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Boeing 737 Max Accidents

  1. Ethics Case Study: Boeing 737 Max (information current as of June 4, 2019)
  2. Boeing 737 Max Case Study October, 2018 and March, 2019 crashes Is it possible Boeing engineers violated professional ethics with regard to the MCAS anti-stall system that contributed to both of these plane crashes? This case study is based on information available as of June 4, 2019 and may change as further information becomes available Source: https://commons.wikimedia.org/wiki/File:Boeing_737-8_MAX_N8704Q_rotated.jpg
  3. Boeing 737 Max Case Study Applicable Codes of Ethics American Institute of Aeronautics and Astronautics • Hold paramount the safety, health, and welfare of the public in performance of their duties; • Avoid harming others, their property, their reputations or their employment through false or malicious statements or through unlawful or otherwise wrongful acts; • Issue statements or present information in an objective and truthful manner, based on available data; • Avoid real and perceived conflicts of interest, and act as honest and fair agents in all professional interactions; • Undertake only those tasks for which we are qualified by training or experience, or for which we can reasonably become qualified with proper preparation, education, and training; • Maintain and improve our technical and professional competencies throughout our careers and provide opportunities for the professional development of those engineers under our supervision; • Treat fairly and respectfully all colleagues and co-workers, recognizing their unique contributions and capabilities. • Promote the lawful and ethical interests of AIAA and the aerospace profession; • Reject bribery, fraud, and corruption in all their forms; • Properly credit the contributions of others, accept and offer honest and constructive criticism of technical work; and acknowledge and correct errors; https://www.aiaa.org/about/Governance/Code-of-Ethics
  4. Boeing 737 Max Case Study Applicable Codes of Ethics National Society of Professional Engineers Fundamental Canons Engineers, in the fulfillment of their professional duties, shall: 1. Hold paramount the safety, health, and welfare of the public. 2. Perform services only in areas of their competence. 3. Issue public statements only in an objective and truthful manner. 4. Act for each employer or client as faithful agents or trustees. 5. Avoid deceptive acts. 6. Conduct themselves honorably, responsibly, ethically, and lawfully so as to enhance the honor, reputation, and usefulness of the profession. These canons are general principles and require rules of practice for proper application https://www.nspe.org/sites/default/files/resources/pdfs/Ethics/CodeofEthics/NSPECodeofEthicsforEngineers.pdf
  5. Boeing 737 Max Case Study Applicable Codes of Ethics National Society of Professional Engineers Engineers, in the fulfillment of their professional duties, shall: 1. Hold paramount the safety, health, and welfare of the public. Rules of Practice for Canon #1 • If engineers’ judgment is overruled under circumstances that endanger life or property, they shall notify their employer or client and such other authority as may be appropriate. • Engineers shall approve only those engineering documents that are in conformity with applicable standards. • Engineers shall not reveal facts, data, or information without the prior consent of the client or employer except as authorized or required by law or this Code. • Engineers shall not permit the use of their name or associate in business ventures with any person or firm that they believe is engaged in fraudulent or dishonest enterprise. • Engineers shall not aid or abet the unlawful practice of engineering by a person or firm. • Engineers having knowledge of any alleged violation of this Code shall report thereon to appropriate professional bodies and, when relevant, also to public authorities, and cooperate with the proper authorities in furnishing such information or assistance as may be required. https://www.nspe.org/sites/default/files/resources/pdfs/Ethics/CodeofEthics/NSPECodeofEthicsforEngineers.pdf
  6. Boeing 737 Max Case Study October, 2018 and March, 2019 crashes What Happened? Source: https://commons.wikimedia.org/wiki/File:Boeing_737-8_MAX_N8704Q_rotated.jpg
  7. Boeing 737 Max What happened? Lion Air Flight 610 was a scheduled domestic flight operated by the Indonesian airline Lion Air from Jakarta (in Indonesia) to Pangkal Pinang (also in Indonesia). On October 29, 2018, Flight 610 (operated by the Boeing 737 MAX 8) crashed into the Java Sea 12 minutes after takeoff, killing all 189 passengers and crew. This was the first crash involving a Boeing 737 Max and the deadliest involving any 737 model.
  8. Boeing 737 Max What happened? On October 28, 2018, the same airplane experienced similar, repeated nose-down maneuvers as Flight 610. A third off-duty pilot who was also in the cockpit during that flight correctly identified the appropriate response from the quick action/quick reference guide in the cockpit. Unusual and repeated nose- down maneuvers which are intended to avoid stalling are called “runaway trim”
  9. Boeing 737 Max What happened? On October 28, 2018, the plane landed safely in Jakarta, having completed its flight as planned and on schedule. This same airplane reported problems with airspeed and altitude readings during four of the six flights that occurred in the three days prior to the crash. The sticker shaker activation (indicating an impending stall) that occurred on October 28 as a result of runaway trim is considered an “un-airworthy” condition. Was an “un-airworthy” airplane allowed to take off as Lion Air Flight 610 on October 29, 2018? https://commons.wikimedia.org/wiki/File:Lion_Air_Boeing_737-MAX8;_@CGK_2018_(31333957778).jpg https://www.popularmechanics.c om/flight/airlines/a25349919/lion- air-610-jet-not-airworthy/
  10. Boeing 737 Max What happened? On October 28, 2018, flight data indicated that the flight system carried out three maneuvers to adjust the nose downward, but the crew initiated steps to override it a little over eight minutes into the flight. The flight made it safely to its destination (Jakarta). The Boeing 737 Max has override switches that allow the pilot to take control over these repeated nose down maneuvers. The Quick Action/Reference guide advises such override during ”runaway trim” conditions.
  11. Boeing 737 Max What happened? On October 29, 2018, the pilots on Flight 610 were not able to identify the proper quick action and response procedure to stop the same airplane from similar runaway trim behaviors. Did these pilots have access to information regarding what had happened on the October 28, 2019 flight?
  12. Boeing 737 Max What happened? On March 10, 2019, Ethiopian Airlines Flight 302 was scheduled to fly internationally from Addis Ababa Bole International Airport in Ethiopia to Jomo Kenyatta International Airport in Nairobi, Kenya. The plane crashed in a field six minutes after takeoff, killing all 157 persons onboard.
  13. Boeing 737 Max What happened? Did the nose control (MCAS) system force Flight 302 into the ground? Was a sensor providing incorrect airspeed information? Did both occur? https://www.aviationcv.com/aviation-blog/2019/ethiopian-pilots-mcsas The jackscrew which controls the horizontal stability of the airplane involved in Ethiopian Air Flight 302 was found at the crash site in the full nose-down position.
  14. Boeing 737 Max What happened? After take-off, the Flight 302 airplane was going unusually fast (400 knots or 460 mph compared to a more typical 200-250 knots). The pilot requested permission to climb quickly – a request usually made and granted when the pilot needs extra space to maneuver an aircraft that is in trouble. Why was the airplane going too fast? Did a failed airspeed sensor contribute? Was human error involved? In travelling too fast, any attempts to override or correct nose-down movements are likely to have been ineffective. https://www.aviationcv.com/aviation-blog/2019/ethiopian-pilots-mcsas
  15. Boeing 737 Max What happened? After take-off, a sudden spike occurred in the black box data, indicating a potential anomaly in the angle of attack and airspeed sensors. Such a spike may have been created by an outside factor. https://www.reuters.com/article/us-ethiopia-airplane-reconstruction-insi/how-flawed-software-high-speed-other-factors- doomed-an-ethiopian-airlines-737-max-idUSKCN1RH0FJ Was sensor failure an issue in the Flight 302 crash? The sensor that would have caused such a spike in black box data has been implicated in multiple fatal accidents and other incidents in airplanes manufactured by both Boeing and others. https://commons.wikimedia.org/wiki/File:Angle_attack_sensor_hg.jpg
  16. Boeing 737 Max Case Study October, 2018 and March, 2019 crashes How does the Technology Work? Source: https://commons.wikimedia.org/wiki/File:Boeing_737-8_MAX_N8704Q_rotated.jpg
  17. Boeing 737 Max How does the Technology Work? The Boeing 737 Max is a modification of an old (and established) 737 design rather than a new (“clean sheet”) design. The original 737 (100 model) had its first flight in 1967. In strong competition with Airbus to reduce fuel consumption, Boeing chose to redesign the 737 rather than design an entirely new airplane. The first 737 Max was delivered to Southwest airlines in 2015 with 14% reduction in fuel consumption compared to the 737 NG (next generation) model.
  18. Boeing 737 Max How does the Technology Work? The FAA requires that a pilot operate only one type of aircraft. Thus, it is to any airline’s advantage to have as many of the same type of airplane as possible. This added to the incentive for Boeing to modify the 737 into the 737 Max rather than come up with an entirely new airplane design.
  19. Boeing 737 Max How does the Technology Work? The original 737 had folding metal stairs that attached to the fuselage of the aircraft in a design that was low to the ground to facilitate access to the airplane. The larger engines used in the 737 Max design had a larger fan diameter (69.4 inches) which facilitated better fuel performance. https://www.seattletimes.com/business/boeing-aerospace/u-s-pilots-flying-737-max- werent-told-about-new-automatic-systems-change-linked-to-lion-air-crash/ Maintaining a mandatory minimum ground clearance with the new and larger engines required larger landing gear and moving the engines up and forward
  20. Boeing 737 Max How does the Technology Work? The new geometry of the 737 Max caused by design changes required to facilitate larger, more fuel efficient engines, caused the airplane to pitch upward more frequently than previous 737 designs. The Maneuvering Characteristics Augmentation System (MCAS) was introduced to manage this tendency of the airplane to pitch up. https://en.wikipedia.org/wiki/Boeing_737_MAX#Structural_changes_and_other_improvements The MCAS system was not originally designed as a safety system but as an automatic control system intended to maintain the same handling as previous 737 designs.
  21. Boeing 737 Max How does the Technology Work? Angle of Attack is the angle between airflow and the position of the wing. Lift increases with Angle of Attack, but at a certain Angle of Attack, lift is lost, and the airplane stalls, unable to remain in the air. Speed decreases the Angle of Attack at which stall occurs. Angle of Attack can be computed from one of two types of sensors: wind vane types or pressure sensors. Most commercial jets use pressure sensors to calculate airspeed and the Angle of Attack. Angle of Attack sensors are placed in locations where measurement error is likely to be at a minimum.
  22. Boeing 737 Max How does the Technology Work? Angle of Attack using pressure sensors (pitot tubes) Air flows in to the tube at a certain flow velocity and is stopped, creating a stagnation pressure that can be used, along with static air pressure, to compute flow velocity, The flow velocity computed at an angle consistent with air flow across the wing can then be compared to the flow velocity at an angle consistent with the plane’s forward motion to determine the angle of attack In a pitot tube, the flow velocity (!) is related to the stagnation/total pressure ("#) and the static air pressure ("$) as follows: ! = 2("# − "$) * where * is the density of the air
  23. Boeing 737 Max How does the Technology Work? Pitot Tubes have caused a fatal aircraft accidents before.... • Air France Flight 447 (Airbus A330) on June 2009 crashed into the Atlantic ocean, killing 228 people. Icing of the pitot tube was partly to blame. Over 200 instances of angle of attack sensor (pitot tube) malfunction were reported since 2004, not just on Boeing planes.
  24. Boeing 737 Max What do we know? Pitot Tubes have caused more fatal accidents before ... • Birgenair (chartered) Flight 301 crashed on February 6, 1996, killing all 189 people on board. The cause of the crash was pilot error after getting wrong information from one of the airspeed pitot tubes – likely due to wasps creating a nest inside the tube. • Northwest Orient Flight 6231 crashed on December 1, 1974 and killed all three crew members on board. The cause of the crash was an iced over pitot tube. • Aeroperu Flight 603 (a Boeing 757) crashed en route from Miami to Santiago, Chile on October 2, 1996. Incorrect airspeed and altitude information on the cockpit displays were to blame (due in part to the cleaning crew leaving tape on the static inlet to a pitot tube). The pilots could not judge the airplane’s true altitude during night flight.
  25. Boeing 737 Max How does the Technology Work? The B737 Max MCAS (Maneuvering Characteristics Augmentation System) automatically trims the airplane’s nose down if a pre-determined angle of attack is sensed by the AOA (Angle of Attack) sensors in order to compensate for the altered geometry of the 737 Max, avoid an impending stall, and to create a handling experience similar to previous 737 models. This electronic trim control can be cut out by the pilot at any time in order to return manual control of the airplane’s angle of attack to the pilot. The switches that enable this return to manual control are located in the cockpit.
  26. Boeing 737 Max How does the Technology Work? Many airplanes use three angle of attack sensors that reduce the overall likelihood that an erroneous sensor reading will be taken seriously. The two of three sensors that provide the most consistent readings are assumed to be the fully operational and accurate sensors, while a third outlying reading is assumed to be erroneous and is ignored.
  27. Boeing 737 Max How does the Technology Work? The Boeing 737 Max uses only two angle of attack sensors and the MCAS system reads from only one angle of attack sensor at a time. The only indication of Angle of Attack is a disagree light in the cockpit that indicates when the angle of attack may be approaching a stall. An “optional” feature on the Boeing 737Max was a subsystem that would allow the pilot to see the readings of both angle of attack sensors and also see an indication of when the two sensors disagree.
  28. Boeing 737 Max Case Study October, 2018 and March, 2019 crashes What else do we know about these crashes? Is the 737 Max safe to fly? Source: https://commons.wikimedia.org/wiki/File:Boeing_737-8_MAX_N8704Q_rotated.jpg
  29. Boeing 737 Max What else do we know? The Boeing 737 Max uses only two angle of attack sensors and the MCAS system reads from only one angle of attack sensor at a time. Southwest Airlines will retrofit all of their 737 Max jets and require on any new 737 Max orders that an angle of attack indicator (rather than just a disagree or warning light) be present on the heads up displays that the pilot uses to be aware of the aircraft’s position and movement in the sky. Source: Wikimedia Commons In general, heads-up displays provide a less error-prone means to assess aircraft position and movement especially at night, during landing and takeoff, and during other low visibility or extreme events. These displays are often optional on commercial jets.
  30. Boeing 737 Max What do we know? And, MCAS takes 10 seconds to engage (automatically adjust angle of attack). In a crisis situation, this delay may be at odds with human ability to cognitively process and respond to the crisis. The MCAS system was originally certified to a maximum angle of attack adjustment of 0.6 degrees. Boeing later changed this to 2.5 degrees, while most of the rest of the world thought MCAS remained limited to 0.6 degrees. Further, the MCAS system was originally designed to offer take-off and landing handling similar to previous 737 models. A decision was made later on to keep MCAS on throughout flight.
  31. Boeing 737 Max What else do we know? It is not possible to include a simulated stall in flight simulators and too risky to create one in actual practice flights. Thus, pilots are trained to use angle of attack as well as air speed, altitude, and other indicators to diagnose impending stall. Most aircraft issue a warning when the airplane is at 1.3 times the stall speed.
  32. Boeing 737 Max Case Study October, 2018 and March, 2019 crashes What’s the bottom line? Source: https://commons.wikimedia.org/wiki/File:Boeing_737-8_MAX_N8704Q_rotated.jpg
  33. Boeing 737 Max the bottom line as we know it today At the engineering level: The MCAS system seems to be originally designed around enabling smooth take-off and landing and duplicating the handling of previous 737 models albeit with the bigger, more fuel-efficient engines of the 737 Max. After the initial MCAS design (and design intent), however, the system was expanded to operate during most of flight and allow up to 2.5 degree changes in the angle of attack. Combined with a 10 second delay in response, the system is confusing – which may explain why Boeing did not extensively train pilots in its use. Many changes appear to be made without considering the consequences on other parts of the system and other scenarios. Unanticipated consequences are a very common cause of failed technology and resulting human tragedy. This could be a failure by Boeing to keep track of the “big picture” – too many engineers focusing on only a small part of the system.
  34. Boeing 737 Max the bottom line as we know it today At the pilot level: The MCAS system is designed to be turned off (by pilots) if an angle of attack sensor goes bad. Heads-up displays seem to reduce the risk of a pilot misinterpreting the speed, position, altitude, or other parameters associated with the aircraft. There is a BIG difference between knowing how to fly a plane and knowing how and why a plane can fly. Knowing both is essential in a world where commercial jets are becoming more and more complicated. Whose fault were these fatal accidents? Likely the only thing we know for certain is that these 737 Max crashes were caused by more than one thing going wrong. A full understanding of the complex factors that contributed to the Lion Air and Ethiopian Air accidents is not yet available to the public.
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