Wednesday sprang new hope as the search for Malaysia Airlines 370 picked up new signals officials hope are locator beacons from the data recorders of the missing airplane.
The signals were first picked up by the Australian ship Ocean Shield on Saturday, but then nothing for three days.
On Tuesday, the signals were picked up again by the ship, meaning four signals in the same swath of sea.
Two Saturday, and two on Tuesday, all within a 17 mile area.
"I believe we are searching in the right area, but we need to visually identify wreckage before we can confirm with certainty that this is the final resting place of MH370," said Air Chief Marshal Angus Houston.
There was some initial concern that the sounds could have been naturally occurring, but once the signals were analyzed after being picked up on Saturday, it was determined they very likely they came from electronic equipment.
"They believe the signals to be consistent with the specification and description of a flight data recorder," Houston said.
"I'm now optimistic. We'll find the aircraft or what's left of the aircraft in the not too distant future."