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0 pointsprivong7y ago0 comments

> So 20 MAX-related issues out of ~850. How is that significant?

To build on what @ggm and @siwatanejo noted. The 737 debuted in 1967, so it is 52 years old now. The 737 MAX is 2 years old. In terms of number of issues per year since the aircraft was introduced the 737 is at ~15 incidents per year and the 737 MAX is at ~10/year. But as @ggm notes, it's important to look at when in the life cycle many of the non-MAX 737 incidents occurred.

Another way to look at this is by number of aircraft produced. The Boeing website[0] gives production numbers for various classes of the 737. In terms of incidence per number of aircraft delivered the non-max 737s have 0.082 incidents per delivered aircraft while the 737 MAX has 0.05 incidents per delivered aircraft.

Both of those suggest that the 737 MAX may not be any worse than the non-max 737s, but a more careful statistical analysis is probably necessary to draw strong conclusions.

[0] http://active.boeing.com/commercial/orders/displaystandardre...

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ansy7y ago

I’d look at incidents per flight hour. Some of those 737s have been in the air for decades. I suspect the numbers for the 737 MAX will stand out more on this analysis.

close047y ago

It’s also worth noting that the MAX should benefit from 5 decades of accumulated experience and regulation. So you’d expect far lower incidents.

The problem might not be with the plane per se but rather with Boeing rushing a bit and relying on the fact that “it basically the same plane but better so why would there be issues”.

tziki7y ago

Note that 15 vs 10 incidents per year is also not accurate since there are far fewer 737 MAXs out there.

cobookman7y ago

It's likely that a given plane gets more incidents at the start of its life. It might not be statistically significant

dajohnson897y ago

So then why did I get downvoted so hard?

privongOP7y ago

I didn't downvote you, so I can't speak for those who did. But I replied because simply saying "20/850 is small" isn't sufficient to argue there isn't a difference between the two planes. Partly because the timescales for the two incident counts are different and so are the number of planes constructed. So normalizing the incident counts against those quantities is a first step at getting towards their significance. Though as @ggm and @ansy point out, the incident rates also vary as a function of time through the lifetime of that airplane model. So really that behavior needs to be examined as well.

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