Bob, as you point out those families waiting to hear what might have happened to that plane. There are theories emerging tonight. ABC picking up the story from there of what might have happened to... See More
Bob, as you point out those families waiting to hear what might have happened to that plane. There are theories emerging tonight. ABC picking up the story from there of what might have happened to 370. Reporter: No radio call or mayday suggesting something happened very quickly to the 11-year-old 777. It never happens. An airplane does not just drop out of the sky. The jet had no major issues. In 2012 its wing tip was damaged on the ground in Singapore when it struck another aircraft. So what happened? Among the possibilities -- catastrophic structural failure. Were there hidden cracks? Failing rivets? Or even the possibility of a bomb, which led to the fuselage breaking up. Catastrophic engine failure on a jet, Boeing says, can fly across an ocean on one engine. Losing two engines, they could have restarted it. Highly unlikely they would lose all electrical power. They have backup system on backup system. This is a really reliable plane. Reporter: Other possibilities that can't be eliminated yet -- cockpit breached by intruders or pilot suicide, which took down an Egypt air flight off nantucket from Massachusetts in 1999, and man and machine interface. Today's modern aircraft are so technically advanced, pilots can sometimes not recognize when there is a problem. This is exactly what happened when air France 447 also disappeared in a storm. Some of its sensors weren't working correctly and the pilots didn't realize they were losing air speed. They stalled the big jetliner, which fell into the atlantic killing all on board. Time is of the essence to recover the black boxes. The batteries last only a month. If the batteries run out we don't have the pinger then we have nothing to guide us where the wreckage might be. Reporter: Years later a mini sub recovered the black boxes. The race is on the way to find the 777 to solve the mystery of ma la shah flight 370. I want to bring in ABC John nance. You heard David report there on the pinging, the block box. How long does the pinging last? 30 days is the guarantee from the manufacturer. On both the cockpit and data flight recorder. It may go longer. But that's what they have got in terms of length of time. Given what we know about where the oil is, what do we know about the water, how deep it is, what does this mean for investigators? It's a little over 600 feet. That means they will be able to find it. That's not a terrible depth of a rough bottom that would make a major problem. They will be able to find this. As you know, it's believed the cockpit had been calling in in the coordinates of the plane. In this day and age with gps and sophisticated satellites why aren't we able to track these planes every moment? There are dark Zones that we don't have radar coverage on. During those times when you're in one of those Zones without active radar you're reporting your own position. Either verbally or electronically. You know with gps where you are but you're on your own to report it. We thank you all. Our team coverage of the midair mystery continues throughout the night and of course, first thing in the morning on "Good morning America."
This transcript has been automatically generated and may not be 100% accurate.