The latest word from the investigation of last week’s crash of an Ethiopian Airlines Boeing 737 MAX 8 jet is that readings retrieved from the flight data recorder reportedly point to circumstances similar to those that surrounded a 737 MAX crash less than five months earlier in Indonesia.
Regulators around the world suspected as much, based on data received via satellite from the plane during its minutes-long flight from Addis Ababa heading for Kenya on March 10. That’s what led them to ground hundreds of 737 MAX 8 and MAX 9 planes last week.
The March 10 crash killed all 157 people aboard Ethiopian Airlines Flight 302, while the October crash killed all 189 people aboard Lion Air Flight 610.
In the Lion Air investigation, safety experts focused on an automatic flight control system known as the Maneuvering Characteristics Augmentation System, or MCAS. Boeing added the MCAS system to the 737 MAX to guard against having the airplane stall under extreme conditions. The measure was taken because the MAX’s engines are bigger than the engines on the previous line of 737s, changing the aerodynamics.
Preliminary findings from the Indonesia probe suggested that the MCAS system was receiving spurious data about the plane’s aerodynamic “angle of attack” just after takeoff. That would lead the automatic system to force the plane’s nose downward into an uncalled-for dive.
In the Lion Air case, the pilots repeatedly fought against the MCAS commands — and ultimately lost. Afterward, Boeing said pilots can use a procedure to disengage the MCAS system, but that procedure wasn’t followed by the Lion Air pilots.
Today, Reuters quoted an unnamed source as saying the angle-of-attack readings from the Ethiopian Airlines jet’s flight data recorder were “very, very similar” to the Lion Air readings. The similarities will be the focus of further investigation, Reuters quoted its source as saying.
The double disaster has raised deeper questions about the Federal Aviation Administration’s oversight of Boeing during the certification of the 737 MAX. Over the weekend, The Seattle Times quoted sources as saying that Boeing pressed the FAA to accept analyses that company engineers had done assessing the MCAS system’s safety.
The Times said those analyses understated how much leeway the automatic system was given to move the horizontal tail in order to avoid a stall — or force a dive if the system malfunctioned. Another potential flaw with the system was that it depended on readings from a single angle-of-attack sensor, rather than multiple sensors.
Much of The Seattle Times’ report was based on research conducted before the Ethiopian Airlines jet crashed. Aerospace reporter Dominic Gates wrote that “both Boeing and the FAA were informed of the specifics of this story and were asked for responses” a few days before the crash.
People shouldn’t misread this point.
I was not telling Boeing or the FAA anything they didn’t know.
As noted, Boeing has been working since the first crash on a fix for the flaws my story listed https://t.co/zHtpVDNdxy
— Dominic Gates (@dominicgates) March 18, 2019
In a video statement released today, Boeing CEO Dennis Muilenburg said that “safety is at the core of who we are at Boeing” and that the company is working with authorities and airlines to support the investigation and “help prevent future tragedies.”
“Soon we’ll release a software update for the 737 MAX that will address concerns discovered in the aftermath of the Lion Air Flight 610 accident,” Muilenburg said. That update, and revisions in pilot training procedures, should address the MCAS’ behavior in response to erroneous sensor inputs, Boeing says.
The Wall Street Journal reported today that Justice Department and Transportation Department officials are reviewing how the 737 MAX was developed, and how the plane won its regulatory approvals. Transport Canada is also reviewing the validation it gave to 737 MAX jets.
U.S. Sen. Roger Wicker, R-Miss., has said he intends to hold a hearing into the issues raised by the crashes, in his capacity as the chairman of the Senate Commerce, Science and Transportation Committee.
The committee’s ranking Democratic member is Sen. Maria Cantwell, D-Wash. She touched on the matter briefly in response to a question today at the Northwest Quantum Nexus Summit in Seattle.
“Paramount in all of this is safety,” Cantwell told GeekWire. “So we’re going to keep looking at all the data and information until we are sure that we understand every aspect of this.”