*Boeing 737 Max aircraft grounded at the Boeing Field in Seattle

Developments in Aviation

The aviation industry has been rapidly evolving. Ever since the Wright Brothers developed the first successful powered airplane - The 1903 Wright Flyer, to multi hundred-million dollar machines. The industry is constantly trying to improve on one aspect or the other, to make flying more affordable and sustainable. But in the process, some or the other aspect does get compromised. Lets see how one of the pioneers of commercial aviation nearly lost the trust of the Pilots Union, and millions of loyal passengers. 

Airbus vs Boeing - An Old Rivalry

With globalization taking place and fuel costs rising came the need to make more sustainable and fuel-efficient aircraft. To do so, two major aerospace companies took the job. Netherlands-based company Airbus and Arlington-based(then Seattle-based) company Boeing. The job - to engineer sustainable, fuel efficient and safe aircraft.

Airbus and Boeing have a fierce rivalry in the aviation market, constantly competing for new orders and customers particularly in the "narrow-body" segment of commercial aircraft. Airbus has a slightly higher market share thanks to the solid sales of its A320neo family of aircraft.

The A320neo is a new version of the A320, introduced in 2016. "NEO" here stands for "New Engine Option". Airbus marketed this aircraft as 15% more fuel efficient than today's comparable models. Thanks to its new, larger engines and improved aerodynamics. 

*Differences between the A320 and A320neo

Seeing that they could fall off the market with the introduction of this aircraft, Boeing had to strike back with an exceptionally-engineered aircraft to compete against Airbus.

Boeing's Answer - The 737 Max

Boeing introduced the 737 Max - a new version of the 737-800 series to compete against airbus in the narrow-body aircraft market. Boeing said - "The 737 MAX delivers enhanced efficiency, improved environmental performance and increased passenger comfort to the single-aisle market. Incorporating advanced technology winglets and efficient engines, the 737 MAX offers excellent economics, reducing fuel use and emissions by 20 percent while producing a 50 percent smaller noise footprint than the airplanes it replaces. Additionally, 737 MAX offers up to 14 percent lower airframe maintenance costs than the competition. Passengers will enjoy the Boeing Sky Interior, highlighted by modern sculpted sidewalls and window reveals, LED lighting that enhances the sense of spaciousness and larger pivoting overhead storage bins." But nothing could be further from the truth.

To make the aircraft more fuel-efficient, Boeing implemented much larger engines, a larger wingspan and a higher maximum take-off weight than its predecessor - the Boeing 737-800. While planting larger engines underneath the wings might sound easy and ideal, it is quite the opposite. Planting larger engines and increasing the wingspan hinders with the aerodynamics of the aircraft. Erroneous movements, increased drag and most importantly, reprogramming the computers on the aircraft, which are used by pilots to program the auto-pilot.

*Differences between the 737-800 and 737 Max

Boeing's Marketing

Boeing marketed the 737 Max as a direct replacement to the 737-800. It passed all the checks carried out by the Federal Aviation Administration and was rendered "aerodynamically stable". With the aircraft being a direct replacement to its predecessor, Boeing said that existing pilots did not require full-fledged simulator training sessions to get used to the controls and aerodynamics of the aircraft. Instead, pilots took a two-hour training course on an iPad. However, that was not the underlying issue.

Accidents

29th October 2018: Lion Air Flight 610 was a scheduled flight from Jakarta, Indonesia to Pangkal Pinang, Indonesia, operated by a 737 Max. The plane operating the route crashed into the Java Sea, 13 minutes after take-off, killing all 189 passengers and crew - the first fatal accident involving the new 737 Max aircraft.

10th March 2019: Ethiopian Airlines flight 302 was a scheduled flight from Addis Ababa, Ethiopia to Nairobi, Kenya, operated by another 737 Max aircraft. The aircraft operating the route crashed near the town of Bishoftu, 6 minutes after takeoff, killing all 157 poeple on board.

Two fatal accidents within a span of 6 months. Two hull losses and 346 deaths.

The Aftermath

Thorough investigations were carried out in Nairobi and Jakarta. Boeing officials were also called to aid with the investigation. Every single parameter was examined. From the communication between the pilots to the data of the various instruments of the aircraft. One parameter stood out - the altitude readings. It was a graph which showed many quick fluctuations. This was the case in both the accidents. 

*Lion Air 610 altitude chart

From the chart it is observed that the aircraft kept on ascending and descending continuously by itself. What could be the cause? Could it be manual input from the pilots? Or could the aircraft be aerodynamically unsound?

Boeing's Secret

Upon thorough interrogations with Boeing engineers, investigators came to know that a software called MCAS (Manouvering Characteristics Augmentation System) was the reason for such erroneous altitude readings. It was a software desgined to counter the aerodynamics of the aircraft. During the marketing phase, Boeing had not said anything about implementing such a system. Neither airline nor pilot knew such a system existed on the aircraft. What was special about the software that Boeing did not reveal to the pilots? Could it be THE reason for 346 deaths?

Fatal Design Flaw

When designing the 737 Max to be more fuel-efficient, Boeing had to mount larger engines underneath the wings. Airbus had done the same to the A320neo line. Why did Boeing's move fail when they implemented the same idea as Airbus did? Turns out that the standing vertical height of the 737 Max is much lesser than the A320neo, therefore the ground clearance of the 737 Max is significantly lesser than the A320neo. 

*Depicting the height difference between the aircraft
Left - A320neo, Right - 737 Max

Though this may not be a significant height difference, it did hinder with the aerodynamics of the 737 Max. Due to lesser height, Boeing engineers had to advance the engines under the wings, so they could be positioned higher. This hindered with the angle that the wings made against the air. This is known as Angle of Attack (AOA). The mounting of the engines altered the flow of air under above the wing, resulting in a higher angle of attack. 

If the angle of attack is too high while gaining altitude after take-off, it can result in an aerodynamic stall, which is a speed so low that the aircraft cannot sustain flight.

*Angle of attack with respect to the horizon

Boeing's Solution - MCAS

*Demonstration of MCAS

Engineers observed a tendency for the plane’s nose to pitch upward as a result of higher AOA. After other efforts to fix the problem failed, the solution they arrived at was a piece of software -  the Maneuvering Characteristics Augmentation System (MCAS) - that would move a powerful control surface at the tail to push the airplane’s nose down. The MCAS played a critical role in two airliners nose-diving out of the sky, killing 346 people in Ethiopia and off the coast of Indonesia. Neither pilots nor airlines were aware of the existence of such a system. 

Boeing's Reputation

According to the Indonesian findings, MCAS relied on only one sensor, which had a fault, and the flight crews hadn’t been well trained in how to use it. Also they said: There was also no cockpit warning light; the Lion Air pilots were unable to determine their true airspeed and altitude as the plane oscillated for nearly 10 minutes; and every time the pilots pulled up from a dive, MCAS pushed the nose down again, horribly. Boeing was largely to blame as they expected the pilots to react within three seconds of the erroneous movements. Boeing grounded the entire fleet of the 737 Max to work out a solution to tweak the MCAS. As of today the 737 Max series is back in service. Due to mergers with McDonell Douglas in 1997, Boeing had an already fragile reputation due to switching of various managerial roles. These two accidents cratered Boeing's reputation. Boeing agreed to pay $500m to the families of those who lost their loved ones. Boeing has come a long way from its reputation of "If it's not Boeing, I ain't going".