The search for Malaysia Airlines Flight 370 has officials looking at vast areas of the Indian Ocean and Asia, and the U.S. is deploying some of its top technology in the investigation.The U.S. Navy's most advanced airliner -- the Boeing P-8 Poseidon, designed specifically for long-range maritime searches -- is now part of the massive effort to locate the jet, a search that has taken a dramatic shift in recent days.
A satellite hovering more than 20,000 miles over the sea picked up signals from the plane once an hour for at least four hours after it lost contact with air traffic control, CBS News' Jeff Pegues reported. It did not target a specific location, only a wide perimeter almost equal to the size of the United States. But by determining how far the plane could travel before running out of fuel, investigators were able to outline two corridors where it may have flown -- south from Indonesia through the Indian Ocean, or north stretching over 11 countries, from Thailand up to the border of Kazakhstan.
While neither arc is being ruled out, at least five countries along the northern route, including India and Pakistan, say the jet was not detected by radar over their territory.
U.S. officials believe it is more likely the plane traveled south and crashed into the Indian Ocean. Nearly 400 members of the U.S. Navy are searching those waters.
Navy Cmdr. William Marks, aboard the USS Blue Ridge, which controls the teams scouring the region, said, "They're out there 24 hours a day. It is challenging, but that's what we train for."
They are searching for any sign of Flight 370, including victims. A grief counselor and chaplain were flown out to the USS Kidd, to prepare the crew for what they might find.
Still, there has been no sign of debris and crews are left combing waters that, on average, run more than two miles deep.
CBS News contributor and former head of the National Transportation Safety Board Mark Rosenker said, "(It's) very challenging for those who are doing this. Very frustrating for the investigators, very, very disturbing that we didn't have good information early on, and this is not the way to run a very serious aviation accident investigation."
Adding to frustrations is the fact that, even if investigators manage to track down the black box that captures pilots' communication, it reports just two hours of sound before overwriting.
So what does that mean? If the flight remained in the air for seven hours after it lost contact, Pegues reported, it may never be known why the flight changed its course.