Boeing’s Role in Developing Flawed MCAS Software at Center of 737 MAX Crashes

Seattle, Washington – June 19, 2025 – The catastrophic crashes of Lion Air Flight 610 in 2018 and Ethiopian Airlines Flight 302 in 2019, which killed 346 people, have cast a harsh spotlight on the Maneuvering Characteristics Augmentation System (MCAS), a flight control software developed by Boeing for its 737 MAX aircraft. As investigations revealed critical flaws in MCAS, questions about its development process and Boeing’s engineering decisions have fueled debates over accountability and aviation safety.

Boeing’s In-House Software Development

Boeing, the Chicago-based aerospace giant, designed and developed MCAS as a proprietary software solution to address aerodynamic challenges in the 737 MAX, a modernized version of its bestselling 737 airliner. Introduced in 2017, the 737 MAX featured larger, more fuel-efficient engines mounted higher and farther forward, which altered the plane’s handling characteristics and increased the risk of stalls in certain flight conditions. To compensate without requiring extensive pilot retraining—a costly prospect for airlines—Boeing created MCAS to automatically adjust the plane’s horizontal stabilizer, pushing the nose down to prevent stalls and mimic the handling of older 737 models.

According to a 2019 report by The New York Times, MCAS was developed by Boeing’s internal engineering teams, primarily at its Seattle-area facilities. The software was integrated into the 737 MAX’s flight control computer, which relied on data from angle of attack (AOA) sensors to trigger adjustments. However, the design was flawed: MCAS depended on a single AOA sensor without redundancy, and Boeing increased its authority late in development, allowing it to make aggressive nose-down commands that pilots struggled to override.

Outsourcing and Cost Pressures

While Boeing’s core engineering team led MCAS development, reports from Bloomberg and The Seattle Times in 2019 revealed that the company outsourced portions of the 737 MAX’s software and systems work to lower-cost subcontractors to cut costs. One key subcontractor was HCL Technologies, an Indian IT firm, and Cyient, another India-based engineering company, which assisted with software coding, testing, and documentation for the 737 MAX’s flight control systems, including elements related to MCAS.

Engineers at HCL, some paid as little as $9 per hour compared to $45–50 for Boeing’s U.S. staff, worked on coding and verification tasks, according to Bloomberg. However, sources emphasized that Boeing retained oversight and final responsibility for MCAS’s design and integration. “The coding was done to Boeing’s specifications,” an HCL spokesperson told Bloomberg, clarifying that subcontractors followed Boeing’s directives.

Whistleblowers and former employees alleged that Boeing’s reliance on less-experienced, lower-paid contractors contributed to oversights. Mark Rabin, a former Boeing software engineer, told Bloomberg that “the process was rushed,” with insufficient scrutiny of critical systems like MCAS. A 2020 House Transportation Committee report criticized Boeing’s cost-cutting culture, noting that outsourcing and pressure to meet deadlines compromised safety.

Flawed Design and Lack of Transparency

The MCAS software’s flaws were catastrophic. Indonesia’s National Transportation Safety Committee (NTSC) and Ethiopia’s Aircraft Accident Investigation Bureau, in their 2019 and 2022 reports, respectively, found that MCAS’s reliance on a single AOA sensor led to erroneous activations, forcing the planes into unrecoverable dives. Boeing’s decision to omit MCAS from pilot manuals, fearing it would complicate training, left crews unprepared to handle malfunctions, as noted in the NTSC report.

Boeing’s internal reviews, later disclosed in a 2020 FAA audit, showed that engineers underestimated MCAS’s risks. The software was initially designed for limited stabilizer adjustments, but a late change—approved with minimal FAA oversight—increased its authority, amplifying its impact when triggered by faulty data.

Boeing’s Accountability and Reforms

Boeing has acknowledged responsibility for MCAS’s flaws, paying $2.5 billion in 2021 to settle a U.S. Justice Department charge of defrauding regulators by concealing MCAS’s risks. The company updated MCAS post-crash, adding dual-sensor redundancy and limiting its authority, as mandated by the FAA before the 737 MAX returned to service in December 2020.

Industry analyst Bjorn Fehrm told Business Insider in 2020 that Boeing’s management prioritized shareholder value over engineering rigor, a sentiment echoed on X in 2025, where users like @avgeek1

 wrote, “Boeing’s MCAS was a cheap fix to avoid retraining pilots, and they outsourced the code to cut corners. Lives were lost.”

Subcontractors’ Limited Role

HCL Technologies and Cyient have stated they were not directly responsible for MCAS’s design flaws. HCL told Reuters in 2019 that it “has a strong and long-standing relationship with Boeing” but did not develop the critical algorithms at fault. Cyient similarly clarified its role was limited to supporting tasks, not core design. The 2020 House report placed primary blame on Boeing for inadequate oversight of its subcontractors and flawed design choices.

Lessons Learned

The MCAS debacle has become a cautionary tale of software development gone awry under corporate pressure. As Gregory Travis wrote in IEEE Spectrum in 2019, “The MCAS software lacked basic fault tolerance… a failure of imagination by its developers.” The crashes have prompted calls for stricter oversight of software in aviation and greater transparency in development processes.

Boeing remains the primary developer of MCAS, with its engineering teams and leadership bearing responsibility for its failures. The tragedy underscores the risks of prioritizing cost over safety in critical systems, a lesson that continues to resonate in aviation today.

Sources:

• The New York Times, “Boeing 737 Max: What’s Happened After the 2 Deadly Crashes,” October 27, 2019

• Bloomberg, “Boeing’s 737 Max Software Outsourced to $9-an-Hour Engineers,” June 28, 2019

• The Seattle Times, “Boeing’s push to cut costs on 737 MAX included outsourcing,” March 17, 2019

• Indonesia National Transportation Safety Committee, Lion Air Flight 610 Report, 2019

• Ethiopia Aircraft Accident Investigation Bureau, Ethiopian Airlines Flight 302 Final Report, December 2022

• U.S. House Committee on Transportation and Infrastructure, “The Boeing 737 MAX: Examining the Design, Development, and Marketing,” September 2020

• IEEE Spectrum, “How the Boeing 737 Max Disaster Looks to a Software Developer,” April 18, 2019

• Business Insider, “Catastrophic software errors doomed Boeing’s airplanes,” February 29, 2020

• Reuters, “Boeing, Indian partner HCL clarify roles in 737 MAX software,” June 29, 2019

• Posts on X, June 12–13, 2025

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