[panarky]

I don't have data on flight miles or flight segments by type of aircraft, so let's do a quick and dirty estimate.

Let's say there are 40,000 commercial aircraft worldwide and 350 of these are the Boeing 737 Max [0].

If all aircraft are equally likely to crash, then the probability of a given crash being a 737 Max is 350/40000 = 0.00875.

The probability that two crashes are both 737 Max is 0.00875 * 0.00875 = 0.0000766

It's extremely unlikely that an aircraft representing less than 1% of the global fleet would crash twice in a short period of time unless there is a serious defect with that aircraft.

That's well past probable cause at this point. This aircraft should be grounded until they figure this out.

[0] https://en.wikipedia.org/wiki/List_of_Boeing_737_MAX_orders_...

[Steko]

> The probability that two crashes are both 737 Max is 0.00875 * 0.00875 = 0.0000766

You need to multiply this by every combination of two crashes in the observed time period with starting and endpoints not cherry picked to include 737 max crashes though.

[panarky]

Be my guest. You'll find that the probability of a rare aircraft crashing twice in a short period of time is infinitesimal, unless that aircraft contributed to the catastrophe.

[Steko]

It's hardly infinitesmal, that's my point.

With an average of 175 737's operating since launch, 4K total widebody commercial aircraft and over a dozen widebody crashes in that period, you get over 10%. Some estimates there but you still have the endpoint issue as well.

[panarky]

There have been a total of 5 commercial air disasters in 2018 and 2019 with fatalities that didn't involve hijacking, landing short of the runway or overshooting the runway [0].

And that includes the crash of a cargo flight with no passengers where the crew was killed.

The 737 Max 8 was involved in 2 of those 5 disasters.

There are between 25,000 and 39,000 commercial aircraft in service depending on who you ask [1].

With 350 737 Maxes delivered so far, that's at most 1.4% of the total today, probably less than half that this time last year. Let's call it 1% on average for 2018 and 2019 combined.

There are 10 ways you can have 2 Max crashes out of 5 total crashes. So the probability is 10 * 0.01^2 * 0.99^2 = 0.00098

Even accounting for n choose k and longer endpoints, it's still an infinitesimal probability that we'd see two catastrophes with the same rare aircraft -- unless that aircraft contributed to the catastrophe.

It should be grounded.

[0] https://en.wikipedia.org/wiki/List_of_accidents_and_incident...

[1] https://www.telegraph.co.uk/travel/travel-truths/how-many-pl...

[markdown]

Active fleet today: https://twitter.com/flightradar24/status/1104838043792490497