The search of the missing plane has been suspended.Reuters

The mystery behind the disappearance of Malaysia Airlines Flight 370 (MH370) almost three years ago might remain a mystery forever as the underwater hunt for the aircraft for over two years turned out to be a futile exercise. The search operation for the plane has been called off, BBC reported.

Read: Frustrated MH370 victim families to hunt for debris in Africa

The Beijing-bound MH370 had disappeared an hour after it took off from Kuala Lumpur airport in March 2014 with 239 people on board.

Search parties from Malaysia, China and Australia have decided to suspend it after covering an area stretching over 120,000 square kilometres of the Indian Ocean. It was reported that only seven pieces out of the 20 debris found were identified to be from the Boeing 777 aircraft. The investigating agencies even could not pinpoint the exact location where the aircraft had mysteriously disappeared.

MH370 will now join the list of mysterious plane crashes that have remained unsolved.

Here is a look at five unsolved airplane mysteries from around the world:

Flight 19 and the Bermuda Triangle

A group of five Grumman TBM Avenger torpedo bombers (Flight 19) of the US Navy mysteriously disappeared over the Bermuda Triangle in December 1945. All 14 pilots were considered dead. And that was not all. The US Navy had deployed Martin PBM Mariner flying boat to search for the missing planes and it, too, had disappeared. The mystery has remained unsolved. Myths have been built around the Bermuda Triangle about it 'gobbling up' airplanes.

Flight 19
Flight 19 AvengersWiki Commons

Egyptair Flight 990

In October 1999, a Boeing 767 EgyptAir Flight 990, flying from Los Angeles International Airport in the US to Cairo International Airport, Egypt, crashed near Nantucket Island, Massachusetts, US, killing 217 people on board.

The Egyptian civil aviation authorities found the crash was caused by mechanical failure of the aircraft's elevator-control system but the American National Transportation Safety Board found it to be a deliberate action by a relief first officer.

According to the data from the cockpit-voice recorder, the pilot was heard saying "I rely on God," in Egyptian Arabic, seven times.

Speculations have ranged from Egyptian terrorists to Mossad to the CIA. The matter, however, remains unsolved to this day.

Amelia Earhart

Amelia Earhart disappeared in 1937 as she was on her solo-round-world-trip on Lockheed Electra. Her last known position was near the Nukumanu Islands near Papua New Guinea, about 1,300 kilometres into the flight.

There are several theories on what could have happened, including the story that Earhart ditched the aircraft at sea as the fuel ran out. The Gardner Island hypothesis presumes that Earhart did not find the island (Howland) where she was to land and went in search of other islands. Another theory says she was captured by Japanese forces and executed on charges of being a spy. Some others say she might have survived the flight and moved to New Jersey, US, and changed her name to Irene Craigmile Bolam.

Airplane mysteries are not complete without the story of Amelia Earhart's disappearance.

Amelia Earhart
Amelia Earhart's Lockheed Model 10 Electra.Wiki Commons/USAF

Air France Flight 447

In June 2009, Air France Flight 447's flight from Rio de Janeiro, Brazil, to Paris, France, crashed, killing all 228 passengers and crew. This was the first time that an Airbus A330's commercial passenger service was involved in crash.

The crash took place in the middle of the Atlantic Ocean, when it was beyond radar cover. It took two years to recover the black boxes, which were found on the ocean bed. The aircraft had battled a thunderstorm but there was no distress signal from the pilots.

It has since emerged that human error was the reason behind the crash as the pilot had slept only an hour before the flight.

BSAA Avro Lancastrian Star Dust

In August 1947, Star Dust, a British South American Airways Avro Lancastrian airliner had crashed into Mount Tupungato in the Argentine Andes.

A search was conducted to trace the plane's remains over a wide area but it was fruitless. It was after 50 years, in 2000, when a new investigation had found the wreckage of the crash. The reason of the crash was found to be bad weather. Before this, several theories did the rounds about the aircraft's fate and they ranged from abduction by the aliens to sabotage to international intrigue. Eleven people, including six passengers and five crew members, were killed.