AirAsia is under investigation by the Indonesian Transport Ministry following a Friday news report that the airline wasn’t authorized to fly the Surabaya-to-Singapore route the day doomed Flight 8501 went down over the Java Sea.

The Dec. 28 crash occurred on a Sunday, but the Malaysian budget airline was only permitted to fly the route on Monday, Tuesday, Thursday and Saturday, according to a report from the Indonesian news organization BeritaSatu.

Search crews have now recovered 30 bodies from the AirAsia crash, five of whom were found still strapped in their seats, according to an Indonesian navy official. There were 162 people on board the flight when it fell.

Authorities are still trying to locate the plane’s black boxes as well as the remainder of the fuselage, but choppy water and bad weather continue to hamper recovery efforts. The black boxes could shed light on what caused the aircraft to end up in the sea.

Investigators believe the plane stalled as it climbed steeply to avoid a storm about 40 minutes into the two-hour flight.

Meanwhile, officials were hopeful Saturday they were honing in on the wreckage after sonar equipment detected two large objects on the ocean floor.

The objects were found early Friday by an Indonesian navy ship, and by midnight, searchers had zoomed in with a Geological Survey ship to take dimensions.

Investigators believe the plane stalled as it climbed steeply to avoid a storm about 40 minutes into the two-hour flight.