[wat10000]

The article says that a risk analysis was done for the system and the risk was found to be “extremely improbable,” meaning between 1 in 100 million to 1 in a billion flight hours.

This flight may have been extremely unlucky, or the risk analysis may have been wrong. This is why the behavior of the Egyptian authorities is so frustrating; the purpose of the accident investigation is to see if there are problems that should be addressed.

[CamperBob2]

Also, even if the risk analysis was right, it didn't justify an "extremely improbable" conclusion. If the global airline industry operates a total of about 50 million flights per year, and the average duration is about 2 hours, then we stand a good chance of seeing an accident like this every few years.

[wat10000]

Reading up a little on the regulations, the FAA defines “extremely improbable” as less than one in a billion per hour, with the goal that a given type of airplane should be unlikely to ever experience a catastrophic failure during its service life.

Of course, there’s more than one type of airplane in the world, so you do have to wonder if that standard is adequate. I didn’t see how they quantify “unlikely,” but if it’s, say, 1 in 10 then the wide range of aircraft types means many of them will experience a catastrophic failure.

I’d expect this stuff to be gradually tightened. The current standard would have been ridiculous and unobtainable some decades ago. As technology and experience advances, there should be room to improve it further.