The details are nuanced by the definitions in the CFR, the details of the reporting requirements (NTSB must do something with everything reported to it but that may be minimal), and the NTSB's authority to delegate more minor investigations to FAA flight standards. Lots of people in the thread are hashing these out. But it suffices to say that when an airplane is seriously damaged or people are seriously injured, the NTSB is obligated to investigate. This dates way back to before the NTSB existed. In straightforward situations that sometimes consists only of the regional office making some phone calls and then preparing a two-page summary (you see a LOT of these two-page summaries for GA incidents, it's basically a form letter), but that's under the assumption that their cursory review doesn't turn up anything interesting. You can already find this incident in the NTSB's investigation database, WPR22LA049.

Yeah, parent commenter has no experience in any aviation matters. I've been in a "crash" (off runway excursion, no injuries, no damage save a slightly bent landing gear door flap.)

The "investigation" consisted of the airport director speaking with the PIC and passenger (me.) His sole question to me was "were you operating the aircraft?"

There are a lot of stories of pretty terrible decisions made by GA pilots and little/nothing happening from the FAA. And then do stupid shit like going after Bob Hoover's license because he was too old for their tastes.

Not every aircraft crash is an aircraft accident.

The definition of an aircraft accident is a matter of federal law: https://www.law.cornell.edu/cfr/text/49/830.2

An aircraft crash where the aircraft suffers minor damage and no one is seriously injured is, by definition, not an aircraft accident, but rather an incident. (This incident is definitely an aircraft accident, of course, whether or not it was accidental. :) )

There is prior art for non-accidental plane crashes: https://www.youtube.com/watch?v=LhoxaJTzPu4

Thanks for the clarification of terminology. "Crash" is indeed a bit ambiguous as a layman's term (though I would personally argue that incidents that cause minimal damage are generally not considered crashes.) Indeed, I think there are even many accidents that don't rise to the level of what I consider a crash (such as when my dad's friend bent a prop by briefy tipping his plane onto its nose when landing on a gravel bar to pickup a load of the moose they had killed. While they did fly it out by cutting/sanding all the prop blades to match and reducing weight, it would seem to easily match the definition of "significant damage" but I still wouldn't call it a crash.)

I believe the claims made by the GP are still clearly wrong, given that they do use the term "accident" and stipulate criteria for investigation that (commercial or passengers) that have no basis in the definition your provided or the NTSB's mandate.

> While they did fly it out by cutting/sanding all the prop blades to match and reducing weight, it would seem to easily match the definition of "significant damage"

Probably not (assuming you're trying to determine reporting requirements and figuring out if it's substantial damage). It's specifically excluded: "ground damage to rotor or propeller blades, and damage to landing gear, wheels, tires, flaps, engine accessories, brakes, or wingtips are not considered “substantial damage” for the purpose of this part." The NTSB doesn't want to be bothered everytime a prop makes ground contact, hits a runway light, a towbar, etc. It happens a lot.

In most countries, depending on severity of the event, the agency responsible for crash investigation can delegate investigation of the event to another entity.

Mind you, this is usually done for incidents, not accidents. However, sometimes an accident is clearly due to illegal operation, and sometimes that means that a) matter is passed directly to prosecution b) investigation is closed without conclusion due to explicit disregard of safety mechanisms, thus making further investigation useless to the purpose of aircraft accident investigation (under common rules from ICAO that NTSB also operates when it comes to aircraft)

I wonder how they define a "civil aviation accident"? In places like Alaska, people routinely land at sites which are not airports. If someone has a hard landing, there could be some damage to the aircraft with no injuries. Do they investigate every one of those? It might be there are a lot of minor "accidents" that fall into grey areas. I don't know if that's the case, I'm actually curious if anyone knows.

"§ 830.2

Aircraft accident means an occurrence associated with the operation of an aircraft which takes place between the time any person boards the aircraft with the intention of flight and all such persons have disembarked, and in which any person suffers death or serious injury, or in which the aircraft receives substantial damage. "

https://www.law.cornell.edu/cfr/text/49/830.2

Later on the same page you can see how they define "substantial damage" and "civil aircraft" too.

That sounds like an incident, not an accident. They are treated differently.

> [1] Aircraft accident means an occurrence associated with the operation of an aircraft which takes place between the time any person boards the aircraft with the intention of flight and all such persons have disembarked, and in which any person suffers death or serious injury, or in which the aircraft receives substantial damage.

Substantial damage is then defined as:

> Substantial damage means damage or failure which adversely affects the structural strength, performance, or flight characteristics of the aircraft, and which would normally require major repair or replacement of the affected component. Engine failure or damage limited to an engine if only one engine fails or is damaged, bent fairings or cowling, dented skin, small punctured holes in the skin or fabric, ground damage to rotor or propeller blades, and damage to landing gear, wheels, tires, flaps, engine accessories, brakes, or wingtips are not considered substantial damage for the purpose of this part.

[1] https://www.law.cornell.edu/cfr/text/49/830.2

Accident, Incident and Serious Incident have explicit definitions in civil aviation, and are also graded internally and thus might have different scope of investigation.

A planned landing in terrain, if it caused no injuries but caused enough damage to aircraft to prevent takeoff without repair, would be classified as accident, but its investigation might be very brief depending on the event in question.

Essentially if you have an "occurence", you're required to report it to NTSB, which in turn will grade it and decide if you need even a cursory interview.

Not quite correct. You have to report any accident and any of a specific list of serious incidents to the NTSB. You do not have to report other incidents or occurrences.

https://www.law.cornell.edu/cfr/text/49/830.5

Also note: a landing that required repairs would not necessarily be an accident either, assuming no serious injuries occurred. "Engine failure or damage limited to an engine if only one engine fails or is damaged, bent fairings or cowling, dented skin, small punctured holes in the skin or fabric, ground damage to rotor or propeller blades, and damage to landing gear, wheels, tires, flaps, engine accessories, brakes, or wingtips are not considered “substantial damage” for the purpose of this part." (Those minor damages, even if they made the airplane require repairs prior to further flight, are not enough to make that landing an accident.)

Well, I'm going off more ICAO rules than NTSB specific - what I know for sure is that the differences you just specified are prerogative of NTSB and its parent govt to hash out (and seen it being decided upon in Polish PKBWL)