Why did Lion Air Flight 610 and Ethiopian Airlines Flight 302 crash? Was it a pilot error or a problem with the newly designed Boeing 737 Max 8 aircraft?

The Boeing 737 Max 8

The Boeing 737 Max 8 aircraft is the fourth iteration of the company’s 737 fleet. It was designed by Boeing to compete with a similar Airbus model that was more fuel-efficient. Boeing designed the Max 8 with new, larger, and more fuel-efficient engines. Because Boeing placed the engines forward of the wing, the company installed a new electronic system called the Maneuvering Characteristic Augmentation System, or MCAS.

Certified by the Federal Aviation Administration (FAA) in May 2017, Boeing sold 376 Max 8 aircrafts to 54 operators worldwide. The company has received more than 5,000 orders for the Max 8.

Southwest Airlines is one of the largest customers for the Boeing 737 Max 8, with 34 aircrafts in service. Southwest did not ground the fleet immediately following the Ethiopian Airlines crash in March 2019. The company argued that it had accrued more than 88,000 flight hours and more than 41,000 flights without incident. However, Southwest complied when President Trump ordered 737 Max 8s to be grounded.

What Caused the Max 8 Planes to Crash? 

Tragically, all 189 people aboard Lion Air Flight 610 were killed in October 2018, and all 157 including eight Americans were killed in the Ethiopian Airlines crash. Both flights crashed within minutes of taking off. Radar flight data reported variations in speed and altitude before the sudden forward pitch toward the ground.

As of today, both crashes are still under investigation. Early indications suggest an error or failure of the MCAS led to the crashes, perhaps caused by false information or failure of one or more pitch sensors.

The MCAS is an electronic system that seeks to prevent the aircraft from stalling. An aerodynamic stall occurs when the wings stop developing lift. When that happens, the aircraft stops flying. A stall can occur in any altitude; however, a stall is most likely to occur when the aircraft’s nose is pitched up at low airspeed, during which time the angle of attack is too high for the speed. Pitching the nose down reduces the angle of attack and increases air speed.

Pilot experts are concerned that when the MCAS senses upward pitch at low speed, it automatically – and without notice to the pilots – manipulates the controls to push the nose down. Pitching the nose down reduces the angle of attack and avoids the stall.

It is possible that MCAS was activated to pitch the nose down of both the Lion Air and Ethiopian Airlines planes, and before the pilots could react or shut down the system, the aircrafts crashed.

Boeing’s Reaction to the Crashes

Boeing publicly stated that the Lion Air Flight 610 crash was caused by faulty maintenance. It does not appear that Boeing has commented yet on the cause of the Ethiopian Airlines Flight 302 crash.

Boeing noted that pilots should know how to turn off the MCAS. It indicated that perhaps the airline operators decided not to take the time – and loss of revenue – to train pilots to fully understand the MCAS, including how to deactivate the system in the event of an emergency.

Pilots are trained to avoid stalling their aircrafts and have done so successfully for years over millions of flights. It is therefore unlikely that deactivating the MCAS would lead to a stall. Some have criticized Boeing for failing to inform the pilot community of the technology, especially as other iterations of the 737 had no system that would suddenly and automatically pitch the nose down.

Boeing is in the process of issuing an MCAS software upgrade to warn pilots of an angle of attack sensor failure.

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