Crashed Boeing 737 Max 8 Lacked Safety Features: They Cost Extra?

by Bill Shuman

Boeing is the first to tell airlines, investors, and passengers that safety is their first priority when designing an airplane. However, findings from a New York Times report indicate that the Lion Air and Ethiopian Airlines 737 Max 8 were lacking safety features. The reason behind the lack of safety sensors? The airlines didn’t pay for the optional upgrades.

The Components in Question

The cause behind both crashes remains undetermined. However, it appears that one of the safety features on both planes is being called into question. The device’s name is the Angle of Attack (AOA) sensor. This sensor measures the angle between a plane’s wing and the direction of the air. This crucial data determines whether a plane has enough lift.

The Boeing 737 MAX contains a computerized system known as the Maneuvering Characteristics Augmentation System (MCAS). The MCAS detects when the plane is pointing up at a dangerous angle and assists by pushing down the nose of a the plane to prevent a stall.

On the 737 MAX, airlines had the option to purchase two upgrades related to the AOA sensor. The first safety feature is the AOA indicator that displays the AOA information in the cockpit. The second, labeled the disagree light, activates when the information from the two AOA sensors aren’t in agreement.

Are These Sensors Required?

Sadly, no. The Federal Aviation Administration (FAA) has not made either of these sensors mandatory. In fact, all three of the US carriers approached the purchase of these upgrades on the 737 MAX differently.

  • United, which had 14 MAX planes in service of the 137 ordered, did not purchase either upgrade.
  • American Airlines, which had 24 planes in service out of its 100 ordered, purchased both.
  • Southwest, with 36 planes already flying out of 280 ordered, initially purchased the disagree light. Then after the Lion Air crash, Southwest took a proactive measure in December of 2018 by adding the AOA indicator to the pilots’ main computer screens.

What Boeing Will Do Moving Forward

According to the NY Times, the MCAS system will be updated by Boeing. In the initial release, the MCAS system only gathered data from one sensor. In the upcoming software update, it is reported that the MCAS will be modified to take readings from both sensors and that if the sensors disagree in the readings, the MCAS will be disabled. Boeing will also make the disagree light standard.

The Upshot

Bjorn Fehrm, an analyst at aviation consultancy Leeham said,

[The sensors are] critical, and cost almost nothing for the airlines to install…Boeing charges for them because it can. But they’re vital for safety.

Customers are used to paying for extra features, like in our cars for example. To me, this raises the question of where companies and government agencies draw the line between what is required and what should be optional. Personally, as an airline passenger, I don’t think a safety component should ever be optional, but maybe that’s just me.


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James H March 22, 2019 - 2:10 pm

Another real factor: pilot info overload. The Ethiopian pilots KNEW about the problem with MCAS and (supposedly) how to deal with it…yet it may turn out that they didn’t react based on that training…which would have saved the plane. Boeing and airlines can put out all the technical details they can…but it still comes down to the pilots.

Bill Shuman March 22, 2019 - 2:50 pm


Absolutely! I cannot even begin to comprehend how much information pilots have to process during a flight. Let alone during an emergency and I’m a teacher for elementary students who makes thousands of decisions a day. My hope is that pilot training increases on the system and all of the safety components so they are comfortable with the new systems. I also hope that all of the safety features are included with each plane that gives the pilots as much information as they can in real time to make the best decisions that they are able too.

Gizmosdad March 22, 2019 - 6:47 pm

I used to develop medical devices. It is common practice to have redundant sensors and software algorithms that checks to see if what the sensors are saying make sense. There is no extra charge, and this isn’t an optional feature, because we know that sensors can fail, and it just makes sense to do sanity checks on vital pieces of information.


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