Success comes with failure. For America’s largest manufacturer of commercial aircraft, Boeing, has seen its fair share of shakeups. With the recent tragedies surrounding the 737 MAX, the Seattle-based company has faced severe backlash from customers, government officials, and the media alike. Now under intense congressional review and scrupulous regulatory oversight, everyone seems to be seething for accountability from the once highly acclaimed manufacturer. But what has brought this remarkable piece of engineering to this point? Has the Boeing 737 always been the troubled “bird” we know today?

Humble Beginnings

Simplistic design, an attractive purchase price, and pilot-centered operation have made the 737 an appealing aircraft to the airlines. Since its inception in 1964, the twin-engined narrow-body jetliner has become the most successful commercial jet to ever be produced. At least two of the short-to-medium range jets take to the skies every five seconds, globally. Moreover, the aircraft is still in production with 57 rolling off the production line destined for world airlines each month. It has and continues to serve as a reliable workhorse for the global aviation industry.

It all started when the aircraft entered service in 1968 with the German based carrier Lufthansa. The first 737 produced was much different than the technically advanced piece of modern machinery we know today. The original version, carrying only 68 passengers, was much smaller, had less efficient engines, and a significantly shorter fuselage. The stub-like aircraft—nicknamed “Baby Boeing”, predominantly relied upon rudimentary systems which were carried over from previous design, the 727. Airlines had needed something new. An innovative approach to a design that could meet unforeseen future needs with congruent pilot training across later modified versions. An aircraft that was capable of being flexible with the conundrums of industry unpredictability, growing economic pressure, and rapidly advancing technology. More importantly, Boeing needed to diversify its sales—offering an aircraft to its customers with capabilities that its current line up did not have nor could be modified to incorporate. The solution was the 737; a workup of the lessons learned from the 707 and 727 to render a plane ready for the future of modern flight. With each new order, an ambitious founder paved the road for Boeing to lower its bottom line; developing faster manufacturing techniques, better actualizing company processes, and ultimately creating the platform of a wildly profitable international hit.

Early Troubles

Like most aviation companies though, the days of endured success came with “unexpected rough air”. Trouble struck when one of Boeing’s aircraft, a 737-200, operated by Aloha Airlines experienced an explosive decompression on an interisland Hawaiian flight. The Honolulu bound plane suffered a catastrophic failure of the aircraft’s main fuselage structure, ripping away a huge section of the first-class cabin. As the flight climbed to its final cruising altitude of 24,000 feet, the short inter-island commuter blew apart jettisoning one flight attendant from the aircraft and leaving several others injured. The aircraft was damaged beyond repair but was able to safely divert to a nearby airport on the neighboring island of Maui. It was horrific: for the crew; Aloha’s passengers; and moreover, for Boeing. The cause was later found to be fatigue of the outer aluminum fuselage and faults in the airline’s maintenance protocol. While the aircraft had been safely operated for thousands of cycles, Boeing faced criticism of its construction practices. The use of single rived lap-joints; the area where two metal sections of the aircrafts structure overlap, and less than optimal epoxy adhesive, made the structure vulnerable to deterioration due to aging. It led the company to disseminate mechanical warnings to airlines operating the aircraft to correct the problems with more routine inspections and repairs before allowing the plane to continue to operate. It didn’t look good for the now seasoned builder. Boeing later changed its manufacturing processes for its future versions of the 737, incorporating techniques better allowing aircraft to withstand the wear and tear of high-turn operations in addition to changes to mitigate structural aging factors. Despite the changes, it wouldn’t be the only time the 737 hit the news cycle.

Just three years later a rudder control malfunction, congruent in nature to Toyota’s automotive accelerator issue, lead to the crash of United Airlines Flight 585, US Air Flight 427, and near crash of Eastwind Airlines Flight 517. The issue was derived when pilots would descend into warmer air from colder flight temperatures experienced at higher cruising altitudes. As heated hydraulic fluid would enter the super cooled rudder control system (the control surface responsible for maneuvering the aircraft left and right) the control servo mechanism would jam, proceeding then to act in opposition to the pilot’s commanded inputs. The malfunction led to losses of inflight control while aircraft were on approach to landing. Like the issues of the MAX today, it left regulators and the world questioning whether or not to “ground” the problem-ridden versions of the plane. Resolution did; however, come when Boeing was quickly able to re-engineer and provide instruction to operators on how to correct the faulty system. It rendered a short-lived blow to the company’s reputation, but by this point the 737 was an integral asset in airline operations. 737’s accounted for a sizable portion of many carriers’ fleets and an even larger portion of commercial jetliners cumulatively in operation. Profits could not be affected by airlines choosing to change over to a comparable aircraft such as the DC-9. It simply was not operationally viable nor financially possible. “Baby Boeing” was the way of the wise. The customers bit the bullet, even going on to purchase more of later versions as economic recession alleviated its grips on the American airline industry. More importantly, the 737 was still by this time a remarkably safe aircraft with a hull loss rate of only one for every 1.75 million departures, an impressive statistic for the worlds most produced jetliner.

A Modern Issue

Fast-forwarding to 2016, Boeing had built long distance from the days of mechanical malfunction and “bad glue”. By this point the renowned manufacturer had hit their 10,000th delivery of the jet; a record no other airliner in history has yet achieved. The “next generation” of 737s was high tech, incorporating modernized flight decks, fuel efficient engines, and even autopilot systems capable of landing the plane in reduced visibility. Boeing had come a long way. That is at least what they thought until their European based competitor, Airbus, rolled out their newest product—the A320 NEO. Boeing had to edge the competition. Their solution? The 737 MAX—an aircraft with a larger “fan blade” bypass capable of reducing fuel consumption by 20%. It was an enticing pitch to customers, but Boeing engineers faced a unique challenge. With the increased fan blade bypass of the new “LEAP” engines, they were no longer able to fit the bulky engines under the low-sitting 737. This intentional design feature once was a design asset, allowing the original version to sell in less popular markets such as Africa and Asia. The low-sitting fuselage meant that an on-board staircase could be used to allow passengers to board and deplane passengers at smaller airports where conventional terminals or mobile “airstairs” were not available. The once innovative market edge now placed Boeing in a modernization catch 22. How could Boeing make a more efficient engine fit on a 50-year-old blueprint? The solution came in the form of forward mounting the engines by way of pylons on the leading edge of the wings. This had the effect of allowing the engines to sit several inches up and in-front-of the original under-wing position and thus clear of ground obstruction. It was a fix, but it was a fix with a nasty side effect. The re-engineered design now caused a tendency for the aircraft’s nose to pitch up as thrust was added to the engines. The aircraft would not be able to fly safely nor be able to pass rigorous government certification. Boeing needed yet another fix and that fix was MCAS—Maneuvering Characteristics Augmentation System. A computer driven system relying on sensor data from the aircraft’s “Angle of Attack” sensor, a probe which measures differences in aircraft position relative to airflow over the wings. The system would interpret pilot commanded inputs and ultimately render a desired pilot action such as a climb, descent, or turn. The plane would fly just as the pilot intended and more importantly, just like the older versions of the 737 without requiring expensive re-training to pilots already qualified on prior versions of the jet. It was a digitized fix to an engineering problem that Boeing did not have time nor the patience to correct with a “clean sheet” design. They needed a plane to bring to market and fast. Future aircraft sales were at stake.

Then came the crash of Ethiopian Airlines Flight 302, then just four months later the crash of Lion Air Flight 610. Adding two more tragic losses of Boeing’s championed 737. World aviation regulators hands were tied. A line had to be drawn, the most respected of those choosing to ground Boeing’s MAX versions of the aircraft. The suspected core problem later to be revealed as inaccurate sensor data corrupting the MCAS system leading to erroneous computer-activation of the aircraft’s elevator trim system, a flight control used to alleviate control pressures from the pilot during vertical pitch maneuvers. The automation led to, not one, but two fatal nosedive incidents immediately after departure, one being at several hundred miles per hour. The programs reputation, certification processes, and regulatory oversight now were, and are still, under critical review.

These events begin to paint a bleak picture for the 737; they further query a more significant question: what is the future of the 737? As manufacturers rush to maintain a competitive edge in the technical market of aircraft development will the use of non-piloted automation, such as MCAS, continue to lead the way to more advanced aircraft? It is without question that Boeing will continue to strive to stay at the forefront of the pack, more namely its competitor, Airbus. This is the way of free market and industry competition, but will it come at the price of the 737 legacy and future aircraft design safety?

Boeing and the 737 hold a special place in world aviation history and American industrial might. The builder has become the largest aerospace company in the world. Nevertheless, their progress has come with risk—It has been a tattered storyline freighted with challenge, failure, and triumph. From design issues to flight control malfunctions, each disaster has imparted valuable lessons to the ambitious minds which have dared to engineer closer to the precipice of ultimate success or failure. It is with each failure that new systems have been implemented, designs changed, new ideas explored, and innovation paving the way for progress. Like the explosions of the Space Shuttles Challenger and Columbia, disaster is the price we pay to venture the impossible. Boeing’s tattered history of the 737 is a testament despite that same impossibility. A gripping tale of how one American aircraft manufacturer challenged what they already knew about building airplanes to produce a better one. Today, Boeing may have failed with their 737 MAX, but tomorrow’s change is what promises a better-connected world that Boeing continues to make possible. It is the great hope of this author that the legacy of 737 may still live on as a truly beautiful work of engineering the world may soon again trust.