Search crews looking for Malaysia Airlines Flight 370 set out again Monday morning after efforts Sunday resulted in new debris sightings but no confirmed signs of the passenger jet.

An Australian navy support vessel, which will tow U.S. Navy equipment listening for “pings” from the plane’s black box, was scheduled to depart Perth on Monday. It was to join nine other ships and 10 planes scouring the Indian Ocean for signs of the plane, which vanished March 8. But the exact location of where the plane went down has not been determined.

Time is running out for the search team to locate the black box, a critical piece of equipment containing cockpit audio and flight data. The box will emit signals for about 30 days, which means the operation has only about a week left to find it before it goes silent.

The hunt for Flight 370 stepped into a higher gear Sunday. Nine planes — from Australia, Japan, China, South Korea, the United States and Malaysia — crisscrossed the 198,200-square-mile search area off the coast of Australia. Crews from some of the planes spotted objects floating in the water Sunday. But determining whether that debris is related to the plane will have to wait until ships find the items and scoop them up for examination.

Two ships retrieved objects Saturday, but they were described Sunday by the Australian Maritime Safety Authority as fishing equipment and “other flotsam.” Eight ships were involved in Sunday’s search.

A sophisticated U.S. black box locator is fitted to an Australian navy ship which will depart soon joining the search for missing Malaysian airliner, but time is running out. (Reuters)

On Friday, the operation effectively restarted in a completely different section of the southern Indian Ocean from where it had been focused. The search was moved 680 miles northeast after new analysis by investigators indicated that the aircraft had been traveling faster than previously thought and therefore would have run out of fuel much sooner.

[READ: Flight 370, a mysterious “one-off,” spurs calls to modernize tracking technology]

Meanwhile, 29 Chinese who had family members on the flight arrived Sunday in Kuala Lumpur seeking answers from the Malaysian government about what happened to their loved ones. Two-thirds of the 227 passengers aboard Flight 370 were Chinese, and their relatives have expressed deep frustration with Malaysian authorities since the plane disappeared.

“We have demanded that we meet with the prime minister and the transportation minister,” said Wang Chun­jiang, whose younger brother, Wang Chun­yong, was on Flight 370, the Associated Press reported. “We have questions that we would like to ask them in person.”