Following the Indonesian Lion Air Flight 610 air crash in October 2018 that killed 189 people, the U.S. Transportation Department launched an inquiry into the Boeing 737 MAX.
According to a Wall Street Journal report, the U.S. Transportation Department which has been probing the Federal Aviation Administration’s (FAA) approval of the 737 MAX especially its new anti-stall control system known as MCAS (Manoeuvring Characteristics Augmentation System) has warned two FAA offices to safeguard computer files.
The Seattle Times also reported that Boeing’s original 737 MAX safety analysis of MCAS that was used by FAA to certify the aircraft had fundamental flaws. According to the report, the system had too much power and lacked redundancy. The situation may have been compounded by FAA rules that permit aircraft manufacturers to self-certify.
Seattle Times spoke to current and former engineers on condition of anonymity about the safety analysis of the 737 Max control system. Those engineers told the newspaper that the safety analysis allegedly
understated the power of the new flight control system, which was designed to swivel the horizontal tail to push the nose of the plane down to avert a stall."
The engineers said that the safety analysis report also claimed the system "failed to account for" the fact that it would reset when a pilot intervened. MCAS is designed to push the nose down if the 737 MAX's Angle of Attack (AOA) indicator detects an approaching stall or loss of aerodynamic lift.Angle of Attack
It is not easy defining what we mean by "angle of attack" without being too technical but I will try to explain it in the simplest way possible. In order for an airplane to fly, we must provide it with a lifting force at least equal to its weight. In that respect there is no difference between the airplane and the airship; it is in the method by which that lift is provided that the difference lies.
Take a piece of stiff cardboard, for instance, and push it through the air in such a way that it is inclined at a small angle to the direction in which you push it, the front or leading edge being directly above the rear or trailing edge. You will find that the result of pushing the cardboard through the air is to produce on it a force which tries to push it upwards and backwards. The upward part of this force we call lift and the backward part drag.
It is quite likely that the upward force will be sufficient to lift the cardboard which will be supported in the air. The cardboard is, in fact, acting like the wings or curved aerofoils of an airplane. So, if we push it through the air at a small angle - this angle is what is known as the angle of attack or the angle of incidence.
The angle of attack used in flight is a small one because although a larger angle would give more lift, it would also create disturbance and cause more drag. So far as the lift is concerned, it increases as we increase the angle of attack provided that the air speed remains constant but only to a certain limit; after this, it begins to fall off.
Although the actual amount of lift given by the wing when this maximum limit is reached varies tremendously according to the shape of the aerofoil or cambered wing section, it is rather curious that most wings, whatever their shape of section and whatever their air speed, reach their maximum lift at about the same angle, usually between 15º and 20º.
StallingIf, when flying in normal flight, the angle of attack is gradually increased, the speed will also decrease, there being a definite speed corresponding to each angle of attack. Therefore, when the stalling angle of the aerofoil or wing is reached, the airplane will be flying at a speed called the stalling speed of that airplane. If the angle of attack is further increased, the speed will continue to fall. Thus the lift fall will decrease rapidly, and for two reasons.
First, because the angle of attack is past the stalling angle, and secondly because the speed is decreasing. Since the lift only just equalled the weight of the stalling speed, it will obviously fall below it when the speed is less than the stalling speed, and therefore the airplane will start to fall, usually dropping its nose rapidly and going into a dive until it regains flying speed. It is in this dropping of the nose, and diving before speed and control are regained, that the danger lies. Considerable height may be lost, and if the original height was not sufficient, the airplane will strike the ground.
It is precisely because of this dangerous situation that most commercial aircraft use some form of "stick shaker" as a stall warning to pilots. Given the relative newness of the 737 MAX into the market, it may very well be possible that the MCAS system may have been triggered accidentally on both Ethiopian Airlines Flight 302 and Lion Air Flight 610 under normal flight conditions, possibly due to faulty Angle of Attack (AOA) indicators.Understanding the MCAS System
The Max 8 uses a system called MCAS which is designed to stabilize the aircraft in flight. Boeing added MCAS after redesigning its 737 platform for the Max. The redesign changed the size and placement of the aircraft’s engines, which altered how the jet handled in flight.
The Max tended to raise its nose in flight, a movement called pitch. If an aircraft pitches too high, it risks stalling and crashing.
MCAS is designed to automatically reduce the pitch in manual flight without pilot input. The system is constantly fed data from two synchronized wing-like devices called AOA sensors, located on the plane’s nose.
If the AOA sensors detect the plane is pitching too high, the MCAS automatically adjusts the tail’s stabilizer — the horizontal part of the aircraft’s tail — to level out the plane. However, if the AOA sensors feed faulty or contradictory data to the MCAS, the system can force the aircraft into a dive, according to a Boeing service bulletin issued on November 6.
In its original report, Boeing stated that:
The MCAS system could move the horizontal stabilizer to a maximum of 0.6º. Following the Lion Air crash, Boeing told airlines that MCAS could actually push controls 2.5º, or half the physical maximum. Boeing reportedly increased the limit because flight tests showed that a more powerful movement was needed to counteract an impending stall.
Because of that, MCAS could have pushed the nose down a lot more than the FAA thought possible. An engineer who spoke to Seattle Times on condition of anonymity said:
The FAA believed the airplane was designed to the limit of 0.6º limit, and that's what the foreign regulatory authorities thought too. It makes a difference in your assessment of the hazard involved."
Boeing reportedly failed to account for the fact that the MCAS system could reset itself after pilots intervened thus compounding the problem. What this means is that the system could continuously push the nose down causing a catastrophic loss in altitude. Boeing and the FAA allowed the MCAS system to be activated by a single Angle of Attack (AOA) sensor as opposed to two of them because failure of the system was designated "hazardous" rather than "catastrophic".
The fact that FAA rules allow manufacturers to do some certifications of aircraft by themselves adds to the problem. Boeing reportedly tried to speed up the process in order to catch up to their rival Airbus's A32Oneo and pushed the FAA to give it more responsibility. Development of the 737 MAX, which offers cost savings of about 15% on fuel, began in 2011 after the successful launch by its main rival of the Airbus A320neo. The 737 MAX entered service in 2017 after six years of preparation.
A former Boeing engineer had this to say:
There wasn't a complete and proper review of the documents. [the] review was rushed to reach certain certification dates."
The Federal Aviation Authority (FAA) said in a Monday statement,
We have no reports from whistleblowers [or] any other sources pertaining to FAA technical personnel being pressured to speed up certification of the Boeing 737 MAX."
Boeing, which is based in Seattle, echoed that statement with one of their own. Boeing said in their statement:
The 737 MAX was certified in accordance with the identical FAA requirements and processes that have governed certification of all previous new airplanes and derivatives. The FAA considered the final configuration and operating parameters of MCAS during MAX certification, and concluded that it met all certification and regulatory requirements."
Boeing sold the 737 MAX to airlines partly by pitching to airlines that pilots of older 737s would not need extensive retraining. The 737 MAX has larger more efficient engines that are mounted higher and further forward. Boeing developed the MCAS system to automatically correct for the altered aerodynamics and make the planes fly more like the earlier models.
Black box data obtained from the Lion Air Flight reportedly reveals that the system may have worked against the crew. After MCAS originally pushed the jet's nose down apparently due to a faulty AOA sensor, the pilots tried to regain control by hitting an override switch and pulling back on the controls. However, the system constantly fought back, and with the high 2.5º MCAS limit, could have pushed the nose all the way down after just two activation cycles. The aircraft eventually plunged into the sea at over 500 MPH.
Prior to the second crash, Reuters reported that the Lion Air Crash 737 MAX planes lacked a safety measure that might have helped the pilots to understand what was happening. Jets used by Southwest Airlines and other carriers had an "AOA DISAGREE" alert that can flag a faulty AOA sensor by comparing it to a second one. However, that backup system was reportedly optional and missing on both Ethiopian Airlines and Lion Air Jetliners.
This comes as Dagmawit Moges, Ethiopia's transport minister, said on Sunday that the latest crash showed "clear similarities" to a Lion Air crash with the same model of aircraft.
Dagmawit Moges told journalists that flight recorder data showed links between the crashes of Ethiopian Airlines Flight 302 on March 10 and Lion Air Flight 610 in October 2018. Moges didn't offer up specific details to support her claim, but she did say the government would release a detailed report within a month or so.
Boeing issued a statement shortly after the transportation minister's press conference on Sunday, but it did not address her claims directly. Boeing stated:
While investigators continue to work to establish definitive conclusions, Boeing is finalizing its development of a previously announced software update and pilot training revision that will address the MCAS flight control law's behavior in response to erroneous sensor inputs," the statement said. "We also continue to provide technical assistance at the request of and under the direction of the National Transportation Safety Board, the U.S. Accredited Representative working with Ethiopian investigators."
Boeing did not respond to the Seattle Times report due to the ongoing investigation, other than saying that "there are some significant mischaracterizations" Boeing has promised a software update, but the FAA has now grounded the entire 737 MAA fleet - well after other nations had already done so. In the meantime, however, both FAA and Boeing are facing heavy scrutiny over the 737 MAX certification process.
Argus Research cut Boeing stock to “hold” from “buy”, giving the aircraft manufacturer at least its fourth downgrade since the crash, Refinitiv data indicated. Shares of Boeing have been on the decline since the Ethiopian Airlines Flight 302 air crash on March 10, 2019. Boeing Company shares fell 3% on Monday, after the Wall Street Journal and Seattle Times Reports over the weekend raised more questions about the certification process for its 737 MAX jets before two recent deadly crashes. Boeing’s shares were down 2.8% at $369.20 in early trading, making them the biggest drag on the Dow Jones Industrial Average. Its shares, however, rose 0.3% on Tuesday, to close at $373.43. They are still down more than 11 percent since the crash in Ethiopia.
Richard Safran of Buckingham Research notes that:
The Inspector General of the U.S. Transportation Department is going to be looking for any issues with respect to how management handled the certification process. The FAA will be called on the carpet for its role in the certification process and any contribution to the MCAS issue."
The French aviation authority, BEA, which has been working with the Ethiopian investigators confirmed Monday that upon inspection, the plane's flight data recorder did show clear similarities to the recording from the Lion Air flight.
Officials with the National Transportation Safety Board (NTSB) said they are working with the full cooperation of Ethiopian authorities to transcribe and analyze information retrieved from the flight data recorder, but that data hadn't been verified as of Sunday afternoon, sources with knowledge of the investigation told the writer.
In a letter from Boeing CEO Dennis Muilenberg, the company acknowledged that
based on facts from the Lion Air Flight 610 accident and emerging data as it becomes available from the Ethiopian Airlines Flight 302 accident, we're taking actions to fully ensure the safety of the 737 MAX. Work is progressing thoroughly and rapidly to learn more about the Ethiopian Airlines accident and understand the information from the airplane's cockpit voice and flight data recorders.
The full letter follows below:
We know lives depend on the work we do, and our teams embrace that responsibility with a deep sense of commitment every day. Our purpose at Boeing is to bring family, friends and loved ones together with our commercial airplanes—safely. The tragic losses of Ethiopian Airlines Flight 302 and Lion Air Flight 610 affect us all, uniting people and nations in shared grief for all those in mourning. Our hearts are heavy, and we continue to extend our deepest sympathies to the loved ones of the passengers and crew on board.Safety is at the core of who we are at Boeing, and ensuring safe and reliable travel on our airplanes is an enduring value and our absolute commitment to everyone. This overarching focus on safety spans and binds together our entire global aerospace industry and communities. We’re united with our airline customers, international regulators and government authorities in our efforts to support the most recent investigation, understand the facts of what happened and help prevent future tragedies. Based on facts from the Lion Air Flight 610 accident and emerging data as it becomes available from the Ethiopian Airlines Flight 302 accident, we’re taking actions to fully ensure the safety of the 737 MAX. We also understand and regret the challenges for our customers and the flying public caused by the fleet’s grounding.Work is progressing thoroughly and rapidly to learn more about the Ethiopian Airlines accident and understand the information from the airplane’s cockpit voice and flight data recorders. Our team is on-site with investigators to support the investigation and provide technical expertise. The Ethiopia Accident Investigation Bureau will determine when and how it’s appropriate to release additional details.Boeing has been in the business of aviation safety for more than 100 years, and we’ll continue providing the best products, training and support to our global airline customers and pilots. This is an ongoing and relentless commitment to make safe airplanes even safer. Soon we’ll release a software update and related pilot training for the 737 MAX that will address concerns discovered in the aftermath of the Lion Air Flight 610 accident. We’ve been working in full cooperation with the U.S. Federal Aviation Administration, the Department of Transportation and the National Transportation Safety Board on all issues relating to both the Lion Air and the Ethiopian Airlines accidents since the Lion Air accident occurred in October last year.Our entire team is devoted to the quality and safety of the aircraft we design, produce and support. I’ve dedicated my entire career to Boeing, working shoulder to shoulder with our amazing people and customers for more than three decades, and I personally share their deep sense of commitment. Recently, I spent time with our team members at our 737 production facility in Renton, Wash., and once again saw firsthand the pride our people feel in their work and the pain we’re all experiencing in light of these tragedies. The importance of our work demands the utmost integrity and excellence—that’s what I see in our team, and we’ll never rest in pursuit of it. Our mission is to connect people and nations, protect freedom, explore our world and the vastness of space, and inspire the next generation of aerospace dreamers and doers—and we’ll fulfill that mission only by upholding and living our values. That’s what safety means to us. Together, we’ll keep working to earn and keep the trust people have placed in Boeing.Dennis MuilenburgChairman, President and CEOThe Boeing Company
Photo Credit: A Boeing 737 MAX 8 is pictured on the exterior of the Boeing Renton Factory in Renton, Washington. (Photo: Jason Redmond, AFP/Getty Images)