A group of divers prepares their gear on the deck of the Search and Rescue (SAR) ship KN Purworejo during a search operation for passengers onboard AirAsia Flight QZ8501 in the Java Sea January 4, 2015.

Indonesian navy divers resumed search efforts on Monday to identify whether the suspected wreckage was in fact part of missing AirAsia flight QZ8501, Reuters news agency reported.

While no signals have been detected from black box recorders, ships and aircraft on the lookout for debris and bodies from the doomed flight widened their search area. Helicopters will search coastal areas

“The weather is quite conducive. The visibility is six kilometers, there’s no low cloud, the wind is calm,” Air Force Lt Col Jhonson Supriadi said.

“With our calculations of currents this strong, every day this operational area is extended,” he told Reuters.

Both flight recorders are located near the tail of the Airbus, but it was unclear whether that part of the aircraft was among the debris found on the seabed.

Indonesia’s meteorological agency has said seasonal tropical storms probably contributed to the Dec. 28 crash and the weather has persistently hampered efforts to recover bodies and find the cockpit voice and flight data recorders that should explain why the plane crashed into the sea.

The main focus of the search is about 90 nautical miles off the coast of Borneo island, where five large objects believed to be parts of the plane – the largest about 18 meters long – have been pinpointed in shallow waters by ships using sonar.

Peter Marosszeky, a senior aviation research fellow at the University of New South Wales in Sydney, said the weather was squarely to blame for the delay in finding the black box recorders, which are designed to emit pings that can be detected by sonar for a month after a crash.

“The seas haven’t been very friendly, but the black boxes have a 30-day life and they will be able to find them, particularly in the shallow waters,” he said.

“It’s the weather that is causing the delay.”

Second AirAsia incident ‘not engine-related’

Separately, AirAsia downplayed Sunday an incident that saw one of its planes turned back before takeoff in Indonesia, Agence France-Presse reported.

Indonesia AirAsia flight 7633 was taxiing in preparation for takeoff Saturday at Surabaya airport when a power unit used to start the plane shut down, an airline official said.

As a result, the pilot turned back to the gate, Raden Achmad Sadikin, director of Safety and Security at Indonesia AirAsia, told reporters.

Local media in Indonesia and Malaysia had reported the Bandung-bound plane’s engine had cut out after emitting a loud bang that terrified passengers, but AirAsia stressed it was a minor incident.

“It’s not that the engine failed. The plane wanted to take off but the APU (auxiliary power unit), which is the equipment that helped to start the engine, suddenly shut down,” Sadikin said.

The plane later landed safely at its destination in West Java after undergoing a check, Indonesia AirAsia chief executive Sunu Widyatmoko was quoted by local media as saying.

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