Missing Jet Search Focuses on Southern Arc

Sources say the Malaysian plane that vanished most likely took a southern route.
3:00 | 03/17/14

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Transcript for Missing Jet Search Focuses on Southern Arc
Let's get right to the breaking news. A brand-new headline as we come on the air. Officials say it was the copilot who said the last words from the cockpit of that Malaysian jumbo jet, 1:19 A.M., saying all right, good night. We know the transponder was turn off two minutes later. They don't know the time the second key communications system was shut down. 26 countries in the massive search effort. The main focus on the southern Indian ocean off the west coast of Australia. Flight 370 could have remained in the air for seven hours. Some parts of the Indian ocean are almost three miles deep. We have David Kerley with us. We have some brand-new clues. Absolutely. This development of the last kr radio coming from the copilot. You have heard about the two a. The two possible lines of the last location of flight 370. This all comes from partial satellite data. Seems strange. One to the north, one to the south. Two sources tell us the southern arc is the one we need to concentrate on. This morning, as it appears someone shut down much of the communication gear, they probably didn't realize that the jet was still pinging off a satellite over the equator every hour. Six in all. They tell distance, not location. Experts were able to use the last ping to plot position points and the spot where the jet would likely run out of fuel. Connect the dots. Because the Earth is round, we get two a. It was most likely on the southern track that the plane went down. Far west of Australia. Australia now coordinating that search area. The Malaysians are redirecting the search to the south but are asking for help from the neighbors to the north. They confirm a 777 could have taken that strange course. Woefr was at the controls knew what they were doing. If you're shutting off those systems intentionally, one reason is to vanish. To make it difficult to find you. Reporter: As ABC news first reported, soon after takeoff, things start happening in the cockpit. Some time after 1:07, the data transmission system is shut off. At 1:19, the last radio signal. The copimt reportedly radioed all right, good fight. Two minutes later, the location transmission beacon is shut pauch moments later, that hard left bank, which we have been told was preprogrammed into the jet's computer. This would take a lot of thought and, um, a lot of preparation to pull this off. Reporter: Finding the jet remains a priority. This morning, the p-8 is in the region. We just learned that high-tech aircraft will fly to Australia today. Two more Australian planes, a total of three sub-hunters will be there. Let's get more on the pilots. They're the focus of the investigators.

This transcript has been automatically generated and may not be 100% accurate.

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