The Boeing 737 MAX 8 is getting a lot of bad press at the moment, but people's instincts when it comes to probability are generally terrible, especially when it comes to risk assessment.

Compared to other models, how unusual is it for there to be two crashes in half of a year, of rather young planes? How much total flight time has the model had? How statically signification is it?


Historically, it's not unusual at all to have many accidents of an aircraft type in relatively short order, especially when the type is still new and hasn't had a lot of operating hours across the fleet to detect and work out teething problems.

BUT, and that's a big BUT, in recent history that's been happening less and less as testing and certification programs have gotten ever longer and stricter (in large part as a result of those earlier crash series).

As for the 737Max, according to Wikipedia some 350 have so far been delivered (out of over 5000 on the order book) over the space of only 2 years (yes, they're that new). Of those 2 have gone down. That's not a particularly high number historically, but as said in recent history people have come to expect nothing bad to ever happen because there have been so few accidents overall and most of those easily explained by external factors (MH17 being shot down, for example).

So this number is both highly unusual, in that it's not something that's been seen in recent memory, and rather normal, in that in the history of aviation it's not unusual at all.

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    $\begingroup$ "Highly unusual.. and rather normal" Nice summary! $\endgroup$ – FreeMan Mar 13 at 13:08
  • $\begingroup$ So, 2/350 ~= 0.5% crashes is "not a particularly high number"? I realize that's not 0.5% of flights, but still. Are you sure? $\endgroup$ – einpoklum Mar 14 at 9:41
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    $\begingroup$ @einpoklum it isn't, historically. Extreme case is Concorde, with 1/14 crashes or about 12%. Out of about 700 DC-6s 185 were lost or over 26%. Tu-154 had about 1000 built and 69 hull losses, or about 7%. I just count hull losses here. So no, the number is in no way particularly high. It's only more than a statistical blip because both losses happened in under 2 years since the type entered service. $\endgroup$ – jwenting Mar 14 at 11:15
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    $\begingroup$ @jwenting: Within 2 years... $\endgroup$ – einpoklum Mar 14 at 13:31
  • $\begingroup$ @jwenting: Actually, an "extreme case" would be the de Havilland Comet 1/1A - 7 hull losses out of a total of 22 produced (32%), all within a year and a half (26 October 1952 - 8 April 1954). $\endgroup$ – Sean Apr 4 at 0:16

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