they have taken a sample to be analyzed. here s what he said. ocean shield detected an oil slick yesterday evening in our current search area. a sample of about 2 liters has been collected, and it will be a number of days before it can be landed ashore and conclusively tested. i stress, the source of the oil is yet to be determined, but the oil slick is approximately 5,500 meters down wind and down sea from the vicinity of the detections picked up by the towed pinger locator on the ocean shield. reporter: urging caution, too, angus houston there saying we don t know what that is, we re checking it out, that oil slick. one other point to come out. you know, we ve been talking about the dozen planes and a dozen ships that daily are out there searching a few hundred miles to the west looking for any debris that might have been carried there by the current.
now, after that was done, that enabled the deployment of the pinger locator. and she went into that area and received transmission rz from the deep. that is the basis, the four transmissions taken together are the basis for the underwater search area. what more do we know about the terrain down there? is it flat? this is an area that is new to man. we have a great asset in the ocean of rapid vessel hms echo. that is a state of the art aircraft with equipment that can assist in mapping the ocean
that builds pingers say that the batteries are most likely dead or close to it. will ripley is following every step of the search in perth. will, why did they expand this visual search area? reporter: well, because they are continuing to fly out every day and they still haven t found a piece of debris. they are constantly looking at the data, at the currents and they are trying to get a handle on where this debris field, if there is still debris floating, where it could be. they continue to search tirelessly. not only above the surface but under water as well to see if there are any pings left from the black box. the pings are getting weaker each time the pinger locator was able to lock on to them. this could be a key week for the search, fred, because at some
reporter: we went behind the scenes at phoenix international, the company that made the towed pinger locator. among them, sonar techs tasked with looking at monitors and listening and listening some more. you ll sit for days at a time and then you might hear a chiropractor but you won t hear another one. until you can duplicate it and run it back at different angles, only until then are you positive that you have it. reporter: and even then, experts say sound in the ocean can play so many tricks on your ears. several people can look at a signal and see different things. because all they are recording is sound energy. reporter: false positives from research equipment left in the area, from the vessel itself can also play tricks on the techs: they are good at weeding out false positives. they do it by monitoring the repetition rate and in op centers like this one on board,
point and i can guarantee you, there are conversations happening behind the scenes right now. they are going to have to make the decision that there is not anything to hear. we need to start getting down there and looking. this is they have narrowed down as much as is going to happen using the pinger locator and then they get the submersible down there to see what they can find. it sounds like the searchers are in concert with what some of the developers of the company that actually builds pingers that the batteries are likely dead so they are not likely to hear anything more at this point? reporter: you know, not anything publicly yet. that hasn t actually been confirmed by the search chief angus houston. whenever he has something significant to aunited statesnn calls for a press conference. as far as we know, nothing new has been found. nothing new has been heard. the next time he calls that press conference, fred, is going to be announce that something has been found or to a