The search for Malaysia Airlines Boeing 777, which vanished on March 8 with 239 people on board, has narrowed to a 6.2 square mile patch of sea floor about 1,200 miles west of the Australian city of Perth reported Reuters.

The U.S. Navy-owned robotic sub Bluefin-21 was on its ninth mission scanning the largely unmapped stretch of sea bed where pings from a possible "black box" may have been heard.

Authorities said that the search, which has so far been largely unimpeded by weather, may be affected as Tropical Cyclone Jack continued to move south over the ocean.

"Widespread showers are developing with isolated thunderstorms to the north and east south-easterly winds," the Joint Agency Coordination Center said in a statement addressing the weather forecast for the search area.