The underwater search for any sign of Malaysia Airlines Flight 370's black boxes began Friday, just days before the devices' batteries are expected to die.
And Chinese officials say a patrol ship detected a pulse signal in southern Indian Ocean waters Saturday, this according to state news agency Xinhua.
But as experts warned CNN, it's still unclear if the signal is coming from the missing Malaysia Airlines plane. It's also possible the that pulses are a false signal.
Until the data from the Chinese patrol ship is confirmed, other ships are continuing to comb the rest of the search area for signs of Flight 370's black boxes. (Via ITN)
"Right now, two ships are towing unmanned submersibles that scour the ocean floor and listen for pings emitted from the flight data recorders." (Via Al Jazeera)
"They're towing this flight locator, or this locator as it's called, underwater. It can go as much as 9 to 10,000 feet underwater apparently." (Via Fox News)
The search for the missing jet has been a race against the clock for weeks now.
Authorities have been desperately searching for wreckage in the south Indian Ocean that will help searchers determine where to listen for pings from the plane's black box recorders. (Via BBC)
Those black boxes are extremely valuable in locating the jet and helping investigators determine what exactly happened the night Flight 370 disappeared.
"Black boxes are about the size of a shoe box and have the cockpit voice recorder and the flight data recorder, with information on things like the plane's speed, and position." (Via CBC)
As The Wall Street Journal points out, black boxes aren't actually black — they're bright orange recording devices that can help investigators determine how or why a plane crashed.
The devices include an underwater locating beacon, which automatically actives on contact with water and has a 30-day lifespan. (Via Wikimedia Commons / NTSB)
But the Boeing 777 has been missing for four weeks now, and experts estimate that beacon could fall silent as soon as Monday, if the batteries aren't already dead. (Via Sky News)
But determining whether the black boxes' batteries are still working could be tricky for searchers.
"Going over an area and not hearing the pinger doesn't mean that the aircraft is not there. The TPL is useful if you do hear something. If you don't hear something, not that useful." (Via CNN)
If the two ships with pinger locators on board can't find any trace of the black boxes, sonar and radar devices will be used next in the search.