Any life safety system should definitely not be designed to rely on GPS/Galileo/Glonass - they are RF systems that can be jammed by anyone with any interest in doing so.
I certainly wouldn't want to trust my life to the integrity of a -130 dBm strength signal. Particularly if I'm traveling in a tunnel, or heck, deep forest.
I think, though, that if the alternative is to trust my instincts (which I don't have), then I'd rather trust that -130 dBm strength signal. I think that my instincts are the secondary factor when I get lost in the forest, not the first factor. If I have no reason to think the GPS system is deceiving me, I would trust it.
For critical functions - combination of inertial navigation systems, mapping, radar, and plain old visual recognition of the location - after all, you need to have a sophisticated visual recognition system anyways to scan for all of the dynamic activity, why not extend it to be more broadly used? GPS is okay for gross navigation and tracking, just don't design any critical life-safety system to rely on it. I'd be very surprised if there were any boats/cars/planes that absolutely required GPS to be functioning for safe operation beyond the higher level navigation functions. Very disappointed as well.
