down as a whole unit as opposed to little pieces since we haven't found debris anywhere in that search area. >> professor stupples, this is nearly three miles underwater. how reliable are the pings and how difficult are they to track back to their source at this tremendous depth? >> well, the ping ger locator tt is being used by "ocean shield" is very close to the ocean floor so it's quite likely that it is able to pick it up if the black box is there. the black box range is probably around 1500 to 2,000 meters, just about a mile to two miles. and the locator that is being put down there is only about a mile away from the possible source of this. so it's very likely, if it is there, it will be picked up. >> david soucie.