The Boeing 737 MAX, a QA perspective

Thanks to: Wikipedia.org user Acefitt

The Boeing 737 MAX and its MCAS system (which tries to emulate the handling characteristics of earlier generations of the product) have been in the news a lot lately. Investigations are still ongoing, but the product is being blamed by many for two crashes which have resulted in the loss of almost 340 lives.

That's a big quality problem. Clearly, the pressures on the Boeing are immense. The worldwide commercial aircraft market is over $191 billion, and dominated by cut-throat competition between Boeing and Airbus.

The 737 has been in production since 1967, and if you are a pilot who was qualified to fly it in 1967, you still are today, despite vast numbers of changes to the aircraft. This is because Boeing has managed to keep the aircraft handling similar enough over time that the FAA (and other worldwide governmental authorities) has been willing to allow the "type certification" of pilots to be valid for all variants of the product. The current version of the product uses the "MCAS" system to try to keep the handling as similar as possible to older versions, despite much larger-diameter engines being used on the current model.

The very existence of the MCAS software indicates that Boeing was aware of handling differences in the new aircraft, and was working to overcome them. Were the requirements and tests for the MCAS software good enough? Was it a failure of the software to perform up to the spec, or was the spec insufficient in the first place?

There's clearly a lot of investigation going on, and it's certainly no longer restricted to QA staff on the Boeing side, but a few interesting questions stand out, and I'm sure the ongoing investigations will be trying to turn up answers.


  • Did the software fail to meet the spec, or was the spec weak in the first place?
  • Who at Boeing thought there were problems?
  • What did they do to escalate them?
  • Were these reports stifled or swept under the rug? By whom? And for what reasons?
And at some point, probably after the news has stopped paying attention, they will need to turn their attention to the penultimate step of the 8D process, "Prevent recurrence!" 

It is in some ways the least a quality organization can do, but also profoundly important.

Make sure it never, ever happens again.

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