the weekend, new and provocative clues coming in about the mystery of the vanished airplane. Tonight, we're going to zero in on some key questions. New evidence that the plane's communications were... See More
the weekend, new and provocative clues coming in about the mystery of the vanished airplane. Tonight, we're going to zero in on some key questions. New evidence that the plane's communications were deliberately shut off and also tonight, did the plane plummet or swerve as it was trying to fly? And finally D it end up in water? Or on land? ABC's David Kerley, now, with brand-new details on the unfolding mystery. Reporter: Tonight, ABC news has learned not just one turn, but other turns that took the jet airliner toward the Indian ocean, even more evidence suggesting a rogue pilot or a hijacker in control of mh370. That indicates someone may be on the controls. Slight turns, I could see, but, if someone is making many changes, that would be an initial impact on the controls. Reporter: Two communications systems were turned off possibly on purpose. Pilots know how to do this as we were shown today. That transponder which gives the jet's location is controlled just by a switch. It can easily switched off. A data system was also turned off according to our source. But part of that system keeps working. I can't be turned off. Something that pilots around the world didn't know until yesterday, it's a transmitter, still pinging, talking to a satellite every hour, sending a signal that's relied to the ground. The intent for that on top of the aircraft. Reporter: U.s. Officials say that those satellites receive information for four five hours. That could be critical. Because flying five more hours, it could travel 2,400 miles. More than the size of the united States. Those satellite pings could narrow that significantly. If they find the wreckage, it could be deep. Part of the Indian ocean, as many as nine buildings. We talked to neighbors who had nothing bad to say about either bad. The encouraging news those satellite pings could narrow what is now a really massive search area. Thank you so much, David. Let's bring in once again, ABC's aviation military expert, Steve beganyard. Tell me about these twiggss and turns. Conflicting stories tonight. We're seeing heading changes, where the aircraft changes its nose position and moves around the sky. This would confirm as David said in his story, that we are seeing a airplane that's being controlled by pilots or somebody in that aircraft. Let me ask about this report of land or sea, namely they're using, according to the ap, heat-seeking devices in order to examine the islands tonight. They aren't exactly heat-seeking. They're looking at differential. It will allow them to see the contrast between a piece of metal on floating on top of the oelgs and the ocean itself. Give me just your gut sense, where we're heading in this story, what we're going to find sf. It's been an amazing day, it really has, personally my opinion has changed almost an hour, it's going to depend on what that radar data shows. Big changes in altitude up and down, it's probably someone a hijacker. Trying to control that airplane. If the altitude is fairly steady, it's probably pilot and probably deep under the Indian ocean. Thank you once again, Steve ganyard reporting in.
This transcript has been automatically generated and may not be 100% accurate.