Yet another theory is taking shape about what might have happened to missing Malaysia Airlines Flight 370: Maybe it landed in a remote Indian Ocean island chain.
The suggestion -- and it's only that at this point -- is based on analysis of radar data revealed Friday by Reuters suggesting that the plane wasn't just blindly flying northwest from Malaysia. And it's just one of untold theories floating around about what might have happened to the airliner, which disappeared a week ago Friday without leaving much of a trace of where it had gone or why.
Reuters, citing unidentified sources familiar with the investigation, reported that whoever was piloting the vanished jet was following navigational waypoints that would have taken the plane over the Andaman Islands.
The radar data don't show the plane over the Andaman Islands but only on a known route that would take it there, Reuters cited its sources as saying.
The theory builds on earlier revelations by U.S. officials that an automated reporting system on the airliner was pinging satellites for hours after its last reported contact with air traffic controllers. U.S. investigators concluded that the pings didn't come from other planes, leading some investigators to think the plane flew on for hours before truly disappearing.
Taken together, the data point toward speculation in a dark scenario in which someone took the plane for some unknown purpose, perhaps terrorism.
The movie-plot theory seems more complicated and unlikely than one in which the plane -- its flight crew perhaps incapacitated -- simply flew on until it ran out of fuel or faced some other problem. But it's one that law enforcement has to check out, former FBI Assistant Director James Kallstrom said.
"You draw that arc, and you look at countries like Pakistan, you know, and you get into your 'Superman' novels, and you see the plane landing somewhere and (people) repurposing it for some dastardly deed down the road," he told CNN's Jake Tapper on Thursday.
Aviation experts say it's possible, if highly unlikely, that someone could have hijacked and landed the giant Boeing 777 undetected.
The international airport in Port Blair, the regional capital of the Andaman and Nicobar islands, has a runway that is long enough to accommodate a 777, according to publicly available data.
But the region is highly militarized because of its strategic importance to India, Indian officials with knowledge of the operation tell CNN, making it an unlikely target for pirates trying to sneak in an enormous airplane with a wingspan of more than 200 feet.
Denis Giles, editor of the Andaman Chronicle newspaper, says there's just nowhere to land such a big plane in his archipelago without attracting notice.
"There is no chance, no such chance, that any aircraft of this size can come towards Andaman and Nicobar Islands and land," he said.
The Malaysian government said Friday that it can't confirm the report.
And a senior U.S. official offered a conflicting account Thursday, telling CNN that "there is probably a significant likelihood" the plane is on the bottom of the Indian Ocean.
The jetliner, with 239 people on board, disappeared nearly a week ago as it flew between Kuala Lumpur, Malaysia, and Beijing. The flight has turned into one of the biggest mysteries in aviation history, befuddling industry experts and government officials. Authorities still don't know where the plane is or what caused it to vanish.
Suggestions of what happened have ranged from a catastrophic explosion to hijacking to pilot suicide.
Details of the search
Malaysian officials, who are coordinating the search, said Friday that the hunt for the plane was spreading deeper into both the Indian Ocean and the South China Sea.
India has deployed assets from its navy, coast guard and air force to the south Andaman Sea to take part the search, the country's Ministry of Defense said Friday.
Indian search teams are combing large areas of the archipelago. Two aircraft are searching land and coastal areas of the island chain from north to south, an Indian military spokesman said Friday, and two coast guard ships have been diverted to search along the islands' east coast. Indian officials are also including part of the Bay of Bengal in their search, officials said.
As of Friday, 57 ships and 48 aircraft from 13 countries were involved in the search, Hussein said.
China, which said it would be extending its search, said crews have searched more than 27,000 square miles (about 70,000 square kilometers) of the South China Sea without finding anything.
On Friday, the United States sent the destroyer USS Kidd to scout the Indian Ocean as the search expands into that body of water.
"I, like most of the world, really have never seen anything like this," Cmdr. William Marks of the U.S. 7th Fleet said of the scale of the search. "It's pretty incredible."
"It's a completely new game now," he said. "We went from a chess board to a football field."
• "Seafloor event": Chinese researchers say they recorded a "seafloor event" in waters around Malaysia and Vietnam about an hour and a half after the missing plane's last known contact. The event was recorded in a non-seismic region about 116 kilometers (72 miles) northeast of the plane's last confirmed location, the University of Science and Technology of China said.
"Judging from the time and location of the two events, the seafloor event may have been caused by MH370 crashing into the sea," said a statement posted on the university's website.
However, U.S. Geological Survey earthquake scientist Harley Benz said Friday that the event appeared to be consistent with a naturally occurring 2.7-magnitude earthquake.
• Malaysian response: Authorities continued to defend their response to the crash. "A normal investigation becomes narrower with time, I understand, as new information focuses the search," Hishammuddin Hussein, the minister in charge of defense and transportation, said at a news briefing. "But this is not a normal investigation. In this case, the information we have forces us to look further and further afield."
However, Bob Francis, a former National Transportation Safety Board official, is one of several experts who have questioned how Malaysian authorities have handled the situation.