Underwater signals were detected anew on Thursday in the search for Malaysia Airlines flight 370, in the same area where previous signals have been detected.

An Australian navy vessel has been patrolling the area heavily in recent days and has picked up five different sounds that are consistent with black box signals. The search has been focused on Australia’s west coast.

“The acoustic data will require further analysis overnight,” search leader Angus Houston said in a statement.

There have been several listening devices dropped into the water in an effort to pinpoint where the signals are coming from, because the search area is roughly the size of Los Angeles. However, Houston says he feels that the wreckage will be found soon and that they are on the right track. He can’t confirm with surety that the area is in fact the crash site, though.

“I’m now optimistic that we will find the aircraft, or what is left of the aircraft, in the not too distant future – but we haven’t found it yet, because this is a very challenging business,” Houston said. “I think that we’re looking in the right area, but I’m not prepared to say – to confirm – anything until such time as somebody lays eyes on the wreckage.”

Flight 370 disappeared on March 8 during a trip from Kuala Lumpur, Malaysia, to Beijing with 239 people on board. Speculation about what might have happened to the jet–and why it seemed to move off course just before the last ground communication–has run rampant, but few answers have come forth. As far as Houston is concerned, the search is made even more difficult by the fact that the bottom of the Indian Ocean is covered in a thick layer of silt which could suck under anything which lands on the bottom. Also, the black box–if that’s what is sending out the sounds heard underwater–has a battery that could be dying.

“So we need to, as we say in Australia, ‘make hay while the sun shines,”‘ Houston said.

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