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The Rise and Fall and Return of the Boeing 737 MAX

Sep 2, 2021 12:00 PM 7 min read

The Federal Aviation Administration (FAA), America’s and by extension the world’s foremost civil aviation regulator, cleared Boeing's 737 MAX planes to fly after a hiatus of 20 months back in November 2020. And now they are set to return to the Indian skies.

Last Thursday, the Directorate General of Civil Aviation (DGCA), India’s FAA counterpart, lifted its ban as well, in place since March 13th 2019. This leaves China as the only other leading aviation market yet to allow the aircraft to resume service.

But why were the 737 MAX planes grounded in the first place?

A Series of Unfortunate Events

Back in October 2018, a Lion Air flight travelling from Jakarta crashed into the Java Sea 13 minutes after takeoff, killing all 189 passengers and crew onboard. Only five months later, an Ethiopian Airlines flight travelling from Addis Ababa crashed six minutes after takeoff, killing all 157 people onboard.

These two fatal accidents prompted numerous countries to ground all 737 MAX operations and demand an investigation into its perceived safety risks and how it was approved by the FAA for service in the first place.

FYI: Don’t confuse the above crashes with the MH370 jet, which disappeared over the South China Sea in March 2014, and whose debris still remains missing. That was a Boeing 777-200ER aircraft.

How did the two back-to-back calamities happen? To answer this question, we need to travel back a decade...


“You’re Gonna Need a Bigger Engine”

Boeing and Airbus command a duopoly in the global aircraft manufacturing market. Their rivalry (which we’ll discuss in a bit) is heated, and both race against time to develop new features and innovations that can make their aircraft models more attractive to buyers.

By 2010, Boeing was eager to update its flagship 737 line of jetliners. The 737 family was widely popular and lucrative - but also severely outdated (it entered service in 1968). So a new line of single-aisle Boeing airliners was on the cards.

Out of the blue, Airbus made an announcement. Its popular line of narrow-body jets - the A320 - would receive an important update. The A320neo would have new geared turbo-charged engines that would be larger than earlier models but, significantly, would be about 15% more fuel efficient. Crucially, Airbus said this update wouldn’t require pilots to get additional training - they could just hop on to the advanced planes and fly them just like the earlier iterations.

Naturally, Boeing was alarmed at this development. It rushed to abandon its plans to design a new line of aircraft, which would have taken more time and effort. Instead, it sought to update the existing 737 line akin to the A320neo - i.e. Equip it with larger and better engines.

That’s where the problem began. 


Engineering a Catastrophe

During takeoff, a plane needs increased lift (upward force on the aerofoil caused by downward deflection of the air below the wing) to carry it forward. This is done by increasing the Angle of Attack (AoA), which is the angle between the nose of the plane and the direction of the flight.

Since “flight speed” is relatively low during takeoff, a steep AoA is needed to generate sufficient lift. If the AoA however becomes too steep relative to the slow speed (i.e. Hit the “critical” AoA = ~15 degrees), the aircraft starts stalling nose-up. Translation: it loses lift. In that scenario, the airplane’s nose needs to be brought down to secure the lift.

It is a fine balance (or dance if one comes to think of it) which needs to be maintained especially during takeoff and landing.

737 jets have much lower ground clearance than the A320. The latter could afford a larger engine without altering the aerodynamics of the aircraft. The 737, however, was too close to the ground to afford a bigger engine without creating the possibility of a nose-up stall.

Boeing’s workaround? Move the engine higher up. Above the wings. Enter, increased fuel efficiency. Enter, the 737 MAX.

Now, to compensate for the changes in placement and size of the engines, a software called Maneuvering Characteristics Augmentation System (MCAS) was installed. This was an automatic mechanism that used an AoA sensor to identify if the aircraft was flying at too steep an angle and to readjust it (by bringing its nose down) in such a scenario.


A Tale of Two Tragedies

The Lion Air and Ethiopian Airlines crashes were a result of a failure in the AoA sensor and misreading by the MCAS. Crucially, it was also due to lack of requisite training. Boeing claimed that, just like the A320neo, pilots needed minimal additional training to fly its updated jets. In many cases, only a two-hour iPad training course was provided. Moreover, the existence of MCAS was not disclosed to the pilots until after the Lion Air accident. Even following this, simulation training was not mandated until after the Addis Ababa crash.

The Rise and Fall and Return of the Boeing 737 MAXLet’s dive a little deeper. In October 2018, the MCAS on the Lion Air 737 MAX forced the nose of the aircraft down 26 times in 10 minutes. The pilots on board didn’t know what was happening, and tried to fight the software. But the sensor was relaying incorrect data (i.e. The sensor was “thinking” the AoA was too steep, while it wasn’t in reality), forcing the plane down. Minutes later, the flight crashed.

Boeing, which now finally revealed the existence and working of the MCAS, tried to deflect the blame on pilot inexperience and other factors. However, the Final Report of Indonesia’s Lion Air Accident Investigation, which placed some of the blame on the pilots and maintenance crews, concluded that Boeing and the FAA were primarily responsible for the crash.

Despite continuing to hold that the MCAS was not responsible, Boeing proceeded to update the system by adding more sensors, placing a cockpit indicator light to indicate if the sensors disagreed, and limiting the number of times and the extent to which the MCAS could be activated. But the company continued to hold that pilot simulator training was not required for even the redesigned MCAS system (it finally relented on this only in January 2020).

In March 2019, the Ethiopian Airlines tragedy occurred. Boeing followed by acknowledging for the first time that the MCAS played a primary role in the crashes, but also highlighted other factors, like pilot error. But this stance remained tenuous: a month after the second crash, then-CEO Dennis Muilenburg said the MCAS system:

...was designed per our standards, certified per our standards, and we're confident in that process. So, it operated according to those design and certification standards. So, we haven't seen a technical slip or gap in terms of the fundamental design and certification of the approach.”

However, a report on the crash by the Ethiopian government exonerated the pilots and the airline, instead placing the blame on design flaws in the 737 MAX. Meanwhile, a soaring number of countries had grounded the jet, escalating a PR nightmare for Boeing.

FYI: Even before the Jakarta crash, pilots were complaining that the MAX struggled to stay up during takeoff. But these warnings probably fell on deaf ears at Boeing HQ. Because the 737 MAX, which entered service in 2017, was an instant bestseller. It immediately became the most popular model in the 737 family, and helped the company get a leg up over Airbus.


Boeing vs Airbus: The Fight for Aerial Supremacy

Boeing is the world’s oldest aircraft manufacturer. It introduced the first commercial jetliner (the 707) in 1958. The 737 line was nothing short of an engineering revolution. These long-range airliners came with larger seating capacity, were more efficient than other models of the time, and solidified Boeing’s position in commercial aviation. In effect, the company enjoyed a practical monopoly in the industry for decades - until Airbus emerged in 1970.

By the 1990s, Airbus became a significant competitor to Boeing, with its novel offerings such as the A330 and the A340. It was boosted by a rapidly growing airline market and by its timely bets in the Asia Pacific region. It also received a fillip from generous European state subsidies.

The latter point has been a lightning rod for trans-Atlantic tensions. The Boeing vs Airbus clash has evolved into a US vs EU one, with each side accusing the other of anticompetitive practices. This conflict, which was the longest-running trade dispute at the WTO, deserves an EOD deep-dive of its own. But suffice it to say that it was seemingly resolved in June this year when US President Joe Biden signed a temporary détente with European Commission President Ursula von der Leyen.


The 737 MAX Comeback

The investigation into the aircraft’s design flaws led to Boeing further amending the MCAS and setting up simulators and training centres for pilots. In November 2020, the FAA lifted its restrictions on the jet. Other countries, including Japan, Europe, UK, Canada, Brazil, UAE, Australia etc followed suit. With India doing the same, China is the only major country yet to approve the MAX.

Explaining its decision, the DGCA said that 17 regulators worldwide have permitted operation of these planes, and 34 airlines with 345 planes had operated over 2.89 lakh cumulative hours since December 2020 “with no untoward reporting”.

FYI: In India, SpiceJet is the only operational carrier with 737 MAX aircraft in its fleet. Presently-grounded Jet Airways also has these jets. And the upcoming domestic airline Akasa (backed by Rakesh Jhunjhunwala) is expected to launch with a fleet of MAX.


The Bottom Line

The uniqueness of the 737 MAX saga is the difficulty in pinning the blame on one person.

The entire designing process was flawed. The haste of development and the lack of mitigation after the first crash were unforgivable. From an engineering standpoint, the entire model was forced to rely on a single AoA sensor = a single point of failure: a cardinal design sin, as any engineer will tell you. The MCAS was beset with difficulties from the start, but not only did Boeing do little to rectify it, it also actively tried to hide its existence and defend its performance. Company officials also brushed off warnings, played down the dangers of the software, and scoffed at taking additional precautions.

The result? 346 dead bodies. As the daughter of one of the victims of the Ethiopian crash put it:

[It] was corporate manslaughter.”

Hopefully, some lessons have been learnt.


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