El Software Que Mató A 346 Personas

The Tragic Consequences of Software Design Failures

Introduction to Software's Role in Aviation

• The discussion begins with the omnipresence of software in modern life, highlighting its dual role as a facilitator and a potential source of disaster.

• A specific incident is introduced: the crash of two commercial airplanes due to software and engineering design flaws, resulting in 346 fatalities.

The Boeing 737 Max Incident

• On October 29, 2018, Lion Air Flight 610 crashed shortly after takeoff from Jakarta, Indonesia. The aircraft was a Boeing 737 Max with serious undisclosed design issues.

• Prior flights experienced alarming altitude drops and control issues; however, the crew managed to land safely. Unfortunately, the next flight faced catastrophic failure.

Boeing's Competitive Challenges

• To understand the crisis, it's essential to explore why Boeing implemented controversial design changes for the 737 Max amidst increasing competition from Airbus.

• The Boeing 737 has evolved since its inception in 1967 but faced stiff competition from Airbus’s A320 Neo family launched in 2010, which offered superior fuel efficiency.

Design Decisions Leading to Disaster

• Faced with declining market share and pressure to compete quickly, Boeing opted for an upgrade rather than developing a new model from scratch.

• Engineers were reluctant about modifying an aging design that had undergone numerous changes over decades. New engines required different placements on the aircraft.

Aerodynamic Challenges and MCAS Introduction

• The repositioning of larger engines altered the plane's aerodynamics significantly; this necessitated pilot retraining which Boeing aimed to avoid.

• As a solution, they introduced MCAS (Maneuvering Characteristics Augmentation System), designed to automatically adjust stabilizers based on angle-of-attack readings.

Functionality and Risks of MCAS

• MCAS was intended to make handling similar to previous models while preventing stalls by lowering the nose if necessary.

Boeing's MCAS System: A Critical Overview

Activation and Limitations of MCAS

• The MCAS (Maneuvering Characteristics Augmentation System) is only activated at high speeds, with a maximum stabilizer movement of 0.6 degrees. Boeing documented these limitations for FAA certification.

• Boeing made significant changes by removing the high-speed condition for activating MCAS, allowing it to engage at low speeds and increasing its power from 0.6 to 2.5 degrees.

• Instead of using both angle-of-attack sensors, Boeing opted for a single sensor, introducing a single point of failure without notifying the FAA about these critical changes.

Engineering Challenges and Pressures

• Engineers faced immense pressure in a challenging work environment where expressing concerns was difficult; they were compelled to prioritize stock values over safety.

• The new aircraft model became successful quickly due to its efficiency, requiring minimal pilot retraining—only two hours on an iPad that did not mention MCAS.

Incident Preceding Lion Air Flight 610

• On October 28th, one angle-of-attack sensor was replaced but miscalibrated by 21 degrees, leading to incorrect readings that went undetected.

• Prior flight experienced multiple issues due to the faulty sensor; alarms were triggered as discrepancies between the two sensors caused confusion among pilots.

Flight Lion Air 610: Sequence of Events

• During Lion Air Flight 610 shortly after takeoff, erroneous angle-of-attack readings led to vibrations in the control column as the plane seemed to be entering a stall.

• Pilots believed there was an issue with the stabilizer and attempted emergency procedures but continued facing alerts indicating potential loss of control.

Final Moments and Aftermath

• An alert called "AOA Disagree" should have indicated discrepancies between sensors but was optional equipment that few airlines purchased; thus it wasn't included in reports.

• Shortly after takeoff, incorrect angle-of-attack readings led to continuous activation of MCAS despite pilots' attempts to regain control through various maneuvers.

Boeing 737 Max: A Tragic Series of Events

The Role of MCAS and Pilot Procedures

• Boeing's communication indicated that airlines had manuals detailing procedures for handling issues related to the MCAS system, including shutting off stabilizer switches.

• Despite acknowledging that MCAS played a role in the accidents, Boeing continued to blame pilots for not following documented procedures.

• The Ethiopian Airlines Flight 302 crash occurred on March 10, 2019, with no survivors; data from black boxes revealed that MCAS was again responsible despite pilots following procedures.

Sensor Malfunctions and Emergency Responses

• Shortly after takeoff, one angle-of-attack sensor began providing erroneous readings, leading to a significant discrepancy between sensors.

• Pilots attempted to disable MCAS by cutting power but lost control over stabilizer switches needed to regain stability.

• In a desperate move, they reactivated the stabilizer switches but were unable to recover control before crashing at high speed.

Internal Documents and Regulatory Oversight

• Internal documents revealed that if MCAS activated incorrectly, pilots had less than ten seconds to respond or face catastrophic outcomes.

• An FAA audit estimated that without corrections, the 737 Max could experience an accident every two years, marking it as potentially the most dangerous aircraft in modern aviation.

Global Reactions and Consequences

• Following the second crash, countries worldwide grounded all 737 Max flights; the U.S. delayed action until confirming findings from black box data.

• It was discovered that MCAS had a single point of failure risk; this oversight led to serious safety concerns regarding its operational protocols.

Training Issues and Legal Ramifications

• Lion Air requested additional training from Boeing prior to their accident but was dismissed internally by Boeing staff.

• All 737 Max planes were grounded for 20 months while software updates were developed; Boeing faced criminal conspiracy charges resulting in a $2.5 billion settlement.

Return to Service and Ongoing Concerns

• After extensive revisions and testing due to COVID-related delays, the 737 Max was cleared for flight again in November 2020.