One troubling aspect of this is that it appears Alaska had reason to believe something was wrong with this plane but basically ignored it. They were getting pressurization warnings on prior flights, but the only action they took was restricting the plane from flying ETOPS routes.
They're the dominant carrier in my area, so these sorts of screwups make me nervous. I can't easily avoid using them without a fair amount of inconvenience.
Do you have a source for that? I'm not denying it, just curious to read more.
Logs are always generated, and logs include some amount of data about the user, if only environmental.
It's quite plausible that the spellchecker does not store your actual user data, but information about the request, or error logging includes more UGC than intended.
Note: I don't have any insider knowledge about their spellcheck API, but I've worked on similar systems which have similar language for little more than basic request logging.