Pilots in doomed plane re-engaged suspect anti-stall system

Pilots of an airliner that crashed last month in Ethiopia initially followed Boeing's emergency steps by disconnecting a system that can force the nose of the plane down, but they could not regain control.

Data from the plane indicates that the pilots then broke from Boeing recommendations by reconnecting power to the system, according to an official familiar with the crash investigation.

The official spoke on condition of anonymity because a preliminary report on the March 10 crash has not yet been made public. Ethiopian investigators are expected to release the report on Thursday.

News that pilots of the Ethiopian Airlines Boeing 737 Max turned off a critical flight-control system suspected of playing a role in an earlier crash of the same model was first reported by the Wall Street Journal.

The newspaper said the pilots' actions are still being evaluated by investigators but could raise questions about assertions by Boeing and U.S. regulators last year that pilots could regain control in some emergencies by following steps that include turning off an anti-stall system designed specifically for the Max.

In a statement, Boeing urged against speculating before the preliminary report and flight data from the plane are released.

Investigators are examining the crashes that killed all 346 people aboard the two Max 8 jets, which were operated by Lion Air, an Indonesia carrier, and Ethiopian Airlines. They are looking into the role of a flight-control system known by its acronym, MCAS, which under some circumstances can automatically lower the plane's nose to prevent an aerodynamic stall.

The Max has been grounded worldwide pending a software fix that Boeing is rolling out, which must still receive approval from the Federal Aviation Administration and other regulators.

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Deadly Ethiopian Airlines crash kills all passengers thought to be onboard
People walk past a part of the wreckage at the scene of the Ethiopian Airlines Flight ET 302 plane crash, near the town of Bishoftu, southeast of Addis Ababa, Ethiopia March 10, 2019. REUTERS/Tiksa Negeri
Family members of the victims involved in a plane crash react at Addis Ababa international airport Sunday, March 10, 2019. An Ethiopian Airlines flight crashed shortly after takeoff from Ethiopia's capital on Sunday morning, killing all 157 people thought to be on board, the airline and state broadcaster said, as anxious families rushed to airports in Addis Ababa and the destination, Nairobi. (AP Photo/Mulugeta Ayene)
A family member of a victim involved in a plane crash talks on a mobile phone at Addis Ababa international airport Sunday, March 10, 2019. An Ethiopian Airlines flight crashed shortly after takeoff from Ethiopia's capital on Sunday morning, killing all 157 people thought to be on board, the airline and state broadcaster said, as anxious families rushed to airports in Addis Ababa and the destination, Nairobi. (AP Photo/Mulugeta Ayene)
Family members arrive at Bole International airport in Addis Ababa, Ethiopia, Sunday, March 10, 2019, to check on information on the Ethiopian flight that crashed. An Ethiopian Airlines flight crashed shortly after takeoff from Ethiopia’s capital on Sunday morning, killing all 157 people thought to be on board, the airline and state broadcaster said. (AP Photo/Elias Masseret)
Un avion des Ethiopian Airlines à destination de Nairobi s'est écrasé dimanche avec 149 passagers et huit membres d'équipage, a annoncé la compagnie. "Il n'y a pas de survivants à bord du vol, qui transportait des passagers de 33 pays", rapporte quant à elle la télévision publique, citant une source proche d'Ethiopian Airlines. /Photo d'archives/REUTERS/Amr Abdallah Dalsh
Family members arrive at Bole International airport in Addis Ababa, Ethiopia, Sunday, March 10, 2019, to check on information on the Ethiopian flight that crashed. An Ethiopian Airlines flight crashed shortly after takeoff from Ethiopia’s capital on Sunday morning, killing all 157 people thought to be on board, the airline and state broadcaster said. (AP Photo/Elias Masseret)
FILE - In this Jan. 25, 2010, file photo, Bole International airport in Addis Ababa, Ethiopia. An Ethiopian Airlines flight with 157 people thought to be on board crashed shortly after takeoff Sunday, March 10, 2019 from Ethiopia's capital headed to Nairobi, the airline said. (AP Photo/Samson Haileyesus-file)
Relatives of the victims involved in a plane crash wait for information Jomo Kenyatta International Airport, Nairobi, Kenya, Sunday, March 10, 2019. An Ethiopian Airlines flight crashed shortly after takeoff from Ethiopia's capital on Sunday morning, killing all 157 people thought to be on board, the airline and state broadcaster said, as anxious families rushed to airports in Addis Ababa and the destination, Nairobi. (AP Photo/Khalil Senosi)
Relatives of the victims involved in a plane crash wait for information at Jomo Kenyatta International Airport, Nairobi, Kenya, Sunday, March 10, 2019. An Ethiopian Airlines flight crashed shortly after takeoff from Ethiopia's capital on Sunday morning, killing all 157 people thought to be on board, the airline and state broadcaster said, as anxious families rushed to airports in Addis Ababa and the destination, Nairobi. (AP Photo/Khalil Senosi)
Kenya Airport Authority (KAA) Managing Director and CEO Jonny Andersen and Kenya's Transport Minister James Macharia (L) give a press conference on Ethiopia airline's crash in Ethiopia, at the Jomo Kenyatta International Airport in Nairobi, Kenya, on March 10, 2019. - An Ethiopian Airlines Boeing 737 crashed Sunday morning en route from Addis Ababa to Nairobi with 149 passengers and eight crew believed to be on board, Ethiopian Airlines said. (Photo by Yasuyoshi CHIBA / AFP) (Photo credit should read YASUYOSHI CHIBA/AFP/Getty Images)
Kenya Airport Authority (KAA) Managing Director and CEO Jonny Andersen speaks during a press conference on Ethiopia airline's crash in Ethiopia, at the Jomo Kenyatta International Airport in Nairobi, Kenya, on March 10, 2019. - An Ethiopian Airlines Boeing 737 crashed Sunday morning en route from Addis Ababa to Nairobi with 149 passengers and eight crew believed to be on board, Ethiopian Airlines said. (Photo by Yasuyoshi CHIBA / AFP) (Photo credit should read YASUYOSHI CHIBA/AFP/Getty Images)
A Chinese group send messages as informing about their colleagues who were allegedly onboard the plane that crashed in Ethiopia, at the Jomo Kenyatta International Airport in Nairobi, Kenya, on March 10, 2019. - An Ethiopian Airlines Boeing 737 crashed on March 10 morning en route from Addis Ababa to Nairobi with 149 passengers and eight crew believed to be on board, Ethiopian Airlines said. (Photo by Yasuyoshi CHIBA / AFP) (Photo credit should read YASUYOSHI CHIBA/AFP/Getty Images)
A Chinese group look at the arrival flight schedule as informing about their colleagues who were allegedly onboard the plane that crashed in Ethiopia, at the Jomo Kenyatta International Airport in Nairobi, Kenya, on March 10, 2019. - An Ethiopian Airlines Boeing 737 crashed on March 10 morning en route from Addis Ababa to Nairobi with 149 passengers and eight crew believed to be on board, Ethiopian Airlines said. (Photo by Yasuyoshi CHIBA / AFP) (Photo credit should read YASUYOSHI CHIBA/AFP/Getty Images)
A woman reacts as she waits for the updated flight information of Ethiopian Airlines Flight ET 302, where her fiance was onboard at the Jomo Kenyatta International Airport (JKIA) in Nairobi, Kenya March 10, 2019. REUTERS/Baz Ratner
People use their mobile phones near the flight information board displaying the details of Ethiopian Airlines Flight ET 302, at the Jomo Kenyatta International Airport (JKIA) in Nairobi, Kenya March 10, 2019. REUTERS/Baz Ratner
A flight information board displaying the details of Ethiopian Airlines Flight ET 302 is seen at the Jomo Kenyatta International Airport (JKIA) in Nairobi, Kenya March 10, 2019. REUTERS/Baz Ratner
A man looks at his phone outside the Ethiopian Airlines offices in downtown Nairobi, Kenya March 10, 2019. REUTERS/Thomas Mukoya
A woman walks with her child outside the Ethiopian Airlines offices in downtown Nairobi, Kenya March 10, 2019. REUTERS/Thomas Mukoya
BISHOFTU, ETHIOPIA - MARCH 12: Investigators with the U.S. National Transportation and Safety Board (NTSB) look over debris at the crash site of Ethiopian Airlines Flight ET 302 on March 12, 2019 in Bishoftu, Ethiopia.. All 157 passengers and crew perished after the Ethiopian Airlines Boeing 737 Max 8 Flight came down six minutes after taking off from Bole Airport. (Photo by Jemal Countess/Getty Images)
People work to search for belongings and debris for forensic analysis at the crash site of the Ethiopian Airlines operated Boeing 737 MAX aircraft in which their relatives perished among the 157 passengers and crew onboard, at Hama Quntushele village, near Bishoftu, in Oromia region, on March 15, 2019. - A French investigation into the March 10 Nairobi-bound Ethiopian Airlines Boeing 737 MAX crash that killed 157 passengers and crew opened on March 15 as US aerospace giant Boeing stopped delivering the top-selling aircraft. (Photo by TONY KARUMBA / AFP) (Photo credit should read TONY KARUMBA/AFP/Getty Images)
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The official who discussed the matter with The Associated Press said that data downloaded from the plane's so-called black boxes indicates that the pilots of Ethiopian Airlines Flight 302 followed recommendations by flipping two switches that disconnected power to the system. Sources told the Journal that despite that step, the pilots could not make the plane climb.

The pilots then reversed the power switches that they had turned off — a step not included in Boeing-approved recovery procedures — which reactivated MCAS and pushed the plane's nose down, the official told the AP. Boeing's procedures instruct pilots to leave the MCAS system disconnected and continue flying manually for the rest of the flight.

Boeing developed MCAS for the Max because the plane has larger engines that sit higher and more forward under the wings than the engines on previous 737s, which gives the new model a greater tendency for the nose to tip upward in some situations.

John Goglia, a former member of the National Transportation Safety Board, said MCAS was designed largely to reduce the nose-up effect during takeoff and avoid a dangerous aerodynamic stall, or loss of lift from air flowing over the wings.

Pilots can turn off MCAS by pressing a button on their control column, although the system can resume if pressure is released. If pilots opt instead to disable the system by flipping a pair of toggle switches, it cuts power to part of the tail called a horizontal stabilizer used to point the plane up or down. Flipping the switches requires pilots to manually turn a wheel to operate the stabilizer.

"The pilot not flying should be cranking that wheel," Goglia said.

If the Ethiopian pilots followed all of Boeing's procedures and disengaged the MCAS but the plane still crashed, the company has some explaining to do, he said. But, he added, restoring power to the system "is not in the procedure."

Boeing is the focus of investigations by the Justice Department, the Transportation Department's inspector general, and congressional committees. Investigations are also looking at the role of the Federal Aviation Administration, which certified the Max in 2017 and declined to ground it after the first deadly crash in October.

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