The Biggest Mysteries of Missing Malaysian Flight MH370

March 9, 2014 — -- intro: As the search continues for Malaysian Airlines flight MH370, more questions than answers remain about the how the Boeing 777 jetliner could have disappeared.

Since the plane's disappearance early Saturday, revelations about the passenger list and plane's flight plan have left officials scrambling to decipher new complicated clues.

As officials and authorities work to unravel what happened, they remain hampered by the lack of physical evidence including the missing flight data recorder and cockpit voice recorder.

If they can find the wreckage site and especially those two "black boxes" they hope that they will be able to get some answers about how and why the flight disappeared.

Follow All the Breaking News on the Missing Malaysian Airlines Flight

quicklist: 1title: Stolen Passportstext: Perhaps the most troubling mystery surrounding the missing plane is whether two passengers who were travelling on stolen passports played any role in what happened to the jet.

Both an Austrian and Italian passenger were listed on the flight manifest, but neither was actually on the plane. Both had their passports stolen in Thailand.

Officials are now combing through CCTV footage to identify the passengers who used the fake passports. They said that they had the passengers' faces on camera and were working with international agencies to find out who they were.

Additionally two other unnamed passengers have attracted increased scrutiny, but officials didn't say why.

"The issue with the passports we have been in touch with the international agencies at the same time our own intelligence has been activated," acting Malaysian Transport Minister Hishammuddin Hussein said. "We are looking at all possibilities."

Plane's Disappearance is Baffling

Without more information or the missing plane's black boxes, authorities could not confirm or rule out terrorism. Although there is an Interpol database of stolen passports, officials told The Associated Press that no one had checked the database prior to the flight taking off.

quicklist:2title: Disappeared Midflight text: The most dangerous parts of a flight are traditionally the takeoff and landing, but the missing jetliner disappeared about two hours into a six-hour flight, when it should have been cruising safely around 35,000 feet.

A flight falling from cruising altitude is incredibly rare and usually a sign of a catastrophic event.

"It never happens, an airplane does not just drop out of the sky," ABC News aviation consultant Col. Stephen Ganyard said.

Additionally the missing flight was a Boeing 777-200, which is considered a very safe model. That model of plane has been flying commercially for 20 years and only had its first recorded deaths last year after an Asiana Airlines flight crashed, killing three passengers.

"We've seen a recent mishap in San Francisco, the Asiana crash, which involved a triple-seven, but in that case it's pretty clear that that was due to pilot error," Ganyard said.

The Malaysian aircraft is 11 years and 10 months old and did not have any major safety issues. In 2012 its wingtip was damaged after clipping another airplane at an airport.

The last plane to crash at altitude was Air France Flight 447, which crashed during a thunderstorm in the Atlantic Ocean en route from Rio De Janeiro to Paris. That flight, an Airbus A330, was found to have crashed due to a combination of a technical malfunction and pilot error.

quicklist: 3title: No Distress Signaltext: Another alarming element in the missing plane case is that the pilots never sent a distress or mayday signal before disappearing from radar.

If pilots did not even have time to alert air traffic control, experts say that is a likely sign that the event would have been quick and catastrophic.