>But that does not indicate anything about conditions where autopilot should not be used in which it is gravely dangerous.

Yes it does include those conditions because this specific accident occurred in conditions in which autopilot should not be used. That single fatality is the only one that autopilot has seen in close to one billion miles. That is an order of magnitude better than traditional fatality rates.

That leaves two possible scenarios. Either people are likely to use this system incorrectly, in which case many of those billion miles were used in poor conditions for the autopilot. Or few people are likely to use the system incorrectly, in which there is little to worry about since the autopilot system has never been involved in a reported fatality when used properly.