MH370: Underwater vessel set to search for missing plane

The hunt for missing Malaysia Airlines flight MH370 could soon head to the ocean floor using an autonomous sonar vessel after possible black box signals were detected, the head of the Australian-led search operation said.A month to the day since the Boeing 777 disappeared, retired Air Chief Marshal Angus Houston warned that hopes of finding surface debris were fading and that sonic "pings" detected by the Australian naval ship Ocean Shield were the best lead.