[nradov]

What about the unknown bugs that could lead to deaths? I guarantee that every modern aircraft has some. But we don't know how many.

[mehrdadn]

> What about the unknown bugs that could lead to deaths?

I wouldn't include that since it wouldn't be useful. In any case it clearly wasn't included in whatever definition the top commenter intended.

[slededit]

You would be incentivizing them to not look very hard as finding a bug would ground the fleet and be extremely expensive. The same way a lawyer will tell you never to see if your violating a patent lest you pay treble damages for "knowing".