensive search turned up no bodies or debris.