With each passing hour, the mystery surrounding the disappearance and presumed loss of Malaysia Airlines Flight 370 gets more strange…and speculation is rampant.

The Vietnamese Navy is reporting that the plane crashed off Tho Chu Island in the South China Sea between Vietnam and Malaysia. The flight, carrying 239 passengers—including two infants and 12 crew members—departed Kuala Lumpur at 12:41 am, local time, bound for Beijing. The aircraft was scheduled to land at Beijing International Airport at 6:30 am, local time.

I must preface all of this by saying that speculation is dangerous while trying to establish the probable cause of the disappearance and presumed crash of the Malaysia Airline Boeing 777. But, with each passing hour, certain things can be ruled out:

1. Weather. There were no reports of severe weather in the area
2. No terrorist group has claimed responsibility for the loss of the plane
3. No widespread debris field has yet been found.
4. Nothing has emerged about the mechanical history of this particular tail number—no past history of structural or pressurization problems.

Numbers three and four are particularly interesting. Had the plane suffered a severe structural/pressurization failure at cruising altitude (had it broken apart), there would have likely been a widespread debris field (much like Pan Am Flight 103 over Lockerbie Scotland in 1988). So far, none has been discovered.

Yet, a highly rare, catastrophic breakup at altitude could possibly explain why the cockpit crew was unable to broadcast any sort of an emergency.

Modern jet aircraft do not suddenly fall out of the sky. As any air accident investigator can tell you, no plane ever crashes for any one reason. It’s two, perhaps three reasons—occurring either in short order or simultaneously.

But, this much is known: There has been no sighting of a widespread debris field. That is the most curious thing for investigators. There was no radio transmission or emergency broadcast from the plane before it disappeared, which raises some very interesting questions. If the plane suffered a sudden and catastrophic fuselage or pressurization problem at altitude, it would have broken up in the air, and the debris field would be massive. (As in Pan Am 103). It also would then explain why there was no radio call or other emergency transmission made from the crew.

But planes don’t just fall from the sky. No one factor causes this. It’s a combination of two, or three things that — in concert — create a situation where the pilots cannot recover. But what were the factors here? There is tons of speculation, which can be dangerous, but investigators systematically must rule things out before they can ever rule anything in.

While it is very early in the investigation, this is what they are beginning to discount: weather issues. That’s it. Every other theory is still in play.

In the meantime, Boeing and Malaysia Air are both now poring over the entire service records of this particular 777 to see if there was any prior mechanical issues or a problem with air pacs or pressurization.

But, the real focus right now (in addition to pursuing the “fake passport” report), is leading investigators directly to the area of cockpit crew “human factors.”  One of the things investigators in Malaysia are looking at intensely are the backgrounds of both the pilot, the copilot, and the relief pilot on that flight. What were the dynamics of their personal lives? There have been previous incidents with other airline crashes where one of the pilots wanted to kill himself. He waited until the other pilot left the cockpit to go to the lavatory, then locked him out and pushed the yoke all the way down. In less than three minutes, the plane impacted the ground at around 400 mph (or in this case, the sea). Again, the reason why investigators are so interested in this theory is the total lack of communication from the plane prior to impact.

Of course, there is nothing definitive or concrete yet, as there were no signals received from the plane’s ELT (emergency locator transmitter), which normally has a battery life of 48 hours.

We will continue to monitor events. But I want to caution everyone that in order to arrive at a probable cause of what really happened, the investigators have to continue to rule out many possibilities before they can ever rule in anything.

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By Peter Greenberg for PeterGreenberg.com