Airline Industry Overview

Commercial Airplane manufacturing industry is mostly a duopoly between Boeing and Airbus for many years now after lot of consolidation that happened. Erstwhile USSR had Antonov and recently Chinese company Comac has been trying to develop C-919. But largely the duopoly has existed and both the firms wants the status quo.

There are other aircraft companies in the smaller aircrafts Bombardier, Pilatus, Cessna, Dassault,Fokker, Gulfstream, Embraer and other. The markets they play in are different.

Airbus had upgraded their A320 to A320 NEO (New Engine Option) which promised to give cost savings to the airline companies based on new improved bigger engines. Boeing also had a 737 NG but it needed something else to counter Airbus and 737 Max was the answer.

Things were going fine for 737 Max until two crashes Lion Air Flight 610 and Ethiopian Airlines Flight 302 killing 346 people onboard leading to the grounding of all 737 Max globally by FAA.

Causes of the failure and the proposed fix for 737 Max

Recently FAA had completed its analysis of about 22 months after it had ordered grounding of all 737 Maxs around the world. The Angle of Attack (AOA) sensors were giving erroneous readings that activated a very specific software designed for 737 Max called Maneuvering Characteristics Augmentation System (MCAS) that is  a flight control law implemented on the 737 MAX to improve aircraft handling characteristics and decrease pitch-up tendency at elevated angles of attack.

But with erroneous high AOA signal MCAS goes into loop in every 5 seconds airplane nose-down stabilizer trim command making the aircraft very unstable making it difficult for the crew to take full control.

In the case of Lion Air 737 Max it was also found that AOA sensor was repaired but calibration was not done properly leading to a bias in sensor readings further complicated things for the crew.

MCAS software that was supposed to work only after a threshold was exceeded for angle of attack signal and flight should be in manual control and flaps fully retracted. In both the Lion Air and Ethiopian Airlines crash, the aircrafts were taking off and met all required conditions for MCAS to get activated.

The fix that is being proposed is going to take sensor data from two AOA sensors that are already there in aircraft. Boeing initially used only one during a flight and changed alternately. Enable MCAS only when both the sensors agree. MCAS will no longer be able to go into a loop but will command only one horizontal stabilizer for each high AOA event. There will be additional information displayed on displays in cockpit if the Angle of attack sensors don’t agree. There are other updates to training and checklists including MCAS details.

What can be the learnings for product development?

Boeing 737 has been a very successful aircraft and has been flying for decades now with incremental changes. And lot of respect is given of the aircraft design, system design, algorithms and software that have been flying for years. Boeing when decided to not start a fresh new model but incrementally modifying 737 NG to make 737 MAX, engineers were instructed to keep the aircraft similar to 737 NG leading to less or no training for the pilots who are already flying 737 for ages. There is such a huge legacy which is very beneficial for all stakeholders if not changed. Also time to market was very important as Airbus was now getting orders from important Boeing Customers.

Due to the aerodynamic changes to the 737 MAX and in order to meet some of FAA guidelines, Boeing developed MCAS control algorithm which was deemed small enough changes by the management which can be easily countered manually. Hence Boeing deemed it fit for having no training of the MCAS control algorithm for the pilots and there was no mention of it in the documentation.

Companies like Boeing has such a great legacy and will know much more about designing reliable and robust systems that almost anyone else. These days many companies are outsourcing work that the management thinks to be non-core and not a great value add. This is one of the reason that creates the blind spots for a larger company like Boeing when an aircraft have hundreds on systems with a supply chain that staggered all across the world.

Time to market and releasing a product on a certain date at a certain cost is leading in too much pressure on engineering teams to deliver.

There were days when best technical minds would be drawn to companies like Boeing and lure of developing flying machines was a great pull. In today’s world when there are other avenues to grow one’s career than getting into developing products like 737 would take years and maybe working lives of many. This has become less enticing for engineers who can do a lot of other things and make great careers.

In the pursuit of outsmarting the the competitions and making profits the engineering decisions needs to thought through and teams needs to be empowered and listened to.

Refrences:

FAA Link and various reports

Report of Indonesian Authority KNKT

David Perrel’s Essay on 737 Max Crash

Boeing Company Page on SW updates