[quote The CVR was not available for the investigation.
No reason is given why, something I'm curious about. ]
Some pilots unions do not permit the regulator in that State to download a CVR if there were no fatalities. While the union is there to protect the interests of the crew by fair means or foul, any flight safety lessons learned from the incident are lost to other pilots.
In this case I believe we are not talking about unavailibity to a regulator, but instead an investigating agency. I doubt very much that the investigation can be prevented by anybody except a court citing a higher law.
Typically unavailability refers to a CVR that was overwritten by continuing to leave the power on in continued operation. This often happens where the incident is not necessarily immediately reportable to the investigatng authorities albeit might be reported to the regulator. It's a fine line and usually not an offence although there might be some hard feelings
