A year on from the tragedy, Minute by Minute: The Titan Sub Disaster produced by ITN Productions for Channel 5 in the UK creates a detailed picture of events leading up to Titan's ill-fated expedition to the Titanic wreck and asks what lessons can be learned. This clip features never-before-heard audio of the banging that kept rescuers’ hopes alive during the search mission as well as expert opinion. Report by Blairm. Like us on Facebook at http://www.facebook.com/itn and follow us on Twitter at http://twitter.com/itn