>> michael mccarthy was on the team that found the sidney, after more than 25 years of searching. he sees eerie similarities in the search for flight 370. >> you have an enormous area where it could be or may not be. you have the similar depth of water. you have similar emotions. >> but the search today has the advantage of technology. if satellite images and search planes can find debris from the plane in time, the flight data recorder should be sending out a signal. but the search for hmas sidney shows that even without that signal wrecks can still be found using sonar scans. it just takes time. mccarthy describes the process. >> that just mows the lawn back and forward until you finally find a signal which tells you there, we have our rig. and that takes a while even if you know where you're going to go. >> by salvaging the sidney,