Unlikely that the QAR (or ONS server) would survive a high speed impact and subsequent extended immersion in salt water
True, but the data storage media would probably survive and the data be recoverable.
Or maybe not - there are a lot of variables.
I have known several business cases where data has been recovered from both flooded and fire damaged systems by specialist data recovery companies, they are very good at their job. If a fire gets into the server room the machines are usually wrecked and then drowned by the fire brigade but data is usually recoverable. Indeed, the opposite case of securely destroying sensitive data is very difficult and expensive.