Max Limit, Max Damage: The Boeing 737 MAX

You may have heard of the 2 crashes related to the Boeing’s new narrowbody plane on the market, the Boeing 737 MAX. However, the plane isn’t exactly new, rather it is a modern redesign of a plane that is more than 50 years old. The Lion Air 610 crash on October 29, 2018, and the Ethiopian Airlines crash on March 10, 2019, which resulted in the deaths of 356 people combined, led to much doubt over Boeing’s safety certification of the plane and the grounding of all the Boeing 737 MAX planes worldwide. Many pointed to the 737 MAX’s flawed MCAS (Maneuvering Characteristics Augmentation System), intended to counter aircraft stall, that is widely believed to have caused issues for the pilots mid-flight, even forcing the plane into a dive. How did it ever come to this point? Why did such a modern plane made by such a renowned aviation manufacturer become so deadly? First, we must look at the 737’s history to fully understand Boeing’s mishap.

In the ’60s, Boeing saw the market potential for a small regional jet that airlines can use to service small airports, giving rise to the 737. The first 737’s were introduced to commercial service on February 10, 1968, with German airline Lufthansa. Introduced as the 737-100 and the longer 737-200, they were designed as short range and low capacity jets to service small and undeveloped airports in an airline’s network, allowing more routes to open up and more paying passengers to fly. Boeing took the restrictions of regional airports in mind with their 737 design, going with a short fuselage that was closer to the ground to ease up maintenance, allow baggage handlers to manage luggage by hand, and make boarding and deplaning easier for passengers with its own metal staircase. The engine chosen to power the plane was the Pratt & Whitney JT8D, which was much longer and thinner than most other engines, allowing Boeing to fit the engine under the 737’s wing. The 737s proved to be a fuel-efficient and popular choice for many airlines around the world.

As the years passed, Boeing needed new and even more fuel-efficient planes to compete with other place manufacturers, most notably Airbus and their new Airbus A320 family of aircraft that directly challenged Boeing’s 737. At risk of losing customers, Boeing chose to redesign the 737 as a much cheaper and quicker way to get a new plane out to the world in time to prevent Airbus from getting a market foothold. They released the 737 Classic series in 1979 (-300, -400, -500) and the 737 Next Generation series in 1991 (-600, -700, -800, -900ER), the latter specifically the counter the Airbus A320. New improvements involved glass cockpits, modern passengers cabins, larger capacity, longer range, and most notably a newer engine. For both the 737 Classic and Next Generation series, Boeing chose the newer CFM International CFM56 engine. It was larger than the JT8D and initial problems showed the CFM56 to be too large to fit under the 737’s wing. Boeing easily got around this problem by moving the engine forward and creating a ‘hamster pouch’ to reduce the engine’s radius toward the ground. All seemed well for Boeing as up to that point they sold their 10,000th 737 on 2012, while passengers and airlines all over the world praised the 737 for its easy maintenance and passenger comfort.

Soon, however, Boeing faced their next big challenge. Their main competitor, Airbus, announced that they would re-engine the a320 into the new A320neo in 2010 with the new CFM International LEAP engine, promising airlines fuel-efficiency like never before. Since then Airbus has gotten 6500 orders for the series type and today have delivered 778 of them. Boeing needed a quick way to compete against the A320 neo, so their best idea was to re-engine the 737 once again. Although Boeing also wanted to use the CFM International LEAP, it was much bigger than the CFM56 and seemed impossible to fit under the 737’s wing. Perhaps instead Boeing should just design an all-new plane with a clean sheet design? No, it wasn’t plausible at the moment, as a new plane needs decades to design and manufacture and pilots need new training to use them, which could give Airbus an open and dominant a320 market for an extensive amount of time. Airlines also needed a plane that was cheap and quick to acquire, not as fuel efficient as a completely new aircraft would bring, since the 737 was designed to stay in the air for less time each flight. As such, Boeing was stuck with a re-engined 737.

Boeing’s engineers had a breakthrough, however, as they pushed the engine up and angled it higher so that it would still fit under the 737’s wing. Add on some cockpit, winglet, and cabin upgrades and Boeing had a brand new plane to sell, the 737 MAX, which included the -7, -8, -9, and -10 variant. Boeing sold around 5,000 planes with 393 having been delivered today. The MAX became Boeing’s best selling airliner in the company’s history since 1916. Airlines loved it, passengers praised the modern cabin and seats, and the global media covered Boeing’ success. Finally, Boeing could still effectively compete with Airbus in the narrowbody market, but new issues arose.

After the Lion Air and Ethiopian Air crashes, many pointed to the MCAS system as the main causes of the crash. Boeing installed the MCAS because the higher engine placement of the CFM International Leap posed a higher risk of aircraft stall, where a plane hits an angle where it is no longer producing enough lift to fly, forcing the aircraft to plunge to the ground. The system’s greatest flaw was its lack of redundancy caused by the use of only one sensor to detect the stall. This meant that if there was a failure, as seen with Lion Air and Ethiopian Airlines crashes, the system would correct in a way that pilots couldn’t counteract.  In addition, pilots were unable to turn off the system. This flaw stemmed from Boeing’s main selling point to airlines, since they promoted the 737 MAX as having virtually the same controls as the previous 737, so airlines did not need to spend more money and time on training pilots to be certified with the aircraft type. However, this meant that many pilots did not know about the MCAS system at all, much less how to control it. Airbus did not face such an issue because their A320 is inherently taller than the 737, so the new engine could fit under the A320’s wing without any need for placement adjustments like the 737.

So where does Boeing go from here? With the 737 MAX grounded worldwide and its reputation among airlines and passengers alike ruined, the company seems to have a bleak future ahead of it. Boeing is already working on software updates to fix the MCAS and include a section in the aircraft manual for pilots to know how to operate the MCAS. Boeing will continue to manufacture the 737 MAX but until the grounding order is lifted they cannot deliver the planes, resulting in a crowding issue for many new but unused 737 MAXs lying around in Boeing’s Everett Factory in Seattle. Boeing hopes that the 737 MAX can receive  FAA certification as a new plane, and see the 737 MAX return to service sometime later in the year. The 737’s principle designed has reached its peak, and for future regional jets, Boeing will need to look to a long development cycle and a clean sheet design to prevent such a disaster from occurring again.