success of flight 370 but we can be certain that we will spare no effort, that we will not rest until we have done everything we humanly can. reporter: the search zone remains vast, about 86,000 square miles of deep sea. i can promise them that we will not give up. reporter: in kuala lumpur, the last scheduled daily briefing is monday. it s unclear how long the search can go on without finding wreckage. but there is a deadline. the pingers on the plane s recorders are required to last 30 days, designed to last 35. key equipment to find them is arriving on board australia s ship the ocean shield but it won t be used until debris is found. the pinger manufacture says that it was due for an overhaul but never returned for the fix.
operations. both vowing to keep looking. but a distinct shift in australia s tone suggests hope the plane may be found may be evaporating. we cannot be certain of ultimate success in the search for mh-370, but we can be certain that we ll share no effort, that we will not rest until we have done everything we humanly can. reporter: the search zone remains vast, about 86,000 square miles of deep sea. i can t promise them that we will not give up. reporter: in kuala lumpur, the last scheduled daily media briefing is monday. it s unclear how long this search can go on without finding wreckage, but there is a deadline. the pingers on the plane s recorders are required to last 30 days, designed to last 35. key equipment to find them is arriving on board australia s ship the ocean shield, but it
everybody who has a stake in this, review what we do next. reporter: you know, you re going to be on this search week after week after week. when we start settling into months, and make no mistake, no matter what happens this will go on months more. he says can this effort be sustained if they can t pinpoint more of an accurate picture of what happened to that flight? most telling me to be a re realistic search for a black box, the search zone has to be a thousand times smaller than now. carol? malaysian authorities still insist the movements were consist end with a deliberate act. someone with experience turned that plane around. as to who uttered last words to air traffic controllers, investigators say they don t know. former faa inspector and tom
airlines flight 370. an australian naval ship departing under the cover of night heading to one of the most remote places on earth. the ocean shield s three-day journey to the search zone in the indian ocean is now under way, but what exactly thisship is going to do once it reaches the area is still unclear. there s a lot of technology on board, technology that could be crucial to finding the missing malaysian airliner flight 370. but the problem is for that technology to work, the search zone needs to be narrowed in. we need to know where roughly the debris is. and with an area the size of poland being scoured right now, those answers don t exist. with each new discovery comes new disappointment. objects pulled from the ocean have no link to the missing airliner. we started off, running on about eight to ten knots and slowly picking up speed. i think by the time he was doing about 15 knots we re still in the channel. reporter: charter boat captain ray ruby tries keeping
square miles a day. so really, if we re searching for a beacon and we re living on borrowed time, i need something that is less than 1,000 square miles. reporter: the search zone is 100 times that. the clock winding down, the search so far has been a frustrating chase of objects spotted from the sky. but when hunted down at sea, the objects turn out to be either fishing equipment or jellyfish. planes touched down again with little news. more than 100 personnel and search planes like that one in the air, 1,000 sailors at sea, those numbers, the prime minister says, will only increase as the search operation intensifies. thank you so much. thank you. reporter: australia s prime minister thanked the search teams working around the clock, saying this is about more than just finding one jet, it s about anyone who flies on a plane. after dramatically moving the