Boeing updates flight control software
Ethiopian Accident Investigation Bureau (AIB) has drafted the preliminary accident investigation report on the Ethiopian Airlines B737-8 MAX aircraft that crashed on March 10, 2019.
Sources told The Reporter that the AIB have analyzed the data retrieved from the Cockpit Voice Recorder (CVR) and Flight Data Recorder (FDR) from the doomed Flight ET302 that crashed few minutes after takeoff from the Addis Ababa Bole International Airport en route to Nairobi, Kenya. The preliminary report was expected to be released this week. However, this has been postponed. Sources said the AIB team has drafted the preliminary report adding that they are refining the report. “It could be released in the coming few days,” they said.
The AIB has five investigators and representatives of the US National Transport Safety Board (NTSB) and Boeing Co. are participating in the investigation process.
The Wall Street Journal yesterday reported that the Boeing 737 MAX Stall-Prevention feature was activated in Ethiopian plane crash. According to the newspaper, the emerging consensus is the strongest indication yet that the same Maneuvering Characteristics Augmentation System (MCAS) misfired in the fatal Ethiopian and Lion Air flights.
The newspaper stated that officials investigating the fatal crash of the Boeing 737 MAX have reached a preliminary conclusion that a suspect flight-control feature automatically activated before the plane nose-dived into the ground, the first findings based on data retrieved from the flight’s black boxes.
The MCAS flight control law was designed and certified for the 737 MAX to enhance the pitch stability of the airplane – so that it feels and flies like other 737s. Aviation experts assert that Boeing designed the MCAS to rectify the design flaw. The experts accuse Boeing for not properly communicating with customer airlines about the new flight control software.
In a related news the US aircraft manufacturer, Boeing, on Wednesday released a flight control software update which is attributed as the probable cause for the Ethiopian and Lion Air plane crashes.
In a statement Boeing said it has developed an MCAS software update to provide additional layers of protection if the Angle of Attack (AOA) sensors provide erroneous data. Angle of Attack is the difference between the pitch angle (nose direction) of the airplane and the angle of the oncoming wind.
Boeing said the software was put through hundreds of hours of analysis, laboratory testing, verification in a simulator and two test flights, including an in-flight certification test with Federal Aviation Administration (FAA) representatives on board as observers.
“Flight control system will now compare inputs from both AOA sensors. If the sensors disagree by 5.5 degrees or more with the flaps retracted, MCAS will not activate. An indicator on the flight deck display will alert the pilots. If MCAS is activated in non-normal conditions, it will only provide one input for each elevated AOA event. There are no known or envisioned failure conditions where MCAS will provide multiple inputs.”
Boeing said the pilots will continue to always have the ability to override MCAS and manually control the airplane. According to the company, these updates reduce the crew’s workload in non-normal flight situations and prevent erroneous data from causing MCAS activation.
“We continue to work with the FAA and other regulatory agencies on the certification of the software update,” Boeing said.
FAA has been criticized for delayed response in the grounding of the B737-8MAX fleet in the US. Responding to senators’ questions regarding the FAA’s timeline for grounding the Boeing 737 MAX, acting administrator Daniel Elwell, said he stood by the decision, which was based on a review of flight track data of the deadly Lion Air and Ethiopian Airlines crashes.
