SYDNEY (AP) — Ten ships are searching the ocean surface, while a U.S. Navy robotic submarine is finishing its ninth mission scanning the sea floor of a section of the Indian Ocean for Malaysia Airlines Flight 370.

Today's search by air was grounded because of poor weather related to a tropical cyclone developing to the north.

The center coordinating the search says the robotic sub so far has covered more than 80 percent of the area it's supposed to be searching, and nothing related to the missing plane has been found.