(CNN)Â - The U.S. Navy commander leading the American effort to find Malaysia Airlines Flight 370 said he's "optimistic" about how the search is proceeding.
"We are detecting very continuous pings coming through in a manner consistent with exactly what you'd expect from a black box," Commander William Marks told CNN's Erin Burnett on Friday. "We've ruled out that it was anything natural, or anything from commercial shipping, or anything like that."
Australian Prime Minister Tony Abbott said earlier Friday that search efforts are heading in the right direction. Marks said, "I agree with the prime minister. We're optimistic."
Officials tell CNN there have been no confirmed acoustic detections over the past 24 hours.
That's significant because at most, the black boxes have a couple more days of battery life left in them, according to he largest manufacturer of black box pingers.
The technology that will search underwater for the wreckage - like the Bluefin 21 - is now of even greater importance.
CNN'S Rosa Flores has a demonstration on the underwater technology that will locate the missing wreckage.
It has been 36 days since Malaysian Airlines Flight 370 vanished with 239 people aboard and frustrations are growing after a series of mixed messages from officials investigating the plane's disappearance.
Who's to blame for what some say is a botched investigation?
David Mattingly takes us through the number of false starts and missteps during the search.
Australian Prime Minister Tony Abbott said Friday that officials are confident that the signals they are detecting are from Malaysia Airlines Flight 370's black box.
But 35 days since the aircraft went missing - not single piece of debris have been found.
Could the plane have ditched into the ocean intact?
CNN's Erin Burnett talks to Richard Quest and Aviation Analyst Miles O'Brien about the intact-ditching theory.
Just in case you were ever tempted to park next to a fire hydrant - CNN's Jeanne Moos has a story that will make you think twice.