[pc86]

As the sibling comment says the NTSB doesn't investigate crimes, and you don't need to wait for an NTSB report to believe their could have been criminal negligence, or to being an investigate into that.

If someone was negligent and caused this accident and these deaths, they should be held accountable. That will keep people in similar positions in the future more likely to be honest and accountable, not less. You don't avoid prosecuting crimes on the off chance it will make criminals more likely to lie about being criminals.

[lazide]

'Blameless postmortem' requires people are able to discuss things without being blamed.

If they are (or are likely to be) being criminally prosecuted, being completely candid would require they'd have to be idiots or so clearly innocent of wrongdoing even the most cynical lawyer thinks it will be fine.

Even if someone tries to falsify evidence or frame their client.

Which everything being easy and fine is not very likely, frankly.

Especially when a bunch of pissed off commuters and taxpayers are pressuring politicans, families are looking for compensation for dead relatives, and you're front page news globally - with damages running in the hundreds of millions at a minimum.