During those first few seconds after I hit the Autoland button, the system went through a series of complex calculations and decision-making processes to determine the nearest suitable runway based on runway length, width, and surface; fuel remaining; crosswind component; terrain; obstacles; and general weather information. The system requires an RNAV approach, but beyond that, the runway and weather criteria can be decided by the airframe manufacturer.
The system even forecasts its own weather if the nearest suitable runway is a significant distance away, long enough that the current ADS-B or SiriusXM weather may not be valid. It uses the latest weather trend information, for example, to determine if a thunderstorm might move into the runway environment where it intends to land. It will route the airplane around thunderstorms as well as terrain and obstacles, all of which it gets from its internal databases. If en route to a runway it determines, because of changing weather conditions, that another runway is closer or more suitable, it will change its destination. It can even estimate changing barometric conditions and adjust the altimeter—using algorithms. Garmin engineers say the calculated barometric readings are within 0.01 inches of mercury of actual ambient conditions.
I try to make my landings a little less eventful.
Until GPS guidance came into use they were relatively crude terrain followers requiring a preloaded flight plan over a known terrain profile with sufficient bumpiness to protect against IMU drift. Nothing at all like this technology.
Yeah but an average human couldn't, and thankfully still cannot buy one. This is feature on a (and more to come) civilian aircraft, two very different things.
Even then, it's problematic: https://en.wikipedia.org/wiki/Iran%E2%80%93U.S._RQ-170_incid...
Because it's an emergency feature engaged by a passenger or automatically, it probably can't manage all complex situations. It may be just good weather emergency landing. Check fuel and wind, steer to nearest emergency airport and land. Best effort is better than no effort and dying.
> There is a mountain between the normal 3-degree glide-slope and the runway, an "offset approach"
I think it can land only to those airports that are it's database with landing approaches programmed it.
Cruise missiles have had similar technology for a long time.