The chairman of Boeing acknowledged Thursday for the first time that a new maneuvering system was responsible for two plane crashes that killed almost 350 people, and he apologized to the families and friends of the victims.

"We at Boeing are sorry for the lives lost in the recent 737 accidents and are relentlessly focused on safety to ensure tragedies like this never happen again," CEO Dennis Muilenburg said in a videotaped statement posted on Twitter.

Muilenburg said the details of airline accidents normally await a final report from governments, "but with the release of the preliminary report of the Ethiopian Flight 302 accident investigation, it is apparent that in both flights, the Maneuvering Characteristics Augmentation System, known as MCAS, activated in response to erroneous angle of attack information."

That preliminary report, issued Thursday, indicated the crew of the Ethiopian Airlines jet that crashed last month, killing all 157 people aboard, performed all procedures recommended by the aerospace giant but failed to gain control of the doomed aircraft.

The report reveals details of the crew's intense but ill-fated efforts to save the Boeing 737 Max from catastrophe.

Muilenburg, who spoke from the floor of a Boeing hangar, said the history of the aviation industry shows that most accidents are caused by a "chain of events," and the latest tragedies are no exception.

"We know we can break one of those chain links in these two accidents," he said. "As pilots have told us, erroneous activation of the MCAS function can add to what is already a high workload environment. It's our responsibility to eliminate this risk. We own it, and we know how to do it."

The jet experienced “nose dive conditions” almost immediately after takeoff, Ethiopian Minister of Transport Dagmawit Moges said.

"The crew performed all the procedures repeatedly provided by the manufacturer but were not able to control the aircraft," Moges said at the news conference in the capital, Addis Ababa.

Peter Goelz, former managing director of the National Transportation Safety Board, said the report thickens the cloud hanging over Boeing and the FAA since the tragedy, the second crash of a Boeing 737 Max in five months.

Boeing updated its instructions on handling such an emergency after a Lion Air crash in Indonesia in October that killed all 189 people aboard.

"The news is that the pilots followed the instructions from Boeing that were endorsed by the FAA, and it didn't save the plane," Goelz told USA TODAY. "I don't see these planes getting back in the air anytime soon."

The report recommends that the flight control system should be reviewed by Boeing and that aviation authorities should verify the system before the aircraft is released to operation, Moges said.

The report describes how the plane was less than two minutes into its flight from Addis Ababa on March 10 when one of the angles of attack sensors began providing faulty information, indicating an imminent stall. The pilots repeatedly tried without success to pull the jet's nose up, the report revealed.

"The captain called out three times 'pull up' and the first officer acknowledged," according to the report.

The aircraft's automated anti-stalling system, the MCAS, tried to force the nose down multiple times, the report says.

The pilots followed emergency procedures and turned off the system, the report says. The pilots tried to use the backup manual wheel, but the airplane was traveling too fast, according to the report. The jet crashed six minutes into takeoff.

The crash site was consistent with "high energy impact."

"The aircraft impacted in a farm field and created a crater approximately 10 meters deep, with a hole of about 28 meters width and 40 meters length," the report says. "Most of the wreckage was found buried in the ground."

A final report on the crash could be a year away, Moges said.

Also Thursday, the Washington Post reported that federal aviation regulators have ordered Boeing to fix a second problem with the flight-control system. Citing unnamed sources, the Post said the software problem pertains to software affecting flaps and other flight stabilization hardware.

Boeing said it is working on a software update for the MCAS. The FAA stressed in a statement that the report was preliminary and based on information "obtained during the early stages" of the investigation.

The FAA and NTSB remain involved in the investigation, the statement said.

"We continue to work toward a full understanding of all aspects of this accident," the FAA said. "As we learn more about the accident and findings become available, we will take appropriate action."

Moges has said preliminary data, obtained mostly from the plane's voice and data recorders, indicated "clear similarities" between the Indonesian and Ethiopian crashes. At issue is the MCAS installed on 737 Max aircraft to help compensate for heavy engines placed more forward on the wings.

Ethiopian officials rejected media reports that a bird strike may have damaged an angle of attack sensor that apparently fed incorrect information to the plane's MCAS.

In such an emergency, Boeing’s procedures instruct pilots to disconnect the MCAS and fly manually for the rest of the flight.

In a statement Thursday, Ethiopian Airlines said the preliminary report "clearly showed" that the pilots of the flight "followed the Boeing recommended and FAA approved emergency procedures to handle the most difficult emergency situation created on the airplane."

"Despite their hard work and full compliance with the emergency procedures, it was very unfortunate that they could not recover the airplane from the persistence of nose diving. As the investigation continues with more detailed analysis, as usual we will continue with our full cooperation with the investigation team," the airline's statement said.

After the Ethiopian disaster, 737 Max jets were grounded worldwide, pending a software fix Boeing is rolling out. The FAA said it expects to receive Boeing's software improvement plan for the 737 Max aircraft within weeks. The agency promised rigorous review before approving installation of any fixes.

Also at issue are thousands of the planes on order worldwide.

University of Richmond law professor Carl Tobias, an expert in product liability, said the report does not bode well for Boeing – at least in the short term.

"All of the planes could be grounded for a while, and it raises questions about the planes now on order and being built," Tobias said. "These are mostly about economics, but the report may also implicate Boeing’s decisions in designing and certifying the plane and the FAA’s regulatory oversight."

Contributing: The Associated Press

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