Time to try this again.
The first attempt to use a U.S. Navy underwater vehicle in the hunt for missing Malaysia Airlines Flight 370 ended early, after the probe got close to waters deeper than it is rated to go, setting off safety protocols that sent it swimming back to the surface.
The Navy's Bluefin-21 autonomous underwater vehicle didn't find anything of interest in that first deployment, which a source said lasted less than eight hours. It had been expected to be underwater for 20 hours, but returned to the surface as soon as it dropped to its 4,500-meter maximum, officials said.
Crews planned to move to a shallower area and try again Tuesday, weather permitting.
The aborted mission doesn't indicate anything wrong with the probe, which is designed to fly about 30 meters (100 feet) above the ocean floor and use sound waves to draw a three-dimensional map of what lies below.
"The vehicle's tracking the floor, so when the floor dives, so does the vehicle. And the vehicle goes, 'Uh oh, I'm not supposed to be here' and punches up," said David Gallo, director of special projects at the Woods Hole Oceanographic Institution.
And while it's disappointing the vehicle returned to the surface early, it's not unusual , said David Kelly, CEO of Bluefin Robotics, the company that makes the Bluefin-21.
"We've operated these vehicles around the globe. It's not unusual to get into areas where the charts aren't accurate or you lack information," he said.
U.S. Navy Capt. Mark Mathews of the Bluefin search team said the initial launch Monday night took place "in the very far corner of the area it's searching, so they are just shifting the search box a little bit away from that deep water and proceeding with the search."
It is unclear how much of the area -- 5 kilometers by 8 kilometers (3 miles by 5 miles) -- the Bluefin scanned during its first attempt. It could take up to two months to scan the entire search area.
The aborted mission is the latest glitch in a 39-day search for the missing jetliner, which vanished March 8 with 239 passengers and crew on board after taking off from Kuala Lumpur, Malaysia, bound for Beijing.
Surface and satellite searches have turned up nothing conclusive -- and confusing, sometimes conflicting details from investigators have muddied the public image of the search and angered relatives of the missing.
On Tuesday, the Malaysian Cabinet agreed to set up an international investigation to look into the plane's disappearance. Teams will look at the plane's airworthiness, operational issues and human factors that may have played a role, officials said.
Malaysia's acting Transportation Minister Hishammuddin Hussein also said Tuesday that if searchers are able to recover the plane's vital black boxes, it matters less which country takes control of them than does "finding out the truth."
The co-pilot's cell phone
Meanwhile, a new detail emerged from the flight on Monday.
A U.S. official told CNN on Monday that co-pilot Fariq Abdul Hamid's cell phone was on and made contact with a cell tower in Malaysia about the time the plane disappeared from radar.
However, the U.S. official -- who cited information shared by Malaysian investigators -- said there was no evidence Fariq had tried to make a call.
The official told CNN's Pamela Brown on Monday that a cell phone tower in Penang, Malaysia -- about 250 miles from where the flight's transponder last sent a signal -- detected the first officer's phone searching for service roughly 30 minutes after authorities believe the plane made a sharp turn westward.
The details do appear to reaffirm suggestions, based on radar and satellite data, that the plane was off course and was probably flying low enough to obtain a signal from a cell tower, the U.S. official said.
U.S. officials familiar with the investigation told CNN they have been told that no other cell phones were picked up by the Penang tower.
Pilots are supposed to turn off their cell phones before pushing back from the gate.
When the plane first went missing, authorities said millions of cell phone records were searched, looking for evidence that calls had been made from the plane after it took off, but the search turned up nothing.
The suspected oil slick
Another possible clue into the plane's disappearance appeared Monday.
Australian officials announced the Australian ship Ocean Shield had detected an oil slick Sunday evening. It is unclear where the oil came from; a 2-liter sample has been collected for examination, and was on its way Tuesday to western Australia for analysis. Test results could be days away.
CNN aviation analyst Les Abend, who flies a Boeing 777, said the engines on the plane have about 20 quarts of oil each.
"It could be slowly dripping up to the surface," he told CNN's "Anderson Cooper 360." "They're saying an oil slick. I'm wondering if it's just some sort of a fluid slick. It could be (from) hydraulics."
If it is oil, it's not the first oil slick detected as part of the search.
A similar find in the first days of the search was determined to be fuel oil from a freighter.
Surface search nearing end
While air and sea surface searches continued Tuesday some 2,170 kilometers (1,350 miles) west of Perth, Australia, those searches are likely nearing an end.
"The air and surface search for floating material will be completed in the next two to three days in the area where the aircraft most likely entered the water," retired Australian Air Chief Marshal Angus Houston, head of the country's Joint Agency Coordination Centre, said Monday.
With no debris found after weeks of searches and no possible pings from the plane's black boxes detected in a week, Houston said it was time to focus the search underwater.