The Boeing 737 MAX is a plane with a troubled safety record. Less than a year after its release, on October 29th, a two-month old 737 MAX crashed soon after departing Jakarta in Indonesia. Almost five months later on March 10, Ethiopia Airlines ET302 crashed six minutes after takeoff from Addis Ababa. China and the rest of the world grounded the 737 MAX fleets, a measure which airlines expect to last at least until January 2020. As we approach the 11th month after the first crash, we will provide an account of what decisions led to these accidents, and what the impact of these events and the investigators findings are.

In 2011, Airbus began selling its A320neo, a single-aisle cost efficient plane. Boeing, which didn’t have plans for a plane with similar advantages to the A320neo, rushed into the development of their jet. The deals that Boeing had made with companies emphasized that the 737 MAX would easily fit in with their existing 737 fleet, requiring no additional necessary pilot simulator training. The reasoning behind this would reduce the costs of adopting the MAX into existing fleets for the various airlines. In line with this concept of reducing costs was the change to add larger, fuel efficient engines.

But there was one problem. Adding the larger engines to the frame caused the planes nose to tilt upward at high altitudes, increasing the risk for a stall; a state in which the lift generated by the wings is disrupted, causing an affected plane to fall from the sky. Changing the frame too much might cause the Federal Aviation Authority to require simulator training, so instead of changing the weight distribution, the engineers opted to create the MCAS, the Maneuvering Characteristics Augmentation System, which would automatically adjust the plane’s stabilizers to point the nose down in the event that it pitched too high.

The addition of MCAS is a prominent example of Boeing’s changing design philosophy. Boeing typically has distinguished itself from Airbus by avoiding implementing automated systems which take control from the pilot. Pulling up on the planes control column, for example, normally cuts power to a runaway stabilizer, giving the pilot more manual control. While MCAS is active, however, pulling up on the column does nothing, a change which might catch regular 737 pilots off guard.

At first, MCAS seemed to be the perfect simple solution. The chance of the MCAS failing or malfunctioning was deemed low. Even in the eventuality that it did, pilots would have enough control to correct the error. As a result, only one sensor was required. The procedures to follow in the event of a malfunction were similar to a more common problem, a runaway stabilizer, so no new training would be necessary. They sent a safety assessment to the FAA, and the FAA approved with their assessment of MCAS. No information about MCAS was provided to pilots, as it was not considered necessary for them to know about it.

However, after the system was approved, a few additional changes took place that the FAA was not made aware of. In an attempt to comply with FAA regulations relating to flight control, the MCAS had its maximum stabilizer deflection increased from 0.6 degrees to 2.5 degrees per activation. The FAA did not require a revised assessment for that type of flight system, so Boeing did not send them.

A minority opinion among people is whether the pilot training standards were rigorous enough. U.S. pilots pilots and copilots must have at least 1,500 hours of training, while international standards require only 250 hours of training. Having forgone simulator training, Boeing had only an hour long course for pilots on the changes between the 737 and the 737 MAX. This has been criticized by pilots and others, but poor training is not considered to be a primary cause of the accidents by most sources.

The two crashes were fairly similar in their composition of events. Both the Ethiopian and Indonesian flight crashed soon after takeoff, after the sensor controlling MCAS malfunctioned, or in the Ethiopian flight’s case, was likely destroyed. MCAS fires repeatedly and forces the nose of the plane down. This causes several additional warning alarms, making it more difficult for the pilots to identify the problem quickly. Both crews struggle with their controls before losing control of their planes and crashing. In all, 346 people have died as a result of the crashes.

In the aftermath of the crashes, all 737 MAX planes were grounded. This has caused a lot of disruptions for the airlines who have bought the MAX, who are unsure when the plane will be returned to service. As Robert Isom, president of American Airlines noted, this year “should have been much better for American”. As a result of this, fewer of the 737 MAX planes have been sold, creating a potentially troubled future for the MAX and Boeing. Boeing’ is large and important enough to sustain losses in the short term, and should survive this event.