One piece of debris from Malaysia Airlines Flight 370 has delivered the most significant picture so far of the last minutes of the flight, confirming that no human hand was in control of the Boeing 777 as it plunged into the Indian Ocean.

The Australian Transport Safety Bureau, ATSB, has spent many weeks analyzing a wing flap from the airplane, the largest piece of wreckage so far recovered. They have now ruled out that the flap was deployed by a command from the cockpit: It remained locked in place as it is during the cruise phase of a flight.

This was a decisive clue because the wing flaps can only be operated—for takeoff or landing—by direct pilot action. A flaperon, another piece of debris and the first to be discovered, in July 2015, on the island of Reunion in the western Indian Ocean, operates continually throughout a flight as part of the airplane’s automatic pilot system—and could not, therefore, indicate whether or not there was any involvement of pilots in its deployment.

The evidence provided by the wing flap—found on Pemba Island off the coast of Tanzania—is the only tangible indication so far that the Zombie Flight theory remains highly probable: that, for whatever reason, the 777 flew for its final hours at normal cruise height and speed on automatic pilot—until the engines ran out of fuel and it entered a death spiral, carrying 239 passengers and crew to their deaths.

New details given by the ATSB indicate that the jet hit the water at high speed, 284 mph, in a final descent of 25,000 feet a minute—that is more than twice the rate of the closest precursor of this scenario, the crash of Air France Flight 447 into the South Atlantic in 2009. The violence of the impact at this speed (calculated in revised computer simulations of the flight’s last seconds) means that the airplane shattered into many pieces.

As the ATSB delivered the latest update on their investigation, two search vessels have resumed working through the area where the remains of the airplane are believed to be, at great depths. Simultaneously, a three-day meeting is being held in Australia to consider whether the search area should be extended to the north of the present site.

Darren Chester, the Australian transport minister, said the experts would review “all the available data and analysis associated with the search to date… and develop guidance for any future search operations.”

However, The Daily Beast can reveal that the two ships now in the search area have a priority: to return to more than 30 previously searched sites. These are spread across the entire 120,000-square kilometer search area where sonar contacts were made but not at the time followed-up.

After these contacts were recently reviewed, they were classified as “having the potential to be manmade.” This does not mean the Australians believe they could be clues to where the airplane’s debris field may be, but that they have to be definitely ruled out before the search is complete.

Some experts have been critical of the performance of the Dong Hai Jui, the search vessel provided last year by the Chinese. The vessel had been operating for only a few days before it lost a towfish—a sonar scanning device towed by a long cable. By the time the towfish was recovered, the winter weather in the southern Indian Ocean was too severe for the vessel to continue searching.

The Dong Hai Jui is now back working at the northern end of the search area, together with the other search vessel, the Fugro Equator. The Equator is deploying an autonomous underwater vehicle, AUV, which is like a submarine and is the only equipment that can closely follow the contours of the most challenging underwater terrain, terrain that is fearsome in its aspect with hundreds of volcanoes spouting mud.

The Daily Beast can also reveal the Australians felt they needed more data to ensure that they could reliably recognize the characteristics of a crash debris field at great depth if the searchers came upon it. Over the last few months, they have requested and received data from two previously successful underwater searches, Air France Flight 447 in the Atlantic Ocean and the recent crash of EgyptAir Flight 804 in the Mediterranean Sea.

In both these cases, the debris fields consisted of one area where the heaviest parts of the airplane, the engines and landing gear, rested and a wider spread of smaller pieces scattered over the ocean floor. The best hope of locating the wreckage of Flight 370 would be to spot the sonar “signature” of the engines, each a large mass, and the landing gear.