The Boeing 737 MAX is Cleared for Takeoff: What Have we Learned?

Boeing 737 MAX Recertification Means it’s Ready to Fly

In the midst of the gloom that has settled over the airline industry in the wake of the COVID-19 pandemic, Boeing is experiencing perhaps its best news of 2020: the Boeing 737 MAX, which has been grounded worldwide for almost two years after two horrifying crashes in 2018 and 2019, has been cleared to fly worldwide. On the heels of this news, orders for the 737 MAX have begun coming in, with Irish budget airline Ryanair ordering 210 aircraft as part of its plan to expand its services across Europe.

What Caused the 737 MAX Air Disasters?

The story of the design flaws that led to the crashes is well known. When Boeing’s competitor Airbus announced an upgraded version of its A320 to compete with Boeing’s 737, Boeing decided to upgrade the 737. To get this done as quickly as possible, Boeing rushed through a series of redesigns, among them a larger and more fuel-efficient engine. However, the new engines needed to be placed further forward on the wing. The extra weight meant that during certain maneuvers, the nose of the plane would rise, which created the potential for a stall. Boeing therefore created a software application called the Maneuvering Characteristics Augmentation System (MCAS), which would use data from external sensors to determine the angle of attack and point the nose down when the weight of the engines pushed it up. However, the data from the sensors was not reliable, which meant that MCAS would push the nose down when it wasn’t necessary. From the perspective of the pilots, the plane was trying to crash itself into the ground. Even worse, the pilots had never been trained on MCAS or even informed that it existed. MCAS had also never been documented in any of the safety manuals the pilots used in emergencies. Boeing had done this intentionally so that they could avoid the expense and delay involved in training pilots on the new system. On October 29, 2018, Lion Air Flight 610 crashed into the Java Sea, killing all 189 people aboard. On March 10, 2019, Ethiopian Airlines Flight 302 crashed, killing 157 people. In both instances, the accident investigation revealed that the MCAS system had engaged and that the pilots were unaware of how to counter it before the planes plunged into the ground.

What’s Been Fixed on the 737 MAX?

For the last several months, Boeing has applied extensive corrective actions to the 737 MAX. First, MCAS will now use two external sensors instead of just one to ensure that MCAS gets the correct data regarding the angle of attack. If there is a discrepancy between the two data sources, MCAS will not engage. When MCAS does engage, it will only engage once to ensure that the pilots do not have an ongoing tug-of-war for control of the aircraft. Further, pilots will be able to override MCAS by pulling back on their control columns, after which MCAS will not automatically engage again, unlike the earlier version that re-engaged every five seconds. The FAA has also insisted that pilots be fully trained on MCAS and that all procedures relating to MCAS be fully documented. The estimated cost for re-engineering the 737 MAX is approximately $1 million per aircraft.

What Lessons Have Been Learned?

The improvements to the 737 MAX demonstrate that Boeing’s understanding of the importance of quality culture and systems thinking has improved and evolved. In particular, we should note the following:

Documented Processes

Systems that operate without proper documentation are essentially black boxes with no transparency. Proper documentation is crucial to ensure that all team members have a complete understanding of the design and optimal functioning of the system. Prior to the disasters, MCAS was not sufficiently documented in the cockpit manuals, which meant that the pilots were unaware of how to intervene when it began to point the plane towards the ground.

The Importance of Human Intervention

Automated systems that receive poor data can proceed towards goals that human operators would recognize as irrational. When MCAS received poor data suggesting the nose was too high, it pointed the nose down. In this sense, MCAS did exactly as it was designed to do. However, since the nose wasn’t too high, and MCAS was effectively putting the plane into a nosedive, the automated action was propelling the aircraft towards disaster. Humans would have understood this as an irrational goal and could have intervened, if they had known how to do so. The improvements to the MCAS will mean that the automated system can no longer operate unimpeded without opportunities for human intervention.

What Concerns Remain?

While the improvements to MCAS will go a long way towards winning back consumer confidence, concerns remain about the systemic problems that led to the disasters in the first place.

First, an investigation by the United States Congress revealed that Boeing operated within a “culture of concealment” that prioritized profit and speed of delivery over quality. During the production of the 737 MAX, employees and former employees asserted that Boeing engaged in practices like treating regulators with contempt, concealing information from pilots and key stakeholders, and failing to track parts defects along the supply chain. While Boeing has committed to improving in these areas, systemic and cultural issues like these will take time to uncover and resolve.

Second, and perhaps more importantly, it remains true that MCAS is a software workaround for a fundamental design flaw on the 737 MAX. MCAS was designed to make up for the fact that the larger engines have a negative impact on the stability of the plane. MCAS doesn’t fix that problem; it simply mitigates it. Quality should be designed into a product as a fundamental principle during the design stage, not added as an afterthought to accommodate a quality shortcoming.


By the time it’s flying again, the Boeing 737 MAX will be the most inspected aircraft in the skies. In all likelihood, this recertification will go a long way towards bringing an end to the purgatory in which the 737 MAX has existed for the last two years. For the families of the crash victims, that purgatory will never end. Boeing has done a great deal to win back consumer confidence with the 737 MAX. Hopefully, it will dedicate the same attention and resources to mending the systemic and cultural issues that gave rise to the disasters in the first place.


Aljazeera. (December 4, 2020). Budget line Ryanair orders 210 Boeing 737 Max jets for comeback. Accessed 2020.12.07.

BBC News. (December 2020). Boeing played Russian roulette with people’s lives. Accessed 2020.12.07.

CBC News. (December 2, 2020). Grounded 737 Max could take first step toward being cleared to fly this week, say crash victims’ families. Accessed 2020.12.07.

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