A Vietnam Air Force search and rescue aircraft An-26 takes off on a mission to find the Malaysia Airlines flight MH370 that disappeared from radar screens in the early hours of Saturday, at a military airport in Vietnam's Ho Chi Minh City March 10, 2014. The disappearance of the Boeing 777-200ER jetliner is an "unprecedented mystery", the country's civil aviation chief said on Monday, as a massive air and sea search now in its third day failed to find any trace of the plane or 239 people on board. REUTERS/Kham (VIETNAM - Tags: DISASTER TRANSPORT MILITARY)