Why technology was unsuccessful in finding MH370 which disappeared in 2014, New mission to find MH370 is planned to be launched

Flight MH370 left Kuala Lumpur was bound for Beijing in March 2014 when it disappeared, with 239 people on board. Even after the largest and most expensive search in aviation history, to date, neither any confirmed debris from the aircraft nor any survivors have been found. A four-year deep sea hunt in the southern Indian Ocean off western Australia  costing $200million was conducted but the full aircraft has never been found. The search for Malaysia Airlines Flight 370 ended in January after a deep-sea sonar scan of 120,000 square kilometers (46,000 square miles) of ocean floor southwest of Australia failed to find any trace of the Boeing 777 . But research has continued in an effort to refine a possible new search.