• The word that can’t be mentioned in the MH370 probe
· Where in the world is MH370?

The search for Malaysian Airlines Flight 370 deepened on Tuesday with the announcement that Australia will now head the mission in the Indian Ocean to recover the missing Boeing 777, committing more maritime resources to the case.

As investigators carry out searches of the homes of the two pilots, reports suggest the plane may have flown under the radar (a technique known to pilots as “terrain masking”) for over seven hours after changing its flight course.

With the hunt entering its 10th day, public suspicions surrounding Captain Zaharie Ahmad Shah are intensifying as his political and religious views are called into question and reports suggest that his wife and two children moved out of their home the day before the plane took off. 

Every new piece of information about the ill-fated flight is devoured by a hungry public desperate for answers, but history tells us we may never get the full story of what happened to the 239 people on board.

Before MH370, there were several mid-air disasters that, to this day, remain enigmas. Here’s why.

1978: The curious case of Frederick Valentich

A single-engine Cessna plane, similar to the one Frederick Valentich was flying when he disappeared. Photo: Shutterstock

It should have been a simple training flight for 20 year-old pilot Frederick Valentich when he set out for Tasmania’s King Island from Moorabbin Airport in Melbourne. Valentich, an aviation enthusiast with around 150 hours of flying experience, contacted the Melbourne Flight Service Unit around 7.00pm on October 21, 1978, reporting the approach of an unidentified large aircraft towards his single-engine Cessna.

Valentich told the control tower that the craft had four bright lights and was orbiting above him. When officials insisted there was no known aircraft in the area, Valentich told them “it’s not an aircraft”, saying the strange vehicle was “playing some sort of game”.

Radio transmission from Valentich cut out minutes later and he disappeared without a trace. The Cessna was never found. Following the incident, several people came forward to report seeing a UFO on the night, but evidence was dismissed.

Ah, Melbourne, that strange aircraft is hovering on top of me again . . . it is hovering and it’s not an aircraft.

Investigators believed that Valentich, who was described by the media at the time as a “flying saucer enthusiast”, merely became disoriented and saw the lights of his own plane being reflected back at him. Valentich’s father insisted that his son was “not the kind of person to make up stories”, arguing that the lack of remains suggested elements of the supernatural.

All we have today is the chilling transcript of a confused Valentich’s final dealings with Melbourne’s Flight Service Unit.

2003: The apparent theft of a Boeing 727

During what was supposed to be a routine maintenance check on a fuel-carrying Boeing 727 on an Angola airstrip, the plane began taxiing down the runway, taking off without clearance.

On board was American engineer Ben Charles Padilla, a private pilot with no commercial license. Both the headlights and transponders of the plane were turned off before takeoff. Ignoring calls from air traffic control, the plane headed towards the Atlantic Ocean before vanishing.

Initially, the White House feared the plane would be used by terrorists after Padilla’s family speculated that he was kidnapped and held against his will. However, the plane has never resurfaced.

1981: The disappearance of five Aussies and a plane

On August 9, 1981, a light aircraft carrying five Sydney men lost radio and radar contact during a flight from Queensland to Sydney. Unruly weather conditions had caused problems for the single-engine Cessna, with 52 year-old pilot Michael Hutchins telling air traffic control over radio that the plane was being buffeted by winds, “picking up ice” and losing “a hell of a lot” of altitude.

The thicket of NSW’s Barrington Tops forest, above which a flight carrying five men disappeared in 1981. Photo: Shutterstock

After control warned Hutchins that his lowest possible safe altitude above the area was 6000 feet, he simply replied “Five thousand …” before dropping from the radar.

The plane disappeared over Barrington Tops, a thick, impenetrable section of forest northwest of Newcastle. Some 33 years later and the wreckage has never been uncovered. Yvonne Pembroke, the wife of passenger Philip Pembroke, told The Age that she would still like to solve the mystery of her husband’s death.

“All that would be left would be the teeth,” Mrs Pembroke said. “Half of me says rest in peace there. The other half would really like to know where it landed.”

1996: The strange explosion of TWA Flight 800

The mid-air explosion of this Trans World Airlines flight near Long Island, New York, has been the topic of many a conspiracy theory since its July 17 demise killed 230 people. The plane exploded only 12 minutes after leaving New York’s JFK Airport on a flight to Rome via Paris.

Wreckage from Trans World Airlines Flight 800 floats in the Atlantic Ocean. Photo: Getty

After a four-year investigation, the US National Transportation Safety Board determined the cause of the explosion to be fuel tank fire caused by defective wiring. However, many still believe this explanation to be a government cover-up.

One of the more popular theories was that a rogue missile had shot down the plane. Eyewitness reports of the incident documented seeing a streak of light followed by an eruption of flame, suggesting external detonation. The FBI vehemently denied the possibility of military or terrorist activity being involved in the case.

1957: The inexplicable fate of Pan American Airways Flight 7

Flying from San Francisco to Honololu on November 9, 1957, as part of a round-the-world trip, Pan Am Flight 7 suddenly went down in the Pacific Ocean, miles off its intended flight course. Pilots issued no distress calls.

An extensive search party was assembled and debris and bodies were eventually discovered on November 14.

The 44 people aboard were killed, but only 19 bodies were recovered, all of them exhibiting an elevated level of carbon monoxide in their systems, suggesting poisoning could have been the cause of the crash.

A few passengers were strong candidates for foul play, including a suicidal man who reportedly showed blasting powder to a relative before the flight, and an ex-Navy diver who mysteriously purchased large insurance policies two days before boarding. Flight recordings were never found and no definitive cause of death exists to this day.